From 1e92e3491856005b10fa25764518a7086b8643b6 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Michael=20F=C3=A4rber?= <01mf02@gmail.com> Date: Mon, 30 Sep 2024 17:30:11 +0200 Subject: [PATCH 01/65] Generate docs from Markdown with Pandoc. --- .github/workflows/manpage.yml | 15 +- .github/workflows/website.yml | 4 + Makefile.am | 20 +- docs/README.md | 6 +- docs/build_manpage.py | 251 - docs/build_manpage.sh | 2 + docs/build_mantests.py | 21 - docs/build_mantests.sh | 7 + docs/build_manual.sh | 8 + docs/build_website.py | 4 + docs/content/manual/manual.md | 4539 +++++++++++++++++ docs/content/manual/manual.yml | 1 - docs/filters/filter.lua | 89 + docs/filters/tests.lua | 8 + docs/filters/toc.lua | 8 + docs/man/epilogue.md | 9 + docs/man/prologue.md | 30 + docs/manual_schema.yml | 60 - docs/templates/manual.html.j2 | 10 + docs/validate_manual_schema.py | 19 - jq.1.prebuilt | 8369 ++++++++++++++++---------------- tests/man.test | 1 + tests/manonig.test | 2 +- 23 files changed, 8934 insertions(+), 4549 deletions(-) delete mode 100755 docs/build_manpage.py create mode 100755 docs/build_manpage.sh delete mode 100755 docs/build_mantests.py create mode 100755 docs/build_mantests.sh create mode 100755 docs/build_manual.sh create mode 100644 docs/content/manual/manual.md delete mode 120000 docs/content/manual/manual.yml create mode 100644 docs/filters/filter.lua create mode 100644 docs/filters/tests.lua create mode 100644 docs/filters/toc.lua create mode 100644 docs/man/epilogue.md create mode 100644 docs/man/prologue.md delete mode 100644 docs/manual_schema.yml delete mode 100755 docs/validate_manual_schema.py diff --git a/.github/workflows/manpage.yml b/.github/workflows/manpage.yml index 72f1057709..f9634642ca 100644 --- a/.github/workflows/manpage.yml +++ b/.github/workflows/manpage.yml @@ -21,19 +21,10 @@ jobs: steps: - name: Checkout code uses: actions/checkout@v4 - - name: Setup Python - uses: actions/setup-python@v5 + - name: Install Pandoc + uses: pandoc/actions/setup@{main} with: - python-version: '3.11' - cache: pipenv - - name: Install pipenv - run: pip install pipenv - - name: Install dependencies - run: pipenv sync - working-directory: docs - - name: Validate manual schema - run: pipenv run python3 validate_manual_schema.py content/manual/**/*.yml - working-directory: docs + version: 3.4 - name: Configure run: | autoreconf -i diff --git a/.github/workflows/website.yml b/.github/workflows/website.yml index b69ea43e9c..e58bb19c03 100644 --- a/.github/workflows/website.yml +++ b/.github/workflows/website.yml @@ -17,6 +17,10 @@ jobs: uses: actions/checkout@v4 with: fetch-depth: 0 + - name: Install Pandoc + uses: pandoc/actions/setup@{main} + with: + version: 3.4 - name: Setup Python uses: actions/setup-python@v5 with: diff --git a/Makefile.am b/Makefile.am index a183477fde..24cb30d99f 100644 --- a/Makefile.am +++ b/Makefile.am @@ -160,11 +160,9 @@ check_DATA = tests/man.test # Making changes to the manpage without having the python deps means your # tests won't run. If you aren't making changes to the examples, you probably # don't care. But if you are, then you need to run the tests anyway. -tests/man.test tests/manonig.test: $(srcdir)/docs/content/manual/dev/manual.yml +tests/man.test tests/manonig.test: $(srcdir)/docs/content/manual/manual.md if ENABLE_DOCS - $(AM_V_GEN) ( cd ${abs_srcdir}/docs && \ - $(PIPENV) run python validate_manual_schema.py content/manual/dev/manual.yml && \ - $(PIPENV) run python build_mantests.py ) + $(AM_V_GEN) ( cd ${abs_srcdir}/docs && ./build_mantests.sh ) else @echo Changes to the manual.yml require docs to be enabled to update the manual test. @echo As a result, the manual test is out of date. @@ -176,11 +174,9 @@ endif # manpage, then we'll end up using the cached version. Otherwise, we need to # rebuild it. man_MANS = jq.1 -jq.1.prebuilt: $(srcdir)/docs/content/manual/dev/manual.yml +jq.1.prebuilt: $(srcdir)/docs/content/manual/manual.md if ENABLE_DOCS - $(AM_V_GEN) ( cd ${abs_srcdir}/docs && \ - $(PIPENV) run python validate_manual_schema.py content/manual/dev/manual.yml && \ - $(PIPENV) run python build_manpage.py ) > $@ + $(AM_V_GEN) ( cd ${abs_srcdir}/docs && ./build_manpage.sh ) > $@ else @echo Changes to the manual.yml require docs to be enabled to update the manpage. @echo As a result, the manpage is out of date. @@ -209,10 +205,10 @@ endif install-binaries: $(BUILT_SOURCES) $(MAKE) $(AM_MAKEFLAGS) install-exec -DOC_FILES = docs/content docs/public docs/templates \ - docs/Pipfile docs/Pipfile.lock docs/build_manpage.py \ - docs/build_mantests.py docs/build_website.py docs/README.md \ - docs/validate_manual_schema.py docs/manual_schema.yml +DOC_FILES = docs/content docs/public docs/templates docs/filters \ + docs/man docs/Pipfile docs/Pipfile.lock docs/build_manpage.sh \ + docs/build_mantests.sh docs/build_website.py docs/README.md \ + docs/build_manual.sh EXTRA_DIST = $(DOC_FILES) $(man_MANS) $(TESTS) $(TEST_LOG_COMPILER) \ jq.1.prebuilt jq.spec src/lexer.c src/lexer.h src/parser.c \ diff --git a/docs/README.md b/docs/README.md index 9fce6c63df..9c7ed41f8f 100644 --- a/docs/README.md +++ b/docs/README.md @@ -2,9 +2,11 @@ Documentation ============= The jq website, manpages and some of the tests are generated from this -directory. The manual is a YAML file in `content/manual`. +directory. The manual is a Markdown file in `content/manual/manual.md`. -To build the documentation (including building the jq manpage), you'll +To build the jq manpage and the tests contained in it, you'll +need `pandoc` (at least version 3.0). +To build the website, you'll additionally need `python3` and `pipenv`. You can install `pipenv` like so: pip install pipenv diff --git a/docs/build_manpage.py b/docs/build_manpage.py deleted file mode 100755 index da916cc5c3..0000000000 --- a/docs/build_manpage.py +++ /dev/null @@ -1,251 +0,0 @@ -#!/usr/bin/env python3 -from datetime import date -from io import StringIO -from lxml import etree -import markdown -from markdown.extensions import Extension -import re -import sys -import yaml - - -# Prevent our markdown parser from trying to help by interpreting things in angle brackets as HTML tags. -class EscapeHtml(Extension): - - def extendMarkdown(self, md): - md.preprocessors.deregister('html_block') - md.inlinePatterns.deregister('html') - - -class RoffWalker(object): - - def __init__(self, tree, output=sys.stdout): - self.tree = tree - self.target = output - self.f = StringIO() - - def walk(self): - self._walk(self.tree, parent_tag=None) - # We don't want to start lines with \. because that can confuse man - # For lines that start with \., we need to prefix them with \& so it - # knows not to treat that line as a directive - data = re.sub(r'^\\\.', r'\&.', self.f.getvalue(), flags=re.MULTILINE) - self.target.write(data) - - def _ul_is_special(self, root): - if len(root) != 1: - return False - child = root[0] - if child.tag != 'li': - return False - msg = ''.join(child.itertext()).strip() - return msg.endswith(':') - - def _walk_child(self, root): - if len(root) > 0: - self._walk(root[0], parent_tag=root.tag) - - def _write_element(self, root, ensure_newline=True): - if root.text is not None: - text = self._sanitize(root.text) - self.__write_raw(text) - self._walk_child(root) - self._write_tail(root, ensure_newline=ensure_newline) - - def _write_tail(self, root, ensure_newline=False, inline=False): - if root.tail is not None: - if inline or root.tail != '\n': - text = self._sanitize(root.tail) - if text.endswith('\n'): - ensure_newline = False - self.__write_raw(text) - if ensure_newline: - self.__write_raw('\n') - - def _walk(self, root, parent_tag=None): - last_tag = None - while root is not None: - if root.tag == 'h1': - self.__write_cmd('.TH "JQ" "1" "{}" "" ""'.format( - date.today().strftime('%B %Y'))) - self.__write_cmd('.SH "NAME"') - # TODO: properly parse this - self.__write_raw(r'\fBjq\fR \- Command\-line JSON processor' + - "\n") - - elif root.tag == 'h2': - self.__write_cmd('.SH "{}"'.format(''.join( - root.itertext()).strip())) - - elif root.tag == 'h3': - text = ''.join(root.itertext()).strip() - self.__write_cmd('.SS "{}"'.format(self._h3_sanitize(text))) - - elif root.tag == 'p': - if last_tag not in ['h2', 'h3'] and parent_tag not in ['li']: - self.__write_cmd('.P') - self._write_element(root, ensure_newline=(parent_tag != 'li')) - - elif root.tag == 'a': - self._write_element(root, ensure_newline=(parent_tag != 'li')) - - elif root.tag == 'ul': - if self._ul_is_special(root): - li = root[0] - self.__write_cmd('.TP') - self._write_element(li) - next = root.getnext() - while next is not None and next.tag == 'p': - if next.getnext() is not None and next.getnext( - ).tag == 'pre': - # we don't want to .IP these, because it'll look funny with the code indent - break - self.__write_cmd('.IP') - self._write_element(next) - root = next - next = root.getnext() - else: - self._walk_child(root) - self._write_tail(root) - # A pre tag after the end of a list doesn't want two of the indentation commands - if root.getnext() is None or root.getnext().tag != 'pre': - self.__write_cmd('.IP "" 0') - - elif root.tag == 'li': - self.__write_cmd(r'.IP "\(bu" 4') - if root.text is not None and root.text.strip() != '': - text = self._sanitize(root.text) - self.__write_raw(text) - self._walk_child(root) - self._write_tail(root, ensure_newline=True) - - elif root.tag == 'strong': - if root.text is not None: - text = self._sanitize(root.text) - self.__write_raw('\\fB{}\\fR'.format(text)) - - self._write_tail(root, inline=True) - - elif root.tag == 'em': - if root.text is not None: - text = self._sanitize(root.text) - self.__write_raw('\\fI{}\\fR'.format(text)) - self._write_tail(root, inline=True) - - elif root.tag == 'code': - if root.text is not None: - text = self._code_sanitize(root.text) - self.__write_raw('\\fB{}\\fR'.format(text)) - self._write_tail(root, inline=True) - - elif root.tag == 'pre': - self.__write_cmd('.IP "" 4') - self.__write_cmd('.nf\n') # extra newline for spacing reasons - next = root - first = True - while next is not None and next.tag == 'pre': - if not first: - self.__write_raw('\n') - text = ''.join(next.itertext(with_tail=False)) - self.__write_raw(self._pre_sanitize(text)) - first = False - root = next - next = next.getnext() - self.__write_cmd('.fi') - self.__write_cmd('.IP "" 0') - - else: - self._walk_child(root) - - last_tag = root.tag - root = root.getnext() - - def _base_sanitize(self, text): - text = re.sub(r'\\', r'\\e', text) - text = re.sub(r'\.', r'\\.', text) - text = re.sub("'", r"\'", text) - text = re.sub('-', r'\-', text) - return text - - def _pre_sanitize(self, text): - return self._base_sanitize(text) - - def _code_sanitize(self, text): - text = self._base_sanitize(text) - text = re.sub(r'\s', ' ', text) - return text - - def _h3_sanitize(self, text): - text = self._base_sanitize(text) - text = re.sub(' \n|\n ', ' ', text) - text = re.sub('\n', ' ', text) - return text - - def _sanitize(self, text): - text = self._base_sanitize(text) - text = re.sub(r'<([^>]+)>', r'\\fI\1\\fR', text) - text = re.sub(r' +', ' ', text) - text = re.sub('\n', ' ', text) - return text - - def __write_cmd(self, dat): - print('.', dat, sep='\n', file=self.f) - pass - - def __write_raw(self, dat): - print(dat, sep='', end='', file=self.f) - pass - - -def load_yml_file(fn): - with open(fn) as f: - return yaml.safe_load(f) - - -def dedent_body(body): - lines = [re.sub(r'^ (\S)', r'\1', l) for l in body.split('\n')] - return '\n'.join(lines) - - -def convert_manual_to_markdown(): - f = StringIO() - manual = load_yml_file("content/manual/dev/manual.yml") - f.write(manual.get('manpage_intro', '\n')) - f.write(dedent_body(manual.get('body', '\n'))) - for section in manual.get('sections', []): - f.write('## {}\n'.format(section.get('title', '').upper())) - f.write(dedent_body(section.get('body', '\n'))) - f.write('\n') - for entry in section.get('entries', []): - f.write('### {}\n'.format(entry.get('title', ''))) - f.write(dedent_body(entry.get('body', '\n'))) - f.write('\n') - if entry.get('examples') is not None: - f.write("~~~~\n") - first = True - for example in entry.get('examples'): - if not first: - f.write('\n') - f.write("jq '{}'\n".format(example.get('program', ''))) - f.write(" {}\n".format(example.get('input', ''))) - output = [str(x) for x in example.get('output', [])] - f.write("=> {}\n".format(', '.join(output))) - first = False - f.write("~~~~\n") - f.write('\n') - f.write(manual.get('manpage_epilogue', '')) - return f.getvalue() - - -# Convert manual.yml to our special markdown format -markdown_data = convert_manual_to_markdown() - -# Convert markdown to html -html_data = markdown.markdown(markdown_data, - extensions=[EscapeHtml(), 'fenced_code']) - -# Parse the html into a tree so we can walk it -tr = etree.HTML(html_data, etree.HTMLParser()) - -# Convert the markdown to ROFF -RoffWalker(tr).walk() diff --git a/docs/build_manpage.sh b/docs/build_manpage.sh new file mode 100755 index 0000000000..ceee525e4a --- /dev/null +++ b/docs/build_manpage.sh @@ -0,0 +1,2 @@ +#!/bin/sh +pandoc man/prologue.md content/manual/manual.md man/epilogue.md -s --to=man --lua-filter filters/filter.lua diff --git a/docs/build_mantests.py b/docs/build_mantests.py deleted file mode 100755 index bbc7e325bb..0000000000 --- a/docs/build_mantests.py +++ /dev/null @@ -1,21 +0,0 @@ -#!/usr/bin/env python3 -import yaml -import re - -regex_program_pattern = re.compile( - r'\b(?:test|match|capture|scan|split|splits|sub|gsub)\s*\(') - -with open('content/manual/dev/manual.yml') as source, \ - open('../tests/man.test', 'w') as man, \ - open('../tests/manonig.test', 'w') as manonig: - manual = yaml.safe_load(source) - for section in manual.get('sections', []): - for entry in section.get('entries', []): - for example in entry.get('examples', []): - program = example.get('program', '').replace('\n', ' ') - out = manonig if regex_program_pattern.search(program) else man - print(program, file=out) - print(example.get('input', ''), file=out) - for s in example.get('output', []): - print(s, file=out) - print('', file=out) diff --git a/docs/build_mantests.sh b/docs/build_mantests.sh new file mode 100755 index 0000000000..75f048af9a --- /dev/null +++ b/docs/build_mantests.sh @@ -0,0 +1,7 @@ +#!/bin/sh +mkdir -p tests +pandoc content/manual/manual.md --lua-filter filters/tests.lua | split --separator='\0' -l1 - tests/ +REGEX="test|match|capture|scan|split|splits|sub|gsub" +grep -L -E $REGEX tests/* | xargs cat | sed 's/\x0/\n/g' > ../tests/man.test +grep -l -E $REGEX tests/* | xargs cat | sed 's/\x0/\n/g' > ../tests/manonig.test +rm -r tests diff --git a/docs/build_manual.sh b/docs/build_manual.sh new file mode 100755 index 0000000000..b31866a4e8 --- /dev/null +++ b/docs/build_manual.sh @@ -0,0 +1,8 @@ +#!/bin/bash +echo "headline: jq Manual" +echo "body: |" +pandoc content/manual/manual.md --lua-filter filters/filter.lua \ + --shift-heading-level-by=1 --section-divs | \ + sed 's/\(.*\)/ \1/g' +echo "toc:" +pandoc content/manual/manual.md --lua-filter filters/toc.lua diff --git a/docs/build_website.py b/docs/build_website.py index 2b3afc77e2..b24eb0534b 100755 --- a/docs/build_website.py +++ b/docs/build_website.py @@ -91,5 +91,9 @@ def copy_public_files(root=''): os.makedirs('output', exist_ok=True) copy_public_files() +os.system("./build_manual.sh > content/manual/manual.yml") + for fn in glob.glob('content/**/*.yml', recursive=True): generate_file(env, fn) + +os.remove("content/manual/manual.yml") diff --git a/docs/content/manual/manual.md b/docs/content/manual/manual.md new file mode 100644 index 0000000000..b1568c70c8 --- /dev/null +++ b/docs/content/manual/manual.md @@ -0,0 +1,4539 @@ + +A jq program is a "filter": it takes an input, and produces an +output. There are a lot of builtin filters for extracting a +particular field of an object, or converting a number to a string, +or various other standard tasks. + +Filters can be combined in various ways - you can pipe the output of +one filter into another filter, or collect the output of a filter +into an array. + +Some filters produce multiple results, for instance there's one that +produces all the elements of its input array. Piping that filter +into a second runs the second filter for each element of the +array. Generally, things that would be done with loops and iteration +in other languages are just done by gluing filters together in jq. + +It's important to remember that every filter has an input and an +output. Even literals like "hello" or 42 are filters - they take an +input but always produce the same literal as output. Operations that +combine two filters, like addition, generally feed the same input to +both and combine the results. So, you can implement an averaging +filter as `add / length` - feeding the input array both to the `add` +filter and the `length` filter and then performing the division. + +But that's getting ahead of ourselves. :) Let's start with something +simpler: + +# Invoking jq + +jq filters run on a stream of JSON data. The input to jq is +parsed as a sequence of whitespace-separated JSON values which +are passed through the provided filter one at a time. The +output(s) of the filter are written to standard output, as a +sequence of newline-separated JSON data. + +The simplest and most common filter (or jq program) is `.`, +which is the identity operator, copying the inputs of the jq +processor to the output stream. Because the default behavior of +the jq processor is to read JSON texts from the input stream, +and to pretty-print outputs, the `.` program's main use is to +validate and pretty-print the inputs. The jq programming +language is quite rich and allows for much more than just +validation and pretty-printing. + +Note: it is important to mind the shell's quoting rules. As a +general rule it's best to always quote (with single-quote +characters on Unix shells) the jq program, as too many characters with special +meaning to jq are also shell meta-characters. For example, `jq +"foo"` will fail on most Unix shells because that will be the same +as `jq foo`, which will generally fail because `foo is not +defined`. When using the Windows command shell (cmd.exe) it's +best to use double quotes around your jq program when given on the +command-line (instead of the `-f program-file` option), but then +double-quotes in the jq program need backslash escaping. When using +the Powershell (`powershell.exe`) or the Powershell Core +(`pwsh`/`pwsh.exe`), use single-quote characters around the jq +program and backslash-escaped double-quotes (`\"`) inside the jq +program. + +* Unix shells: `jq '.["foo"]'` +* Powershell: `jq '.[\"foo\"]'` +* Windows command shell: `jq ".[\"foo\"]"` + +Note: jq allows user-defined functions, but every jq program +must have a top-level expression. + +You can affect how jq reads and writes its input and output +using some command-line options: + +* `--null-input` / `-n`: + + Don't read any input at all. Instead, the filter is run once + using `null` as the input. This is useful when using jq as a + simple calculator or to construct JSON data from scratch. + +* `--raw-input` / `-R`: + + Don't parse the input as JSON. Instead, each line of text is + passed to the filter as a string. If combined with `--slurp`, + then the entire input is passed to the filter as a single long + string. + +* `--slurp` / `-s`: + + Instead of running the filter for each JSON object in the + input, read the entire input stream into a large array and run + the filter just once. + +* `--compact-output` / `-c`: + + By default, jq pretty-prints JSON output. Using this option + will result in more compact output by instead putting each + JSON object on a single line. + +* `--raw-output` / `-r`: + + With this option, if the filter's result is a string then it + will be written directly to standard output rather than being + formatted as a JSON string with quotes. This can be useful for + making jq filters talk to non-JSON-based systems. + +* `--raw-output0`: + + Like `-r` but jq will print NUL instead of newline after each output. + This can be useful when the values being output can contain newlines. + When the output value contains NUL, jq exits with non-zero code. + +* `--join-output` / `-j`: + + Like `-r` but jq won't print a newline after each output. + +* `--ascii-output` / `-a`: + + jq usually outputs non-ASCII Unicode codepoints as UTF-8, even + if the input specified them as escape sequences (like + "\u03bc"). Using this option, you can force jq to produce pure + ASCII output with every non-ASCII character replaced with the + equivalent escape sequence. + +* `--sort-keys` / `-S`: + + Output the fields of each object with the keys in sorted order. + +* `--color-output` / `-C` and `--monochrome-output` / `-M`: + + By default, jq outputs colored JSON if writing to a + terminal. You can force it to produce color even if writing to + a pipe or a file using `-C`, and disable color with `-M`. + When the `NO_COLOR` environment variable is not empty, jq disables + colored output by default, but you can enable it by `-C`. + + Colors can be configured with the `JQ_COLORS` environment + variable (see below). + +* `--tab`: + + Use a tab for each indentation level instead of two spaces. + +* `--indent n`: + + Use the given number of spaces (no more than 7) for indentation. + +* `--unbuffered`: + + Flush the output after each JSON object is printed (useful if + you're piping a slow data source into jq and piping jq's + output elsewhere). + +* `--stream`: + + Parse the input in streaming fashion, outputting arrays of path + and leaf values (scalars and empty arrays or empty objects). + For example, `"a"` becomes `[[],"a"]`, and `[[],"a",["b"]]` + becomes `[[0],[]]`, `[[1],"a"]`, and `[[2,0],"b"]`. + + This is useful for processing very large inputs. Use this in + conjunction with filtering and the `reduce` and `foreach` syntax + to reduce large inputs incrementally. + +* `--stream-errors`: + + Like `--stream`, but invalid JSON inputs yield array values + where the first element is the error and the second is a path. + For example, `["a",n]` produces `["Invalid literal at line 1, + column 7",[1]]`. + + Implies `--stream`. Invalid JSON inputs produce no error values + when `--stream` without `--stream-errors`. + +* `--seq`: + + Use the `application/json-seq` MIME type scheme for separating + JSON texts in jq's input and output. This means that an ASCII + RS (record separator) character is printed before each value on + output and an ASCII LF (line feed) is printed after every + output. Input JSON texts that fail to parse are ignored (but + warned about), discarding all subsequent input until the next + RS. This mode also parses the output of jq without the `--seq` + option. + +* `-f filename` / `--from-file filename`: + + Read filter from the file rather than from a command line, like + awk's -f option. + +* `-L directory`: + + Prepend `directory` to the search list for modules. If this + option is used then no builtin search list is used. See the + section on modules below. + +* `--arg name value`: + + This option passes a value to the jq program as a predefined + variable. If you run jq with `--arg foo bar`, then `$foo` is + available in the program and has the value `"bar"`. Note that + `value` will be treated as a string, so `--arg foo 123` will + bind `$foo` to `"123"`. + + Named arguments are also available to the jq program as + `$ARGS.named`. + +* `--argjson name JSON-text`: + + This option passes a JSON-encoded value to the jq program as a + predefined variable. If you run jq with `--argjson foo 123`, then + `$foo` is available in the program and has the value `123`. + +* `--slurpfile variable-name filename`: + + This option reads all the JSON texts in the named file and binds + an array of the parsed JSON values to the given global variable. + If you run jq with `--slurpfile foo bar`, then `$foo` is available + in the program and has an array whose elements correspond to the + texts in the file named `bar`. + +* `--rawfile variable-name filename`: + + This option reads in the named file and binds its contents to the given + global variable. If you run jq with `--rawfile foo bar`, then `$foo` is + available in the program and has a string whose contents are to the texts + in the file named `bar`. + +* `--args`: + + Remaining arguments are positional string arguments. These are + available to the jq program as `$ARGS.positional[]`. + +* `--jsonargs`: + + Remaining arguments are positional JSON text arguments. These + are available to the jq program as `$ARGS.positional[]`. + +* `--exit-status` / `-e`: + + Sets the exit status of jq to 0 if the last output value was + neither `false` nor `null`, 1 if the last output value was + either `false` or `null`, or 4 if no valid result was ever + produced. Normally jq exits with 2 if there was any usage + problem or system error, 3 if there was a jq program compile + error, or 0 if the jq program ran. + + Another way to set the exit status is with the `halt_error` + builtin function. + +* `--binary` / `-b`: + + Windows users using WSL, MSYS2, or Cygwin, should use this option + when using a native jq.exe, otherwise jq will turn newlines (LFs) + into carriage-return-then-newline (CRLF). + +* `--version` / `-V`: + + Output the jq version and exit with zero. + +* `--build-configuration`: + + Output the build configuration of jq and exit with zero. + This output has no supported format or structure and may change + without notice in future releases. + +* `--help` / `-h`: + + Output the jq help and exit with zero. + +* `--`: + + Terminates argument processing. Remaining arguments are not + interpreted as options. + +* `--run-tests [filename]`: + + Runs the tests in the given file or standard input. This must + be the last option given and does not honor all preceding + options. The input consists of comment lines, empty lines, and + program lines followed by one input line, as many lines of + output as are expected (one per output), and a terminating empty + line. Compilation failure tests start with a line containing + only `%%FAIL`, then a line containing the program to compile, + then a line containing an error message to compare to the + actual. + + Be warned that this option can change backwards-incompatibly. + +# Basic filters + +## Identity: `.` + +The absolute simplest filter is `.` . This filter takes its +input and produces the same value as output. That is, this +is the identity operator. + +Since jq by default pretty-prints all output, a trivial +program consisting of nothing but `.` can be used to format +JSON output from, say, `curl`. + +Although the identity filter never modifies the value of its +input, jq processing can sometimes make it appear as though +it does. For example, using the current implementation of +jq, we would see that the expression: + + 1E1234567890 | . + +produces `1.7976931348623157e+308` on at least one platform. +This is because, in the process of parsing the number, this +particular version of jq has converted it to an IEEE754 +double-precision representation, losing precision. + +The way in which jq handles numbers has changed over time +and further changes are likely within the parameters set by +the relevant JSON standards. Moreover, build configuration +options can alter how jq processes numbers. + +The following remarks are therefore offered with the +understanding that they are intended to be descriptive of the +current version of jq and should not be interpreted as being +prescriptive: + +(1) Any arithmetic operation on a number that has not +already been converted to an IEEE754 double precision +representation will trigger a conversion to the IEEE754 +representation. + +(2) jq will attempt to maintain the original decimal +precision of number literals (if the `--disable-decnum` +build configuration option was not used), but in expressions +such `1E1234567890`, precision will be lost if the exponent +is too large. + +(3) In jq programs, a leading minus sign will trigger the +conversion of the number to an IEEE754 representation. + +(4) Comparisons are carried out using the untruncated +big decimal representation of numbers if available, as +illustrated in one of the following examples. + +The examples below use the builtin function `have_decnum` in +order to demonstrate the expected effects of using / not +using the `--disable-decnum` build configuration option, and +also to allow automated tests derived from these examples to +pass regardless of whether that option is used. + +::: Examples + +~~~ +. +"Hello, world!" +"Hello, world!" +~~~ + +~~~ +. +0.12345678901234567890123456789 +0.12345678901234567890123456789 +~~~ + +~~~ +[., tojson] | . == if have_decnum then [12345678909876543212345,"12345678909876543212345"] else [12345678909876543000000,"12345678909876543000000"] end +12345678909876543212345 +true +~~~ + +~~~ +. < 0.12345678901234567890123456788 +0.12345678901234567890123456789 +false +~~~ + +~~~ +map([., . == 1]) | tojson | . == if have_decnum then "[[1,true],[1.000,true],[1.0,true],[1.00,true]]" else "[[1,true],[1,true],[1,true],[1,true]]" end +[1, 1.000, 1.0, 100e-2] +true +~~~ + +~~~ +. as $big | [$big, $big + 1] | map(. > 10000000000000000000000000000000) | . == if have_decnum then [true, false] else [false, false] end +10000000000000000000000000000001 +true +~~~ + +::: + +## Object Identifier-Index: `.foo`, `.foo.bar` + +The simplest *useful* filter has the form `.foo`. When given a +JSON object (aka dictionary or hash) as input, `.foo` produces +the value at the key "foo" if the key is present, or null otherwise. + +A filter of the form `.foo.bar` is equivalent to `.foo | .bar`. + +The `.foo` syntax only works for simple, identifier-like keys, that +is, keys that are all made of alphanumeric characters and +underscore, and which do not start with a digit. + +If the key contains special characters or starts with a digit, +you need to surround it with double quotes like this: +`."foo$"`, or else `.["foo$"]`. + +For example `.["foo::bar"]` and `.["foo.bar"]` work while +`.foo::bar` does not. + +::: Examples + +~~~ +.foo +{"foo": 42, "bar": "less interesting data"} +42 +~~~ + +~~~ +.foo +{"notfoo": true, "alsonotfoo": false} +null +~~~ + +~~~ +.["foo"] +{"foo": 42} +42 +~~~ + +::: + +## Optional Object Identifier-Index: `.foo?` + +Just like `.foo`, but does not output an error when `.` is not an +object. + +::: Examples + +~~~ +.foo? +{"foo": 42, "bar": "less interesting data"} +42 +~~~ + +~~~ +.foo? +{"notfoo": true, "alsonotfoo": false} +null +~~~ + +~~~ +.["foo"]? +{"foo": 42} +42 +~~~ + +~~~ +[.foo?] +[1,2] +[] +~~~ + +::: + +## Object Index: `.[]` + +You can also look up fields of an object using syntax like +`.["foo"]` (`.foo` above is a shorthand version of this, but +only for identifier-like strings). + +## Array Index: `.[]` + +When the index value is an integer, `.[]` can index +arrays. Arrays are zero-based, so `.[2]` returns the third +element. + +Negative indices are allowed, with -1 referring to the last +element, -2 referring to the next to last element, and so on. + +::: Examples + +~~~ +.[0] +[{"name":"JSON", "good":true}, {"name":"XML", "good":false}] +{"name":"JSON", "good":true} +~~~ + +~~~ +.[2] +[{"name":"JSON", "good":true}, {"name":"XML", "good":false}] +null +~~~ + +~~~ +.[-2] +[1,2,3] +2 +~~~ + +::: + +## Array/String Slice: `.[:]` + +The `.[:]` syntax can be used to return a +subarray of an array or substring of a string. The array +returned by `.[10:15]` will be of length 5, containing the +elements from index 10 (inclusive) to index 15 (exclusive). +Either index may be negative (in which case it counts +backwards from the end of the array), or omitted (in which +case it refers to the start or end of the array). +Indices are zero-based. + +::: Examples + +~~~ +.[2:4] +["a","b","c","d","e"] +["c", "d"] +~~~ + +~~~ +.[2:4] +"abcdefghi" +"cd" +~~~ + +~~~ +.[:3] +["a","b","c","d","e"] +["a", "b", "c"] +~~~ + +~~~ +.[-2:] +["a","b","c","d","e"] +["d", "e"] +~~~ + +::: + +## Array/Object Value Iterator: `.[]` + +If you use the `.[index]` syntax, but omit the index +entirely, it will return *all* of the elements of an +array. Running `.[]` with the input `[1,2,3]` will produce the +numbers as three separate results, rather than as a single +array. A filter of the form `.foo[]` is equivalent to +`.foo | .[]`. + +You can also use this on an object, and it will return all +the values of the object. + +Note that the iterator operator is a generator of values. + +::: Examples + +~~~ +.[] +[{"name":"JSON", "good":true}, {"name":"XML", "good":false}] +{"name":"JSON", "good":true} +{"name":"XML", "good":false} +~~~ + +~~~ +.[] +[] + +~~~ + +~~~ +.foo[] +{"foo":[1,2,3]} +1 +2 +3 +~~~ + +~~~ +.[] +{"a": 1, "b": 1} +1 +1 +~~~ + +::: + +## `.[]?` + +Like `.[]`, but no errors will be output if . is not an array +or object. A filter of the form `.foo[]?` is equivalent to +`.foo | .[]?`. + +## Comma: `,` + +If two filters are separated by a comma, then the +same input will be fed into both and the two filters' output +value streams will be concatenated in order: first, all of the +outputs produced by the left expression, and then all of the +outputs produced by the right. For instance, filter `.foo, +.bar`, produces both the "foo" fields and "bar" fields as +separate outputs. + +The `,` operator is one way to construct generators. + +::: Examples + +~~~ +.foo, .bar +{"foo": 42, "bar": "something else", "baz": true} +42 +"something else" +~~~ + +~~~ +.user, .projects[] +{"user":"stedolan", "projects": ["jq", "wikiflow"]} +"stedolan" +"jq" +"wikiflow" +~~~ + +~~~ +.[4,2] +["a","b","c","d","e"] +"e" +"c" +~~~ + +::: + +## Pipe: `|` + +The | operator combines two filters by feeding the output(s) of +the one on the left into the input of the one on the right. It's +similar to the Unix shell's pipe, if you're used to that. + +If the one on the left produces multiple results, the one on +the right will be run for each of those results. So, the +expression `.[] | .foo` retrieves the "foo" field of each +element of the input array. This is a cartesian product, +which can be surprising. + +Note that `.a.b.c` is the same as `.a | .b | .c`. + +Note too that `.` is the input value at the particular stage +in a "pipeline", specifically: where the `.` expression appears. +Thus `.a | . | .b` is the same as `.a.b`, as the `.` in the +middle refers to whatever value `.a` produced. + +::: Examples + +~~~ +.[] | .name +[{"name":"JSON", "good":true}, {"name":"XML", "good":false}] +"JSON" +"XML" +~~~ + +::: + +## Parenthesis + +Parenthesis work as a grouping operator just as in any typical +programming language. + +::: Examples + +~~~ +(. + 2) * 5 +1 +15 +~~~ + +::: + +# Types and Values + +jq supports the same set of datatypes as JSON - numbers, +strings, booleans, arrays, objects (which in JSON-speak are +hashes with only string keys), and "null". + +Booleans, null, strings and numbers are written the same way as +in JSON. Just like everything else in jq, these simple +values take an input and produce an output - `42` is a valid jq +expression that takes an input, ignores it, and returns 42 +instead. + +Numbers in jq are internally represented by their IEEE754 double +precision approximation. Any arithmetic operation with numbers, +whether they are literals or results of previous filters, will +produce a double precision floating point result. + +However, when parsing a literal jq will store the original literal +string. If no mutation is applied to this value then it will make +to the output in its original form, even if conversion to double +would result in a loss. + +## Array construction: `[]` + +As in JSON, `[]` is used to construct arrays, as in +`[1,2,3]`. The elements of the arrays can be any jq +expression, including a pipeline. All of the results produced +by all of the expressions are collected into one big array. +You can use it to construct an array out of a known quantity +of values (as in `[.foo, .bar, .baz]`) or to "collect" all the +results of a filter into an array (as in `[.items[].name]`) + +Once you understand the "," operator, you can look at jq's array +syntax in a different light: the expression `[1,2,3]` is not using a +built-in syntax for comma-separated arrays, but is instead applying +the `[]` operator (collect results) to the expression 1,2,3 (which +produces three different results). + +If you have a filter `X` that produces four results, +then the expression `[X]` will produce a single result, an +array of four elements. + +::: Examples + +~~~ +[.user, .projects[]] +{"user":"stedolan", "projects": ["jq", "wikiflow"]} +["stedolan", "jq", "wikiflow"] +~~~ + +~~~ +[ .[] | . * 2] +[1, 2, 3] +[2, 4, 6] +~~~ + +::: + +## Object Construction: `{}` + +Like JSON, `{}` is for constructing objects (aka +dictionaries or hashes), as in: `{"a": 42, "b": 17}`. + +If the keys are "identifier-like", then the quotes can be left +off, as in `{a:42, b:17}`. Variable references as key +expressions use the value of the variable as the key. Key +expressions other than constant literals, identifiers, or +variable references, need to be parenthesized, e.g., +`{("a"+"b"):59}`. + +The value can be any expression (although you may need to wrap +it in parentheses if, for example, it contains colons), which +gets applied to the {} expression's input (remember, all +filters have an input and an output). + + {foo: .bar} + +will produce the JSON object `{"foo": 42}` if given the JSON +object `{"bar":42, "baz":43}` as its input. You can use this +to select particular fields of an object: if the input is an +object with "user", "title", "id", and "content" fields and +you just want "user" and "title", you can write + + {user: .user, title: .title} + +Because that is so common, there's a shortcut syntax for it: +`{user, title}`. + +If one of the expressions produces multiple results, +multiple dictionaries will be produced. If the input's + + {"user":"stedolan","titles":["JQ Primer", "More JQ"]} + +then the expression + + {user, title: .titles[]} + +will produce two outputs: + + {"user":"stedolan", "title": "JQ Primer"} + {"user":"stedolan", "title": "More JQ"} + +Putting parentheses around the key means it will be evaluated as an +expression. With the same input as above, + + {(.user): .titles} + +produces + + {"stedolan": ["JQ Primer", "More JQ"]} + +Variable references as keys use the value of the variable as +the key. Without a value then the variable's name becomes the +key and its value becomes the value, + + "f o o" as $foo | "b a r" as $bar | {$foo, $bar:$foo} + +produces + + {"foo":"f o o","b a r":"f o o"} + +::: Examples + +~~~ +{user, title: .titles[]} +{"user":"stedolan","titles":["JQ Primer", "More JQ"]} +{"user":"stedolan", "title": "JQ Primer"} +{"user":"stedolan", "title": "More JQ"} +~~~ + +~~~ +{(.user): .titles} +{"user":"stedolan","titles":["JQ Primer", "More JQ"]} +{"stedolan": ["JQ Primer", "More JQ"]} +~~~ + +::: + +## Recursive Descent: `..` + +Recursively descends `.`, producing every value. This is the +same as the zero-argument `recurse` builtin (see below). This +is intended to resemble the XPath `//` operator. Note that +`..a` does not work; use `.. | .a` instead. In the example +below we use `.. | .a?` to find all the values of object keys +"a" in any object found "below" `.`. + +This is particularly useful in conjunction with `path(EXP)` +(also see below) and the `?` operator. + +::: Examples + +~~~ +.. | .a? +[[{"a":1}]] +1 +~~~ + +::: + +# Builtin operators and functions + +Some jq operators (for instance, `+`) do different things +depending on the type of their arguments (arrays, numbers, +etc.). However, jq never does implicit type conversions. If you +try to add a string to an object you'll get an error message and +no result. + +Please note that all numbers are converted to IEEE754 double precision +floating point representation. Arithmetic and logical operators are working +with these converted doubles. Results of all such operations are also limited +to the double precision. + +The only exception to this behaviour of number is a snapshot of original number +literal. When a number which originally was provided as a literal is never +mutated until the end of the program then it is printed to the output in its +original literal form. This also includes cases when the original literal +would be truncated when converted to the IEEE754 double precision floating point +number. + +## Addition: `+` + +The operator `+` takes two filters, applies them both +to the same input, and adds the results together. What +"adding" means depends on the types involved: + +- **Numbers** are added by normal arithmetic. + +- **Arrays** are added by being concatenated into a larger array. + +- **Strings** are added by being joined into a larger string. + +- **Objects** are added by merging, that is, inserting all + the key-value pairs from both objects into a single + combined object. If both objects contain a value for the + same key, the object on the right of the `+` wins. (For + recursive merge use the `*` operator.) + +`null` can be added to any value, and returns the other +value unchanged. + +::: Examples + +~~~ +.a + 1 +{"a": 7} +8 +~~~ + +~~~ +.a + .b +{"a": [1,2], "b": [3,4]} +[1,2,3,4] +~~~ + +~~~ +.a + null +{"a": 1} +1 +~~~ + +~~~ +.a + 1 +{} +1 +~~~ + +~~~ +{a: 1} + {b: 2} + {c: 3} + {a: 42} +null +{"a": 42, "b": 2, "c": 3} +~~~ + +::: + +## Subtraction: `-` + +As well as normal arithmetic subtraction on numbers, the `-` +operator can be used on arrays to remove all occurrences of +the second array's elements from the first array. + +::: Examples + +~~~ +4 - .a +{"a":3} +1 +~~~ + +~~~ +. - ["xml", "yaml"] +["xml", "yaml", "json"] +["json"] +~~~ + +::: + +## Multiplication, division, modulo: `*`, `/`, `%` + +These infix operators behave as expected when given two numbers. +Division by zero raises an error. `x % y` computes x modulo y. + +Multiplying a string by a number produces the concatenation of +that string that many times. `"x" * 0` produces `""`. + +Dividing a string by another splits the first using the second +as separators. + +Multiplying two objects will merge them recursively: this works +like addition but if both objects contain a value for the +same key, and the values are objects, the two are merged with +the same strategy. + +::: Examples + +~~~ +10 / . * 3 +5 +6 +~~~ + +~~~ +. / ", " +"a, b,c,d, e" +["a","b,c,d","e"] +~~~ + +~~~ +{"k": {"a": 1, "b": 2}} * {"k": {"a": 0,"c": 3}} +null +{"k": {"a": 0, "b": 2, "c": 3}} +~~~ + +~~~ +.[] | (1 / .)? +[1,0,-1] +1 +-1 +~~~ + +::: + +## `abs` + +The builtin function `abs` is defined naively as: `if . < 0 then - . else . end`. + +For numeric input, this is the absolute value. See the +section on the identity filter for the implications of this +definition for numeric input. + +To compute the absolute value of a number as a floating point number, you may wish use `fabs`. + +::: Examples + +~~~ +map(abs) +[-10, -1.1, -1e-1] +[10,1.1,1e-1] +~~~ + +::: + +## `length` + +The builtin function `length` gets the length of various +different types of value: + +- The length of a **string** is the number of Unicode + codepoints it contains (which will be the same as its + JSON-encoded length in bytes if it's pure ASCII). + +- The length of a **number** is its absolute value. + +- The length of an **array** is the number of elements. + +- The length of an **object** is the number of key-value pairs. + +- The length of **null** is zero. + +- It is an error to use `length` on a **boolean**. + +::: Examples + +~~~ +.[] | length +[[1,2], "string", {"a":2}, null, -5] +2 +6 +1 +0 +5 +~~~ + +::: + +## `utf8bytelength` + +The builtin function `utf8bytelength` outputs the number of +bytes used to encode a string in UTF-8. + +::: Examples + +~~~ +utf8bytelength +"\u03bc" +2 +~~~ + +::: + +## `keys`, `keys_unsorted` + +The builtin function `keys`, when given an object, returns +its keys in an array. + +The keys are sorted "alphabetically", by unicode codepoint +order. This is not an order that makes particular sense in +any particular language, but you can count on it being the +same for any two objects with the same set of keys, +regardless of locale settings. + +When `keys` is given an array, it returns the valid indices +for that array: the integers from 0 to length-1. + +The `keys_unsorted` function is just like `keys`, but if +the input is an object then the keys will not be sorted, +instead the keys will roughly be in insertion order. + +::: Examples + +~~~ +keys +{"abc": 1, "abcd": 2, "Foo": 3} +["Foo", "abc", "abcd"] +~~~ + +~~~ +keys +[42,3,35] +[0,1,2] +~~~ + +::: + +## `has(key)` + +The builtin function `has` returns whether the input object +has the given key, or the input array has an element at the +given index. + +`has($key)` has the same effect as checking whether `$key` +is a member of the array returned by `keys`, although `has` +will be faster. + +::: Examples + +~~~ +map(has("foo")) +[{"foo": 42}, {}] +[true, false] +~~~ + +~~~ +map(has(2)) +[[0,1], ["a","b","c"]] +[false, true] +~~~ + +::: + +## `in` + +The builtin function `in` returns whether or not the input key is in the +given object, or the input index corresponds to an element +in the given array. It is, essentially, an inversed version +of `has`. + +::: Examples + +~~~ +.[] | in({"foo": 42}) +["foo", "bar"] +true +false +~~~ + +~~~ +map(in([0,1])) +[2, 0] +[false, true] +~~~ + +::: + +## `map(f)`, `map_values(f)` + +For any filter `f`, `map(f)` and `map_values(f)` apply `f` +to each of the values in the input array or object, that is, +to the values of `.[]`. + +In the absence of errors, `map(f)` always outputs an array +whereas `map_values(f)` outputs an array if given an array, +or an object if given an object. + +When the input to `map_values(f)` is an object, the output +object has the same keys as the input object except for +those keys whose values when piped to `f` produce no values +at all. + +The key difference between `map(f)` and `map_values(f)` is +that the former simply forms an array from all the values of +`($x|f)` for each value, `$x`, in the input array or object, +but `map_values(f)` only uses `first($x|f)`. + +Specifically, for object inputs, `map_values(f)` constructs +the output object by examining in turn the value of +`first(.[$k]|f)` for each key, `$k`, of the input. If this +expression produces no values, then the corresponding key +will be dropped; otherwise, the output object will have that +value at the key, `$k`. + +Here are some examples to clarify the behavior of `map` and +`map_values` when applied to arrays. These examples assume the +input is `[1]` in all cases: + + map(.+1) #=> [2] + map(., .) #=> [1,1] + map(empty) #=> [] + + map_values(.+1) #=> [2] + map_values(., .) #=> [1] + map_values(empty) #=> [] + +`map(f)` is equivalent to `[.[] | f]` and +`map_values(f)` is equivalent to `.[] |= f`. + +In fact, these are their implementations. + +::: Examples + +~~~ +map(.+1) +[1,2,3] +[2,3,4] +~~~ + +~~~ +map_values(.+1) +{"a": 1, "b": 2, "c": 3} +{"a": 2, "b": 3, "c": 4} +~~~ + +~~~ +map(., .) +[1,2] +[1,1,2,2] +~~~ + +~~~ +map_values(. // empty) +{"a": null, "b": true, "c": false} +{"b":true} +~~~ + +::: + +## `pick(pathexps)` + +Emit the projection of the input object or array defined by the +specified sequence of path expressions, such that if `p` is any +one of these specifications, then `(. | p)` will evaluate to the +same value as `(. | pick(pathexps) | p)`. For arrays, negative +indices and `.[m:n]` specifications should not be used. + +::: Examples + +~~~ +pick(.a, .b.c, .x) +{"a": 1, "b": {"c": 2, "d": 3}, "e": 4} +{"a":1,"b":{"c":2},"x":null} +~~~ + +~~~ +pick(.[2], .[0], .[0]) +[1,2,3,4] +[1,null,3] +~~~ + +::: + +## `path(path_expression)` + +Outputs array representations of the given path expression +in `.`. The outputs are arrays of strings (object keys) +and/or numbers (array indices). + +Path expressions are jq expressions like `.a`, but also `.[]`. +There are two types of path expressions: ones that can match +exactly, and ones that cannot. For example, `.a.b.c` is an +exact match path expression, while `.a[].b` is not. + +`path(exact_path_expression)` will produce the array +representation of the path expression even if it does not +exist in `.`, if `.` is `null` or an array or an object. + +`path(pattern)` will produce array representations of the +paths matching `pattern` if the paths exist in `.`. + +Note that the path expressions are not different from normal +expressions. The expression +`path(..|select(type=="boolean"))` outputs all the paths to +boolean values in `.`, and only those paths. + +::: Examples + +~~~ +path(.a[0].b) +null +["a",0,"b"] +~~~ + +~~~ +[path(..)] +{"a":[{"b":1}]} +[[],["a"],["a",0],["a",0,"b"]] +~~~ + +::: + +## `del(path_expression)` + +The builtin function `del` removes a key and its corresponding +value from an object. + +::: Examples + +~~~ +del(.foo) +{"foo": 42, "bar": 9001, "baz": 42} +{"bar": 9001, "baz": 42} +~~~ + +~~~ +del(.[1, 2]) +["foo", "bar", "baz"] +["foo"] +~~~ + +::: + +## `getpath(PATHS)` + +The builtin function `getpath` outputs the values in `.` found +at each path in `PATHS`. + +::: Examples + +~~~ +getpath(["a","b"]) +null +null +~~~ + +~~~ +[getpath(["a","b"], ["a","c"])] +{"a":{"b":0, "c":1}} +[0, 1] +~~~ + +::: + +## `setpath(PATHS; VALUE)` + +The builtin function `setpath` sets the `PATHS` in `.` to `VALUE`. + +::: Examples + +~~~ +setpath(["a","b"]; 1) +null +{"a": {"b": 1}} +~~~ + +~~~ +setpath(["a","b"]; 1) +{"a":{"b":0}} +{"a": {"b": 1}} +~~~ + +~~~ +setpath([0,"a"]; 1) +null +[{"a":1}] +~~~ + +::: + +## `delpaths(PATHS)` + +The builtin function `delpaths` deletes the `PATHS` in `.`. +`PATHS` must be an array of paths, where each path is an array +of strings and numbers. + +::: Examples + +~~~ +delpaths([["a","b"]]) +{"a":{"b":1},"x":{"y":2}} +{"a":{},"x":{"y":2}} +~~~ + +::: + +## `to_entries`, `from_entries`, `with_entries(f)` + +These functions convert between an object and an array of +key-value pairs. If `to_entries` is passed an object, then +for each `k: v` entry in the input, the output array +includes `{"key": k, "value": v}`. + +`from_entries` does the opposite conversion, and `with_entries(f)` +is a shorthand for `to_entries | map(f) | from_entries`, useful for +doing some operation to all keys and values of an object. +`from_entries` accepts `"key"`, `"Key"`, `"name"`, `"Name"`, +`"value"`, and `"Value"` as keys. + +::: Examples + +~~~ +to_entries +{"a": 1, "b": 2} +[{"key":"a", "value":1}, {"key":"b", "value":2}] +~~~ + +~~~ +from_entries +[{"key":"a", "value":1}, {"key":"b", "value":2}] +{"a": 1, "b": 2} +~~~ + +~~~ +with_entries(.key |= "KEY_" + .) +{"a": 1, "b": 2} +{"KEY_a": 1, "KEY_b": 2} +~~~ + +::: + +## `select(boolean_expression)` + +The function `select(f)` produces its input unchanged if +`f` returns true for that input, and produces no output +otherwise. + +It's useful for filtering lists: `[1,2,3] | map(select(. >= 2))` +will give you `[2,3]`. + +::: Examples + +~~~ +map(select(. >= 2)) +[1,5,3,0,7] +[5,3,7] +~~~ + +~~~ +.[] | select(.id == "second") +[{"id": "first", "val": 1}, {"id": "second", "val": 2}] +{"id": "second", "val": 2} +~~~ + +::: + +## `arrays`, `objects`, `iterables`, `booleans`, `numbers`, `normals`, `finites`, `strings`, `nulls`, `values`, `scalars` + +These built-ins select only inputs that are arrays, objects, +iterables (arrays or objects), booleans, numbers, normal +numbers, finite numbers, strings, null, non-null values, and +non-iterables, respectively. + +::: Examples + +~~~ +.[]|numbers +[[],{},1,"foo",null,true,false] +1 +~~~ + +::: + +## `empty` + +`empty` returns no results. None at all. Not even `null`. + +It's useful on occasion. You'll know if you need it :) + +::: Examples + +~~~ +1, empty, 2 +null +1 +2 +~~~ + +~~~ +[1,2,empty,3] +null +[1,2,3] +~~~ + +::: + +## `error`, `error(message)` + +Produces an error with the input value, or with the message +given as the argument. Errors can be caught with try/catch; +see below. + +::: Examples + +~~~ +try error catch . +"error message" +"error message" +~~~ + +~~~ +try error("invalid value: \(.)") catch . +42 +"invalid value: 42" +~~~ + +::: + +## `halt` + +Stops the jq program with no further outputs. jq will exit +with exit status `0`. + +## `halt_error`, `halt_error(exit_code)` + +Stops the jq program with no further outputs. The input will +be printed on `stderr` as raw output (i.e., strings will not +have double quotes) with no decoration, not even a newline. + +The given `exit_code` (defaulting to `5`) will be jq's exit +status. + +For example, `"Error: something went wrong\n"|halt_error(1)`. + +## `$__loc__` + +Produces an object with a "file" key and a "line" key, with +the filename and line number where `$__loc__` occurs, as +values. + +::: Examples + +~~~ +try error("\($__loc__)") catch . +null +"{\"file\":\"\",\"line\":1}" +~~~ + +::: + +## `paths`, `paths(node_filter)` + +`paths` outputs the paths to all the elements in its input +(except it does not output the empty list, representing . +itself). + +`paths(f)` outputs the paths to any values for which `f` is `true`. +That is, `paths(type == "number")` outputs the paths to all numeric +values. + +::: Examples + +~~~ +[paths] +[1,[[],{"a":2}]] +[[0],[1],[1,0],[1,1],[1,1,"a"]] +~~~ + +~~~ +[paths(type == "number")] +[1,[[],{"a":2}]] +[[0],[1,1,"a"]] +~~~ + +::: + +## `add`, `add(generator)` + +The filter `add` takes as input an array, and produces as +output the elements of the array added together. This might +mean summed, concatenated or merged depending on the types +of the elements of the input array - the rules are the same +as those for the `+` operator (described above). + +If the input is an empty array, `add` returns `null`. + +`add(generator)` operates on the given generator rather than +the input. + +::: Examples + +~~~ +add +["a","b","c"] +"abc" +~~~ + +~~~ +add +[1, 2, 3] +6 +~~~ + +~~~ +add +[] +null +~~~ + +~~~ +add(.[].a) +[{"a":3}, {"a":5}, {"b":6}] +8 +~~~ + +::: + +## `any`, `any(condition)`, `any(generator; condition)` + +The filter `any` takes as input an array of boolean values, +and produces `true` as output if any of the elements of +the array are `true`. + +If the input is an empty array, `any` returns `false`. + +The `any(condition)` form applies the given condition to the +elements of the input array. + +The `any(generator; condition)` form applies the given +condition to all the outputs of the given generator. + +::: Examples + +~~~ +any +[true, false] +true +~~~ + +~~~ +any +[false, false] +false +~~~ + +~~~ +any +[] +false +~~~ + +::: + +## `all`, `all(condition)`, `all(generator; condition)` + +The filter `all` takes as input an array of boolean values, +and produces `true` as output if all of the elements of +the array are `true`. + +The `all(condition)` form applies the given condition to the +elements of the input array. + +The `all(generator; condition)` form applies the given +condition to all the outputs of the given generator. + +If the input is an empty array, `all` returns `true`. + +::: Examples + +~~~ +all +[true, false] +false +~~~ + +~~~ +all +[true, true] +true +~~~ + +~~~ +all +[] +true +~~~ + +::: + +## `flatten`, `flatten(depth)` + +The filter `flatten` takes as input an array of nested arrays, +and produces a flat array in which all arrays inside the original +array have been recursively replaced by their values. You can pass +an argument to it to specify how many levels of nesting to flatten. + +`flatten(2)` is like `flatten`, but going only up to two +levels deep. + +::: Examples + +~~~ +flatten +[1, [2], [[3]]] +[1, 2, 3] +~~~ + +~~~ +flatten(1) +[1, [2], [[3]]] +[1, 2, [3]] +~~~ + +~~~ +flatten +[[]] +[] +~~~ + +~~~ +flatten +[{"foo": "bar"}, [{"foo": "baz"}]] +[{"foo": "bar"}, {"foo": "baz"}] +~~~ + +::: + +## `range(upto)`, `range(from; upto)`, `range(from; upto; by)` + +The `range` function produces a range of numbers. `range(4; 10)` +produces 6 numbers, from 4 (inclusive) to 10 (exclusive). The numbers +are produced as separate outputs. Use `[range(4; 10)]` to get a range as +an array. + +The one argument form generates numbers from 0 to the given +number, with an increment of 1. + +The two argument form generates numbers from `from` to `upto` +with an increment of 1. + +The three argument form generates numbers `from` to `upto` +with an increment of `by`. + +::: Examples + +~~~ +range(2; 4) +null +2 +3 +~~~ + +~~~ +[range(2; 4)] +null +[2,3] +~~~ + +~~~ +[range(4)] +null +[0,1,2,3] +~~~ + +~~~ +[range(0; 10; 3)] +null +[0,3,6,9] +~~~ + +~~~ +[range(0; 10; -1)] +null +[] +~~~ + +~~~ +[range(0; -5; -1)] +null +[0,-1,-2,-3,-4] +~~~ + +::: + +## `floor` + +The `floor` function returns the floor of its numeric input. + +::: Examples + +~~~ +floor +3.14159 +3 +~~~ + +::: + +## `sqrt` + +The `sqrt` function returns the square root of its numeric input. + +::: Examples + +~~~ +sqrt +9 +3 +~~~ + +::: + +## `tonumber` + +The `tonumber` function parses its input as a number. It +will convert correctly-formatted strings to their numeric +equivalent, leave numbers alone, and give an error on all other input. + +::: Examples + +~~~ +.[] | tonumber +[1, "1"] +1 +1 +~~~ + +::: + +## `tostring` + +The `tostring` function prints its input as a +string. Strings are left unchanged, and all other values are +JSON-encoded. + +::: Examples + +~~~ +.[] | tostring +[1, "1", [1]] +"1" +"1" +"[1]" +~~~ + +::: + +## `type` + +The `type` function returns the type of its argument as a +string, which is one of null, boolean, number, string, array +or object. + +::: Examples + +~~~ +map(type) +[0, false, [], {}, null, "hello"] +["number", "boolean", "array", "object", "null", "string"] +~~~ + +::: + +## `infinite`, `nan`, `isinfinite`, `isnan`, `isfinite`, `isnormal` + +Some arithmetic operations can yield infinities and "not a +number" (NaN) values. The `isinfinite` builtin returns `true` +if its input is infinite. The `isnan` builtin returns `true` +if its input is a NaN. The `infinite` builtin returns a +positive infinite value. The `nan` builtin returns a NaN. +The `isnormal` builtin returns true if its input is a normal +number. + +Note that division by zero raises an error. + +Currently most arithmetic operations operating on infinities, +NaNs, and sub-normals do not raise errors. + +::: Examples + +~~~ +.[] | (infinite * .) < 0 +[-1, 1] +true +false +~~~ + +~~~ +infinite, nan | type +null +"number" +"number" +~~~ + +::: + +## `sort`, `sort_by(path_expression)` + +The `sort` functions sorts its input, which must be an +array. Values are sorted in the following order: + +* `null` +* `false` +* `true` +* numbers +* strings, in alphabetical order (by unicode codepoint value) +* arrays, in lexical order +* objects + +The ordering for objects is a little complex: first they're +compared by comparing their sets of keys (as arrays in +sorted order), and if their keys are equal then the values +are compared key by key. + +`sort_by` may be used to sort by a particular field of an +object, or by applying any jq filter. `sort_by(f)` compares +two elements by comparing the result of `f` on each element. +When `f` produces multiple values, it firstly compares the +first values, and the second values if the first values are +equal, and so on. + +::: Examples + +~~~ +sort +[8,3,null,6] +[null,3,6,8] +~~~ + +~~~ +sort_by(.foo) +[{"foo":4, "bar":10}, {"foo":3, "bar":10}, {"foo":2, "bar":1}] +[{"foo":2, "bar":1}, {"foo":3, "bar":10}, {"foo":4, "bar":10}] +~~~ + +~~~ +sort_by(.foo, .bar) +[{"foo":4, "bar":10}, {"foo":3, "bar":20}, {"foo":2, "bar":1}, {"foo":3, "bar":10}] +[{"foo":2, "bar":1}, {"foo":3, "bar":10}, {"foo":3, "bar":20}, {"foo":4, "bar":10}] +~~~ + +::: + +## `group_by(path_expression)` + +`group_by(.foo)` takes as input an array, groups the +elements having the same `.foo` field into separate arrays, +and produces all of these arrays as elements of a larger +array, sorted by the value of the `.foo` field. + +Any jq expression, not just a field access, may be used in +place of `.foo`. The sorting order is the same as described +in the `sort` function above. + +::: Examples + +~~~ +group_by(.foo) +[{"foo":1, "bar":10}, {"foo":3, "bar":100}, {"foo":1, "bar":1}] +[[{"foo":1, "bar":10}, {"foo":1, "bar":1}], [{"foo":3, "bar":100}]] +~~~ + +::: + +## `min`, `max`, `min_by(path_exp)`, `max_by(path_exp)` + +Find the minimum or maximum element of the input array. + +The `min_by(path_exp)` and `max_by(path_exp)` functions allow +you to specify a particular field or property to examine, e.g. +`min_by(.foo)` finds the object with the smallest `foo` field. + +::: Examples + +~~~ +min +[5,4,2,7] +2 +~~~ + +~~~ +max_by(.foo) +[{"foo":1, "bar":14}, {"foo":2, "bar":3}] +{"foo":2, "bar":3} +~~~ + +::: + +## `unique`, `unique_by(path_exp)` + +The `unique` function takes as input an array and produces +an array of the same elements, in sorted order, with +duplicates removed. + +The `unique_by(path_exp)` function will keep only one element +for each value obtained by applying the argument. Think of it +as making an array by taking one element out of every group +produced by `group`. + +::: Examples + +~~~ +unique +[1,2,5,3,5,3,1,3] +[1,2,3,5] +~~~ + +~~~ +unique_by(.foo) +[{"foo": 1, "bar": 2}, {"foo": 1, "bar": 3}, {"foo": 4, "bar": 5}] +[{"foo": 1, "bar": 2}, {"foo": 4, "bar": 5}] +~~~ + +~~~ +unique_by(length) +["chunky", "bacon", "kitten", "cicada", "asparagus"] +["bacon", "chunky", "asparagus"] +~~~ + +::: + +## `reverse` + +This function reverses an array. + +::: Examples + +~~~ +reverse +[1,2,3,4] +[4,3,2,1] +~~~ + +::: + +## `contains(element)` + +The filter `contains(b)` will produce true if b is +completely contained within the input. A string B is +contained in a string A if B is a substring of A. An array B +is contained in an array A if all elements in B are +contained in any element in A. An object B is contained in +object A if all of the values in B are contained in the +value in A with the same key. All other types are assumed to +be contained in each other if they are equal. + +::: Examples + +~~~ +contains("bar") +"foobar" +true +~~~ + +~~~ +contains(["baz", "bar"]) +["foobar", "foobaz", "blarp"] +true +~~~ + +~~~ +contains(["bazzzzz", "bar"]) +["foobar", "foobaz", "blarp"] +false +~~~ + +~~~ +contains({foo: 12, bar: [{barp: 12}]}) +{"foo": 12, "bar":[1,2,{"barp":12, "blip":13}]} +true +~~~ + +~~~ +contains({foo: 12, bar: [{barp: 15}]}) +{"foo": 12, "bar":[1,2,{"barp":12, "blip":13}]} +false +~~~ + +::: + +## `indices(s)` + +Outputs an array containing the indices in `.` where `s` +occurs. The input may be an array, in which case if `s` is an +array then the indices output will be those where all elements +in `.` match those of `s`. + +::: Examples + +~~~ +indices(", ") +"a,b, cd, efg, hijk" +[3,7,12] +~~~ + +~~~ +indices(1) +[0,1,2,1,3,1,4] +[1,3,5] +~~~ + +~~~ +indices([1,2]) +[0,1,2,3,1,4,2,5,1,2,6,7] +[1,8] +~~~ + +::: + +## `index(s)`, `rindex(s)` + +Outputs the index of the first (`index`) or last (`rindex`) +occurrence of `s` in the input. + +::: Examples + +~~~ +index(", ") +"a,b, cd, efg, hijk" +3 +~~~ + +~~~ +index(1) +[0,1,2,1,3,1,4] +1 +~~~ + +~~~ +index([1,2]) +[0,1,2,3,1,4,2,5,1,2,6,7] +1 +~~~ + +~~~ +rindex(", ") +"a,b, cd, efg, hijk" +12 +~~~ + +~~~ +rindex(1) +[0,1,2,1,3,1,4] +5 +~~~ + +~~~ +rindex([1,2]) +[0,1,2,3,1,4,2,5,1,2,6,7] +8 +~~~ + +::: + +## `inside` + +The filter `inside(b)` will produce true if the input is +completely contained within b. It is, essentially, an +inversed version of `contains`. + +::: Examples + +~~~ +inside("foobar") +"bar" +true +~~~ + +~~~ +inside(["foobar", "foobaz", "blarp"]) +["baz", "bar"] +true +~~~ + +~~~ +inside(["foobar", "foobaz", "blarp"]) +["bazzzzz", "bar"] +false +~~~ + +~~~ +inside({"foo": 12, "bar":[1,2,{"barp":12, "blip":13}]}) +{"foo": 12, "bar": [{"barp": 12}]} +true +~~~ + +~~~ +inside({"foo": 12, "bar":[1,2,{"barp":12, "blip":13}]}) +{"foo": 12, "bar": [{"barp": 15}]} +false +~~~ + +::: + +## `startswith(str)` + +Outputs `true` if . starts with the given string argument. + +::: Examples + +~~~ +[.[]|startswith("foo")] +["fo", "foo", "barfoo", "foobar", "barfoob"] +[false, true, false, true, false] +~~~ + +::: + +## `endswith(str)` + +Outputs `true` if . ends with the given string argument. + +::: Examples + +~~~ +[.[]|endswith("foo")] +["foobar", "barfoo"] +[false, true] +~~~ + +::: + +## `combinations`, `combinations(n)` + +Outputs all combinations of the elements of the arrays in the +input array. If given an argument `n`, it outputs all combinations +of `n` repetitions of the input array. + +::: Examples + +~~~ +combinations +[[1,2], [3, 4]] +[1, 3] +[1, 4] +[2, 3] +[2, 4] +~~~ + +~~~ +combinations(2) +[0, 1] +[0, 0] +[0, 1] +[1, 0] +[1, 1] +~~~ + +::: + +## `ltrimstr(str)` + +Outputs its input with the given prefix string removed, if it +starts with it. + +::: Examples + +~~~ +[.[]|ltrimstr("foo")] +["fo", "foo", "barfoo", "foobar", "afoo"] +["fo","","barfoo","bar","afoo"] +~~~ + +::: + +## `rtrimstr(str)` + +Outputs its input with the given suffix string removed, if it +ends with it. + +::: Examples + +~~~ +[.[]|rtrimstr("foo")] +["fo", "foo", "barfoo", "foobar", "foob"] +["fo","","bar","foobar","foob"] +~~~ + +::: + +## `trim`, `ltrim`, `rtrim` + +`trim` trims both leading and trailing whitespace. + +`ltrim` trims only leading (left side) whitespace. + +`rtrim` trims only trailing (right side) whitespace. + +Whitespace characters are the usual `" "`, `"\n"` `"\t"`, `"\r"` +and also all characters in the Unicode character database with the +whitespace property. Note that what considers whitespace might +change in the future. + +::: Examples + +~~~ +trim, ltrim, rtrim +" abc " +"abc" +"abc " +" abc" +~~~ + +::: + +## `explode` + +Converts an input string into an array of the string's +codepoint numbers. + +::: Examples + +~~~ +explode +"foobar" +[102,111,111,98,97,114] +~~~ + +::: + +## `implode` + +The inverse of explode. + +::: Examples + +~~~ +implode +[65, 66, 67] +"ABC" +~~~ + +::: + +## `split(str)` + +Splits an input string on the separator argument. + +`split` can also split on regex matches when called with +two arguments (see the regular expressions section below). + +::: Examples + +~~~ +split(", ") +"a, b,c,d, e, " +["a","b,c,d","e",""] +~~~ + +::: + +## `join(str)` + +Joins the array of elements given as input, using the +argument as separator. It is the inverse of `split`: that is, +running `split("foo") | join("foo")` over any input string +returns said input string. + +Numbers and booleans in the input are converted to strings. +Null values are treated as empty strings. Arrays and objects +in the input are not supported. + +::: Examples + +~~~ +join(", ") +["a","b,c,d","e"] +"a, b,c,d, e" +~~~ + +~~~ +join(" ") +["a",1,2.3,true,null,false] +"a 1 2.3 true false" +~~~ + +::: + +## `ascii_downcase`, `ascii_upcase` + +Emit a copy of the input string with its alphabetic characters (a-z and A-Z) +converted to the specified case. + +::: Examples + +~~~ +ascii_upcase +"useful but not for é" +"USEFUL BUT NOT FOR é" +~~~ + +::: + +## `while(cond; update)` + +The `while(cond; update)` function allows you to repeatedly +apply an update to `.` until `cond` is false. + +Note that `while(cond; update)` is internally defined as a +recursive jq function. Recursive calls within `while` will +not consume additional memory if `update` produces at most one +output for each input. See advanced topics below. + +::: Examples + +~~~ +[while(.<100; .*2)] +1 +[1,2,4,8,16,32,64] +~~~ + +::: + +## `repeat(exp)` + +The `repeat(exp)` function allows you to repeatedly +apply expression `exp` to `.` until an error is raised. + +Note that `repeat(exp)` is internally defined as a +recursive jq function. Recursive calls within `repeat` will +not consume additional memory if `exp` produces at most one +output for each input. See advanced topics below. + +::: Examples + +~~~ +[repeat(.*2, error)?] +1 +[2] +~~~ + +::: + +## `until(cond; next)` + +The `until(cond; next)` function allows you to repeatedly +apply the expression `next`, initially to `.` then to its own +output, until `cond` is true. For example, this can be used +to implement a factorial function (see below). + +Note that `until(cond; next)` is internally defined as a +recursive jq function. Recursive calls within `until()` will +not consume additional memory if `next` produces at most one +output for each input. See advanced topics below. + +::: Examples + +~~~ +[.,1]|until(.[0] < 1; [.[0] - 1, .[1] * .[0]])|.[1] +4 +24 +~~~ + +::: + +## `recurse(f)`, `recurse`, `recurse(f; condition)` + +The `recurse(f)` function allows you to search through a +recursive structure, and extract interesting data from all +levels. Suppose your input represents a filesystem: + + {"name": "/", "children": [ + {"name": "/bin", "children": [ + {"name": "/bin/ls", "children": []}, + {"name": "/bin/sh", "children": []}]}, + {"name": "/home", "children": [ + {"name": "/home/stephen", "children": [ + {"name": "/home/stephen/jq", "children": []}]}]}]} + +Now suppose you want to extract all of the filenames +present. You need to retrieve `.name`, `.children[].name`, +`.children[].children[].name`, and so on. You can do this +with: + + recurse(.children[]) | .name + +When called without an argument, `recurse` is equivalent to +`recurse(.[]?)`. + +`recurse(f)` is identical to `recurse(f; true)` and can be +used without concerns about recursion depth. + +`recurse(f; condition)` is a generator which begins by +emitting . and then emits in turn .|f, .|f|f, .|f|f|f, ... so long +as the computed value satisfies the condition. For example, +to generate all the integers, at least in principle, one +could write `recurse(.+1; true)`. + +The recursive calls in `recurse` will not consume additional +memory whenever `f` produces at most a single output for each +input. + +::: Examples + +~~~ +recurse(.foo[]) +{"foo":[{"foo": []}, {"foo":[{"foo":[]}]}]} +{"foo":[{"foo":[]},{"foo":[{"foo":[]}]}]} +{"foo":[]} +{"foo":[{"foo":[]}]} +{"foo":[]} +~~~ + +~~~ +recurse +{"a":0,"b":[1]} +{"a":0,"b":[1]} +0 +[1] +1 +~~~ + +~~~ +recurse(. * .; . < 20) +2 +2 +4 +16 +~~~ + +::: + +## `walk(f)` + +The `walk(f)` function applies f recursively to every +component of the input entity. When an array is +encountered, f is first applied to its elements and then to +the array itself; when an object is encountered, f is first +applied to all the values and then to the object. In +practice, f will usually test the type of its input, as +illustrated in the following examples. The first example +highlights the usefulness of processing the elements of an +array of arrays before processing the array itself. The second +example shows how all the keys of all the objects within the +input can be considered for alteration. + +::: Examples + +~~~ +walk(if type == "array" then sort else . end) +[[4, 1, 7], [8, 5, 2], [3, 6, 9]] +[[1,4,7],[2,5,8],[3,6,9]] +~~~ + +~~~ +walk( if type == "object" then with_entries( .key |= sub( "^_+"; "") ) else . end ) +[ { "_a": { "__b": 2 } } ] +[{"a":{"b":2}}] +~~~ + +::: + +## `have_literal_numbers` + +This builtin returns true if jq's build configuration +includes support for preservation of input number literals. + +## `have_decnum` + +This builtin returns true if jq was built with "decnum", +which is the current literal number preserving numeric +backend implementation for jq. + +## `$JQ_BUILD_CONFIGURATION` + +This builtin binding shows the jq executable's build +configuration. Its value has no particular format, but +it can be expected to be at least the `./configure` +command-line arguments, and may be enriched in the +future to include the version strings for the build +tooling used. + +Note that this can be overridden in the command-line +with `--arg` and related options. + +## `$ENV`, `env` + +`$ENV` is an object representing the environment variables as +set when the jq program started. + +`env` outputs an object representing jq's current environment. + +At the moment there is no builtin for setting environment +variables. + +::: Examples + +~~~ +$ENV.PAGER +null +"less" +~~~ + +~~~ +env.PAGER +null +"less" +~~~ + +::: + +## `transpose` + +Transpose a possibly jagged matrix (an array of arrays). +Rows are padded with nulls so the result is always rectangular. + +::: Examples + +~~~ +transpose +[[1], [2,3]] +[[1,2],[null,3]] +~~~ + +::: + +## `bsearch(x)` + +`bsearch(x)` conducts a binary search for x in the input +array. If the input is sorted and contains x, then +`bsearch(x)` will return its index in the array; otherwise, if +the array is sorted, it will return (-1 - ix) where ix is an +insertion point such that the array would still be sorted +after the insertion of x at ix. If the array is not sorted, +`bsearch(x)` will return an integer that is probably of no +interest. + +::: Examples + +~~~ +bsearch(0) +[0,1] +0 +~~~ + +~~~ +bsearch(0) +[1,2,3] +-1 +~~~ + +~~~ +bsearch(4) as $ix | if $ix < 0 then .[-(1+$ix)] = 4 else . end +[1,2,3] +[1,2,3,4] +~~~ + +::: + +## String interpolation: `\(exp)` + +Inside a string, you can put an expression inside parens +after a backslash. Whatever the expression returns will be +interpolated into the string. + +::: Examples + +~~~ +"The input was \(.), which is one less than \(.+1)" +42 +"The input was 42, which is one less than 43" +~~~ + +::: + +## Convert to/from JSON + +The `tojson` and `fromjson` builtins dump values as JSON texts +or parse JSON texts into values, respectively. The `tojson` +builtin differs from `tostring` in that `tostring` returns strings +unmodified, while `tojson` encodes strings as JSON strings. + +::: Examples + +~~~ +[.[]|tostring] +[1, "foo", ["foo"]] +["1","foo","[\"foo\"]"] +~~~ + +~~~ +[.[]|tojson] +[1, "foo", ["foo"]] +["1","\"foo\"","[\"foo\"]"] +~~~ + +~~~ +[.[]|tojson|fromjson] +[1, "foo", ["foo"]] +[1,"foo",["foo"]] +~~~ + +::: + +## Format strings and escaping + +The `@foo` syntax is used to format and escape strings, +which is useful for building URLs, documents in a language +like HTML or XML, and so forth. `@foo` can be used as a +filter on its own, the possible escapings are: + +* `@text`: + + Calls `tostring`, see that function for details. + +* `@json`: + + Serializes the input as JSON. + +* `@html`: + + Applies HTML/XML escaping, by mapping the characters + `<>&'"` to their entity equivalents `<`, `>`, + `&`, `'`, `"`. + +* `@uri`: + + Applies percent-encoding, by mapping all reserved URI + characters to a `%XX` sequence. + +* `@urid`: + + The inverse of `@uri`, applies percent-decoding, by mapping + all `%XX` sequences to their corresponding URI characters. + +* `@csv`: + + The input must be an array, and it is rendered as CSV + with double quotes for strings, and quotes escaped by + repetition. + +* `@tsv`: + + The input must be an array, and it is rendered as TSV + (tab-separated values). Each input array will be printed as + a single line. Fields are separated by a single + tab (ascii `0x09`). Input characters line-feed (ascii `0x0a`), + carriage-return (ascii `0x0d`), tab (ascii `0x09`) and + backslash (ascii `0x5c`) will be output as escape sequences + `\n`, `\r`, `\t`, `\\` respectively. + +* `@sh`: + + The input is escaped suitable for use in a command-line + for a POSIX shell. If the input is an array, the output + will be a series of space-separated strings. + +* `@base64`: + + The input is converted to base64 as specified by RFC 4648. + +* `@base64d`: + + The inverse of `@base64`, input is decoded as specified by RFC 4648. + Note\: If the decoded string is not UTF-8, the results are undefined. + +This syntax can be combined with string interpolation in a +useful way. You can follow a `@foo` token with a string +literal. The contents of the string literal will *not* be +escaped. However, all interpolations made inside that string +literal will be escaped. For instance, + + @uri "https://www.google.com/search?q=\(.search)" + +will produce the following output for the input +`{"search":"what is jq?"}`: + + "https://www.google.com/search?q=what%20is%20jq%3F" + +Note that the slashes, question mark, etc. in the URL are +not escaped, as they were part of the string literal. + +::: Examples + +~~~ +@html +"This works if x < y" +"This works if x < y" +~~~ + +~~~ +@sh "echo \(.)" +"O'Hara's Ale" +"echo 'O'\\''Hara'\\''s Ale'" +~~~ + +~~~ +@base64 +"This is a message" +"VGhpcyBpcyBhIG1lc3NhZ2U=" +~~~ + +~~~ +@base64d +"VGhpcyBpcyBhIG1lc3NhZ2U=" +"This is a message" +~~~ + +::: + +## Dates + +jq provides some basic date handling functionality, with some +high-level and low-level builtins. In all cases these +builtins deal exclusively with time in UTC. + +The `fromdateiso8601` builtin parses datetimes in the ISO 8601 +format to a number of seconds since the Unix epoch +(1970-01-01T00:00:00Z). The `todateiso8601` builtin does the +inverse. + +The `fromdate` builtin parses datetime strings. Currently +`fromdate` only supports ISO 8601 datetime strings, but in the +future it will attempt to parse datetime strings in more +formats. + +The `todate` builtin is an alias for `todateiso8601`. + +The `now` builtin outputs the current time, in seconds since +the Unix epoch. + +Low-level jq interfaces to the C-library time functions are +also provided: `strptime`, `strftime`, `strflocaltime`, +`mktime`, `gmtime`, and `localtime`. Refer to your host +operating system's documentation for the format strings used +by `strptime` and `strftime`. Note: these are not necessarily +stable interfaces in jq, particularly as to their localization +functionality. + +The `gmtime` builtin consumes a number of seconds since the +Unix epoch and outputs a "broken down time" representation of +Greenwich Mean Time as an array of numbers representing +(in this order): the year, the month (zero-based), the day of +the month (one-based), the hour of the day, the minute of the +hour, the second of the minute, the day of the week, and the +day of the year -- all one-based unless otherwise stated. The +day of the week number may be wrong on some systems for dates +before March 1st 1900, or after December 31 2099. + +The `localtime` builtin works like the `gmtime` builtin, but +using the local timezone setting. + +The `mktime` builtin consumes "broken down time" +representations of time output by `gmtime` and `strptime`. + +The `strptime(fmt)` builtin parses input strings matching the +`fmt` argument. The output is in the "broken down time" +representation consumed by `mktime` and output by `gmtime`. + +The `strftime(fmt)` builtin formats a time (GMT) with the +given format. The `strflocaltime` does the same, but using +the local timezone setting. + +The format strings for `strptime` and `strftime` are described +in typical C library documentation. The format string for ISO +8601 datetime is `"%Y-%m-%dT%H:%M:%SZ"`. + +jq may not support some or all of this date functionality on +some systems. In particular, the `%u` and `%j` specifiers for +`strptime(fmt)` are not supported on macOS. + +::: Examples + +~~~ +fromdate +"2015-03-05T23:51:47Z" +1425599507 +~~~ + +~~~ +strptime("%Y-%m-%dT%H:%M:%SZ") +"2015-03-05T23:51:47Z" +[2015,2,5,23,51,47,4,63] +~~~ + +~~~ +strptime("%Y-%m-%dT%H:%M:%SZ")|mktime +"2015-03-05T23:51:47Z" +1425599507 +~~~ + +::: + +## SQL-Style Operators + +jq provides a few SQL-style operators. + +* `INDEX(stream; index_expression)`: + + This builtin produces an object whose keys are computed by + the given index expression applied to each value from the + given stream. + +* `JOIN($idx; stream; idx_expr; join_expr)`: + + This builtin joins the values from the given stream to the + given index. The index's keys are computed by applying the + given index expression to each value from the given stream. + An array of the value in the stream and the corresponding + value from the index is fed to the given join expression to + produce each result. + +* `JOIN($idx; stream; idx_expr)`: + + Same as `JOIN($idx; stream; idx_expr; .)`. + +* `JOIN($idx; idx_expr)`: + + This builtin joins the input `.` to the given index, applying + the given index expression to `.` to compute the index key. + The join operation is as described above. + +* `IN(s)`: + + This builtin outputs `true` if `.` appears in the given + stream, otherwise it outputs `false`. + +* `IN(source; s)`: + + This builtin outputs `true` if any value in the source stream + appears in the second stream, otherwise it outputs `false`. + +## `builtins` + +Returns a list of all builtin functions in the format `name/arity`. +Since functions with the same name but different arities are considered +separate functions, `all/0`, `all/1`, and `all/2` would all be present +in the list. + +# Conditionals and Comparisons + +## `==`, `!=` + +The expression 'a == b' will produce 'true' if the results of evaluating +a and b are equal (that is, if they represent equivalent JSON values) and +'false' otherwise. In particular, strings are never considered equal +to numbers. In checking for the equality of JSON objects, the ordering of keys +is irrelevant. If you're coming from JavaScript, please note that jq's `==` is like +JavaScript's `===`, the "strict equality" operator. + +!= is "not equal", and 'a != b' returns the opposite value of 'a == b' + +::: Examples + +~~~ +. == false +null +false +~~~ + +~~~ +. == {"b": {"d": (4 + 1e-20), "c": 3}, "a":1} +{"a":1, "b": {"c": 3, "d": 4}} +true +~~~ + +~~~ +.[] == 1 +[1, 1.0, "1", "banana"] +true +true +false +false +~~~ + +::: + +## if-then-else-end + +`if A then B else C end` will act the same as `B` if `A` +produces a value other than false or null, but act the same +as `C` otherwise. + +`if A then B end` is the same as `if A then B else . end`. +That is, the `else` branch is optional, and if absent is the +same as `.`. This also applies to `elif` with absent ending `else` branch. + +Checking for false or null is a simpler notion of +"truthiness" than is found in JavaScript or Python, but it +means that you'll sometimes have to be more explicit about +the condition you want. You can't test whether, e.g. a +string is empty using `if .name then A else B end`; you'll +need something like `if .name == "" then A else B end` instead. + +If the condition `A` produces multiple results, then `B` is evaluated +once for each result that is not false or null, and `C` is evaluated +once for each false or null. + +More cases can be added to an if using `elif A then B` syntax. + +::: Examples + +~~~ +if . == 0 then "zero" elif . == 1 then "one" else "many" end +2 +"many" +~~~ + +::: + +## `>`, `>=`, `<=`, `<` + +The comparison operators `>`, `>=`, `<=`, `<` return whether +their left argument is greater than, greater than or equal +to, less than or equal to or less than their right argument +(respectively). + +The ordering is the same as that described for `sort`, above. + +::: Examples + +~~~ +. < 5 +2 +true +~~~ + +::: + +## `and`, `or`, `not` + +jq supports the normal Boolean operators `and`, `or`, `not`. +They have the same standard of truth as if expressions - +`false` and `null` are considered "false values", and +anything else is a "true value". + +If an operand of one of these operators produces multiple +results, the operator itself will produce a result for each input. + +`not` is in fact a builtin function rather than an operator, +so it is called as a filter to which things can be piped +rather than with special syntax, as in `.foo and .bar | +not`. + +These three only produce the values `true` and `false`, and +so are only useful for genuine Boolean operations, rather +than the common Perl/Python/Ruby idiom of +"value_that_may_be_null or default". If you want to use this +form of "or", picking between two values rather than +evaluating a condition, see the `//` operator below. + +::: Examples + +~~~ +42 and "a string" +null +true +~~~ + +~~~ +(true, false) or false +null +true +false +~~~ + +~~~ +(true, true) and (true, false) +null +true +false +true +false +~~~ + +~~~ +[true, false | not] +null +[false, true] +~~~ + +::: + +## Alternative operator: `//` + +The `//` operator produces all the values of its left-hand +side that are neither `false` nor `null`. If the +left-hand side produces no values other than `false` or +`null`, then `//` produces all the values of its right-hand +side. + +A filter of the form `a // b` produces all the results of +`a` that are not `false` or `null`. If `a` produces no +results, or no results other than `false` or `null`, then `a +// b` produces the results of `b`. + +This is useful for providing defaults: `.foo // 1` will +evaluate to `1` if there's no `.foo` element in the +input. It's similar to how `or` is sometimes used in Python +(jq's `or` operator is reserved for strictly Boolean +operations). + +Note: `some_generator // defaults_here` is not the same +as `some_generator | . // defaults_here`. The latter will +produce default values for all non-`false`, non-`null` +values of the left-hand side, while the former will not. +Precedence rules can make this confusing. For example, in +`false, 1 // 2` the left-hand side of `//` is `1`, not +`false, 1` -- `false, 1 // 2` parses the same way as `false, +(1 // 2)`. In `(false, null, 1) | . // 42` the left-hand +side of `//` is `.`, which always produces just one value, +while in `(false, null, 1) // 42` the left-hand side is a +generator of three values, and since it produces a +value other `false` and `null`, the default `42` is not +produced. + +::: Examples + +~~~ +empty // 42 +null +42 +~~~ + +~~~ +.foo // 42 +{"foo": 19} +19 +~~~ + +~~~ +.foo // 42 +{} +42 +~~~ + +~~~ +(false, null, 1) // 42 +null +1 +~~~ + +~~~ +(false, null, 1) | . // 42 +null +42 +42 +1 +~~~ + +::: + +## try-catch + +Errors can be caught by using `try EXP catch EXP`. The first +expression is executed, and if it fails then the second is +executed with the error message. The output of the handler, +if any, is output as if it had been the output of the +expression to try. + +The `try EXP` form uses `empty` as the exception handler. + +::: Examples + +~~~ +try .a catch ". is not an object" +true +". is not an object" +~~~ + +~~~ +[.[]|try .a] +[{}, true, {"a":1}] +[null, 1] +~~~ + +~~~ +try error("some exception") catch . +true +"some exception" +~~~ + +::: + +## Breaking out of control structures + +A convenient use of try/catch is to break out of control +structures like `reduce`, `foreach`, `while`, and so on. + +For example: + + # Repeat an expression until it raises "break" as an + # error, then stop repeating without re-raising the error. + # But if the error caught is not "break" then re-raise it. + try repeat(exp) catch if .=="break" then empty else error + +jq has a syntax for named lexical labels to "break" or "go (back) to": + + label $out | ... break $out ... + +The `break $label_name` expression will cause the program to +act as though the nearest (to the left) `label $label_name` +produced `empty`. + +The relationship between the `break` and corresponding `label` +is lexical: the label has to be "visible" from the break. + +To break out of a `reduce`, for example: + + label $out | reduce .[] as $item (null; if .==false then break $out else ... end) + +The following jq program produces a syntax error: + + break $out + +because no label `$out` is visible. + +## Error Suppression / Optional Operator: `?` + +The `?` operator, used as `EXP?`, is shorthand for `try EXP`. + +::: Examples + +~~~ +[.[] | .a?] +[{}, true, {"a":1}] +[null, 1] +~~~ + +~~~ +[.[] | tonumber?] +["1", "invalid", "3", 4] +[1, 3, 4] +~~~ + +::: + +# Regular expressions + +jq uses the +[Oniguruma regular expression library](https://github.com/kkos/oniguruma/blob/master/doc/RE), +as do PHP, TextMate, Sublime Text, etc, so the +description here will focus on jq specifics. + +Oniguruma supports several flavors of regular expression, so it is important to know +that jq uses the ["Perl NG" (Perl with named groups)](https://github.com/kkos/oniguruma/blob/master/doc/SYNTAX.md) flavor. + +The jq regex filters are defined so that they can be used using +one of these patterns: + + STRING | FILTER(REGEX) + STRING | FILTER(REGEX; FLAGS) + STRING | FILTER([REGEX]) + STRING | FILTER([REGEX, FLAGS]) + +where: + +* STRING, REGEX, and FLAGS are jq strings and subject to jq string interpolation; +* REGEX, after string interpolation, should be a valid regular expression; +* FILTER is one of `test`, `match`, or `capture`, as described below. + +Since REGEX must evaluate to a JSON string, some characters that are needed +to form a regular expression must be escaped. For example, the regular expression +`\s` signifying a whitespace character would be written as `"\\s"`. + +FLAGS is a string consisting of one of more of the supported flags: + +* `g` - Global search (find all matches, not just the first) +* `i` - Case insensitive search +* `m` - Multi line mode (`.` will match newlines) +* `n` - Ignore empty matches +* `p` - Both s and m modes are enabled +* `s` - Single line mode (`^` -> `\A`, `$` -> `\Z`) +* `l` - Find longest possible matches +* `x` - Extended regex format (ignore whitespace and comments) + +To match a whitespace with the `x` flag, use `\s`, e.g. + + jq -n '"a b" | test("a\\sb"; "x")' + +Note that certain flags may also be specified within REGEX, e.g. + + jq -n '("test", "TEst", "teST", "TEST") | test("(?i)te(?-i)st")' + +evaluates to: `true`, `true`, `false`, `false`. + +## `test(val)`, `test(regex; flags)` + +Like `match`, but does not return match objects, only `true` or `false` +for whether or not the regex matches the input. + +::: Examples + +~~~ +test("foo") +"foo" +true +~~~ + +~~~ +.[] | test("a b c # spaces are ignored"; "ix") +["xabcd", "ABC"] +true +true +~~~ + +::: + +## `match(val)`, `match(regex; flags)` + +**match** outputs an object for each match it finds. Matches have +the following fields: + +* `offset` - offset in UTF-8 codepoints from the beginning of the input +* `length` - length in UTF-8 codepoints of the match +* `string` - the string that it matched +* `captures` - an array of objects representing capturing groups. + +Capturing group objects have the following fields: + +* `offset` - offset in UTF-8 codepoints from the beginning of the input +* `length` - length in UTF-8 codepoints of this capturing group +* `string` - the string that was captured +* `name` - the name of the capturing group (or `null` if it was unnamed) + +Capturing groups that did not match anything return an offset of -1 + +::: Examples + +~~~ +match("(abc)+"; "g") +"abc abc" +{"offset": 0, "length": 3, "string": "abc", "captures": [{"offset": 0, "length": 3, "string": "abc", "name": null}]} +{"offset": 4, "length": 3, "string": "abc", "captures": [{"offset": 4, "length": 3, "string": "abc", "name": null}]} +~~~ + +~~~ +match("foo") +"foo bar foo" +{"offset": 0, "length": 3, "string": "foo", "captures": []} +~~~ + +~~~ +match(["foo", "ig"]) +"foo bar FOO" +{"offset": 0, "length": 3, "string": "foo", "captures": []} +{"offset": 8, "length": 3, "string": "FOO", "captures": []} +~~~ + +~~~ +match("foo (?bar)? foo"; "ig") +"foo bar foo foo foo" +{"offset": 0, "length": 11, "string": "foo bar foo", "captures": [{"offset": 4, "length": 3, "string": "bar", "name": "bar123"}]} +{"offset": 12, "length": 8, "string": "foo foo", "captures": [{"offset": -1, "length": 0, "string": null, "name": "bar123"}]} +~~~ + +~~~ +[ match("."; "g")] | length +"abc" +3 +~~~ + +::: + +## `capture(val)`, `capture(regex; flags)` + +Collects the named captures in a JSON object, with the name +of each capture as the key, and the matched string as the +corresponding value. + +::: Examples + +~~~ +capture("(?[a-z]+)-(?[0-9]+)") +"xyzzy-14" +{ "a": "xyzzy", "n": "14" } +~~~ + +::: + +## `scan(regex)`, `scan(regex; flags)` + +Emit a stream of the non-overlapping substrings of the input +that match the regex in accordance with the flags, if any +have been specified. If there is no match, the stream is empty. +To capture all the matches for each input string, use the idiom +`[ expr ]`, e.g. `[ scan(regex) ]`. + +::: Examples + +~~~ +scan("c") +"abcdefabc" +"c" +"c" +~~~ + +::: + +## `split(regex; flags)` + +Splits an input string on each regex match. + +For backwards compatibility, when called with a single argument, +`split` splits on a string, not a regex. + +::: Examples + +~~~ +split(", *"; null) +"ab,cd, ef" +["ab","cd","ef"] +~~~ + +::: + +## `splits(regex)`, `splits(regex; flags)` + +These provide the same results as their `split` counterparts, +but as a stream instead of an array. + +::: Examples + +~~~ +splits(", *") +"ab,cd, ef, gh" +"ab" +"cd" +"ef" +"gh" +~~~ + +::: + +## `sub(regex; tostring)`, `sub(regex; tostring; flags)` + +Emit the string obtained by replacing the first match of +regex in the input string with `tostring`, after +interpolation. `tostring` should be a jq string or a stream +of such strings, each of which may contain references to +named captures. The named captures are, in effect, presented +as a JSON object (as constructed by `capture`) to +`tostring`, so a reference to a captured variable named "x" +would take the form: `"\(.x)"`. + +::: Examples + +~~~ +sub("[^a-z]*(?[a-z]+)"; "Z\(.x)"; "g") +"123abc456def" +"ZabcZdef" +~~~ + +~~~ +[sub("(?.)"; "\(.a|ascii_upcase)", "\(.a|ascii_downcase)")] +"aB" +["AB","aB"] +~~~ + +::: + +## `gsub(regex; tostring)`, `gsub(regex; tostring; flags)` + +`gsub` is like `sub` but all the non-overlapping occurrences of the regex are +replaced by `tostring`, after interpolation. If the second argument is a stream +of jq strings, then `gsub` will produce a corresponding stream of JSON strings. + +::: Examples + +~~~ +gsub("(?.)[^a]*"; "+\(.x)-") +"Abcabc" +"+A-+a-" +~~~ + +~~~ +[gsub("p"; "a", "b")] +"p" +["a","b"] +~~~ + +::: + +# Advanced features +Variables are an absolute necessity in most programming languages, but +they're relegated to an "advanced feature" in jq. + +In most languages, variables are the only means of passing around +data. If you calculate a value, and you want to use it more than once, +you'll need to store it in a variable. To pass a value to another part +of the program, you'll need that part of the program to define a +variable (as a function parameter, object member, or whatever) in +which to place the data. + +It is also possible to define functions in jq, although this is +is a feature whose biggest use is defining jq's standard library +(many jq functions such as `map` and `select` are in fact written +in jq). + +jq has reduction operators, which are very powerful but a bit +tricky. Again, these are mostly used internally, to define some +useful bits of jq's standard library. + +It may not be obvious at first, but jq is all about generators +(yes, as often found in other languages). Some utilities are +provided to help deal with generators. + +Some minimal I/O support (besides reading JSON from standard +input, and writing JSON to standard output) is available. + +Finally, there is a module/library system. + +## Variable / Symbolic Binding Operator: `... as $identifier | ...` + +In jq, all filters have an input and an output, so manual +plumbing is not necessary to pass a value from one part of a program +to the next. Many expressions, for instance `a + b`, pass their input +to two distinct subexpressions (here `a` and `b` are both passed the +same input), so variables aren't usually necessary in order to use a +value twice. + +For instance, calculating the average value of an array of numbers +requires a few variables in most languages - at least one to hold the +array, perhaps one for each element or for a loop counter. In jq, it's +simply `add / length` - the `add` expression is given the array and +produces its sum, and the `length` expression is given the array and +produces its length. + +So, there's generally a cleaner way to solve most problems in jq than +defining variables. Still, sometimes they do make things easier, so jq +lets you define variables using `expression as $variable`. All +variable names start with `$`. Here's a slightly uglier version of the +array-averaging example: + + length as $array_length | add / $array_length + +We'll need a more complicated problem to find a situation where using +variables actually makes our lives easier. + + +Suppose we have an array of blog posts, with "author" and "title" +fields, and another object which is used to map author usernames to +real names. Our input looks like: + + {"posts": [{"title": "First post", "author": "anon"}, + {"title": "A well-written article", "author": "person1"}], + "realnames": {"anon": "Anonymous Coward", + "person1": "Person McPherson"}} + +We want to produce the posts with the author field containing a real +name, as in: + + {"title": "First post", "author": "Anonymous Coward"} + {"title": "A well-written article", "author": "Person McPherson"} + +We use a variable, `$names`, to store the realnames object, so that we +can refer to it later when looking up author usernames: + + .realnames as $names | .posts[] | {title, author: $names[.author]} + +The expression `exp as $x | ...` means: for each value of expression +`exp`, run the rest of the pipeline with the entire original input, and +with `$x` set to that value. Thus `as` functions as something of a +foreach loop. + +Just as `{foo}` is a handy way of writing `{foo: .foo}`, so +`{$foo}` is a handy way of writing `{foo: $foo}`. + +Multiple variables may be declared using a single `as` expression by +providing a pattern that matches the structure of the input +(this is known as "destructuring"): + + . as {realnames: $names, posts: [$first, $second]} | ... + +The variable declarations in array patterns (e.g., `. as +[$first, $second]`) bind to the elements of the array in from +the element at index zero on up, in order. When there is no +value at the index for an array pattern element, `null` is +bound to that variable. + +Variables are scoped over the rest of the expression that defines +them, so + + .realnames as $names | (.posts[] | {title, author: $names[.author]}) + +will work, but + + (.realnames as $names | .posts[]) | {title, author: $names[.author]} + +won't. + +For programming language theorists, it's more accurate to +say that jq variables are lexically-scoped bindings. In +particular there's no way to change the value of a binding; +one can only setup a new binding with the same name, but which +will not be visible where the old one was. + +::: Examples + +~~~ +.bar as $x | .foo | . + $x +{"foo":10, "bar":200} +210 +~~~ + +~~~ +. as $i|[(.*2|. as $i| $i), $i] +5 +[10,5] +~~~ + +~~~ +. as [$a, $b, {c: $c}] | $a + $b + $c +[2, 3, {"c": 4, "d": 5}] +9 +~~~ + +~~~ +.[] as [$a, $b] | {a: $a, b: $b} +[[0], [0, 1], [2, 1, 0]] +{"a":0,"b":null} +{"a":0,"b":1} +{"a":2,"b":1} +~~~ + +::: + +## Destructuring Alternative Operator: `?//` + +The destructuring alternative operator provides a concise mechanism +for destructuring an input that can take one of several forms. + +Suppose we have an API that returns a list of resources and events +associated with them, and we want to get the user_id and timestamp of +the first event for each resource. The API (having been clumsily +converted from XML) will only wrap the events in an array if the resource +has multiple events: + + {"resources": [{"id": 1, "kind": "widget", "events": {"action": "create", "user_id": 1, "ts": 13}}, + {"id": 2, "kind": "widget", "events": [{"action": "create", "user_id": 1, "ts": 14}, {"action": "destroy", "user_id": 1, "ts": 15}]}]} + +We can use the destructuring alternative operator to handle this structural change simply: + + .resources[] as {$id, $kind, events: {$user_id, $ts}} ?// {$id, $kind, events: [{$user_id, $ts}]} | {$user_id, $kind, $id, $ts} + +Or, if we aren't sure if the input is an array of values or an object: + + .[] as [$id, $kind, $user_id, $ts] ?// {$id, $kind, $user_id, $ts} | ... + +Each alternative need not define all of the same variables, but all named +variables will be available to the subsequent expression. Variables not +matched in the alternative that succeeded will be `null`: + + .resources[] as {$id, $kind, events: {$user_id, $ts}} ?// {$id, $kind, events: [{$first_user_id, $first_ts}]} | {$user_id, $first_user_id, $kind, $id, $ts, $first_ts} + +Additionally, if the subsequent expression returns an error, the +alternative operator will attempt to try the next binding. Errors +that occur during the final alternative are passed through. + + [[3]] | .[] as [$a] ?// [$b] | if $a != null then error("err: \($a)") else {$a,$b} end + +::: Examples + +~~~ +.[] as {$a, $b, c: {$d, $e}} ?// {$a, $b, c: [{$d, $e}]} | {$a, $b, $d, $e} +[{"a": 1, "b": 2, "c": {"d": 3, "e": 4}}, {"a": 1, "b": 2, "c": [{"d": 3, "e": 4}]}] +{"a":1,"b":2,"d":3,"e":4} +{"a":1,"b":2,"d":3,"e":4} +~~~ + +~~~ +.[] as {$a, $b, c: {$d}} ?// {$a, $b, c: [{$e}]} | {$a, $b, $d, $e} +[{"a": 1, "b": 2, "c": {"d": 3, "e": 4}}, {"a": 1, "b": 2, "c": [{"d": 3, "e": 4}]}] +{"a":1,"b":2,"d":3,"e":null} +{"a":1,"b":2,"d":null,"e":4} +~~~ + +~~~ +.[] as [$a] ?// [$b] | if $a != null then error("err: \($a)") else {$a,$b} end +[[3]] +{"a":null,"b":3} +~~~ + +::: + +## Defining Functions + +You can give a filter a name using "def" syntax: + + def increment: . + 1; + +From then on, `increment` is usable as a filter just like a +builtin function (in fact, this is how many of the builtins +are defined). A function may take arguments: + + def map(f): [.[] | f]; + +Arguments are passed as _filters_ (functions with no +arguments), _not_ as values. The same argument may be +referenced multiple times with different inputs (here `f` is +run for each element of the input array). Arguments to a +function work more like callbacks than like value arguments. +This is important to understand. Consider: + + def foo(f): f|f; + 5|foo(.*2) + +The result will be 20 because `f` is `.*2`, and during the +first invocation of `f` `.` will be 5, and the second time it +will be 10 (5 * 2), so the result will be 20. Function +arguments are filters, and filters expect an input when +invoked. + +If you want the value-argument behaviour for defining simple +functions, you can just use a variable: + + def addvalue(f): f as $f | map(. + $f); + +Or use the short-hand: + + def addvalue($f): ...; + +With either definition, `addvalue(.foo)` will add the current +input's `.foo` field to each element of the array. Do note +that calling `addvalue(.[])` will cause the `map(. + $f)` part +to be evaluated once per value in the value of `.` at the call +site. + +Multiple definitions using the same function name are allowed. +Each re-definition replaces the previous one for the same +number of function arguments, but only for references from +functions (or main program) subsequent to the re-definition. +See also the section below on scoping. + +::: Examples + +~~~ +def addvalue(f): . + [f]; map(addvalue(.[0])) +[[1,2],[10,20]] +[[1,2,1], [10,20,10]] +~~~ + +~~~ +def addvalue(f): f as $x | map(. + $x); addvalue(.[0]) +[[1,2],[10,20]] +[[1,2,1,2], [10,20,1,2]] +~~~ + +::: + +## Scoping + +There are two types of symbols in jq: value bindings (a.k.a., +"variables"), and functions. Both are scoped lexically, +with expressions being able to refer only to symbols that +have been defined "to the left" of them. The only exception +to this rule is that functions can refer to themselves so as +to be able to create recursive functions. + +For example, in the following expression there is a binding +which is visible "to the right" of it, `... | .*3 as +$times_three | [. + $times_three] | ...`, but not "to the +left". Consider this expression now, `... | (.*3 as +$times_three | [. + $times_three]) | ...`: here the binding +`$times_three` is _not_ visible past the closing parenthesis. + +## `isempty(exp)` + +Returns true if `exp` produces no outputs, false otherwise. + +::: Examples + +~~~ +isempty(empty) +null +true +~~~ + +~~~ +isempty(.[]) +[] +true +~~~ + +~~~ +isempty(.[]) +[1,2,3] +false +~~~ + +::: + +## `limit(n; exp)` + +The `limit` function extracts up to `n` outputs from `exp`. + +::: Examples + +~~~ +[limit(3;.[])] +[0,1,2,3,4,5,6,7,8,9] +[0,1,2] +~~~ + +::: + +## `first(expr)`, `last(expr)`, `nth(n; expr)` + +The `first(expr)` and `last(expr)` functions extract the first +and last values from `expr`, respectively. + +The `nth(n; expr)` function extracts the nth value output by `expr`. +Note that `nth(n; expr)` doesn't support negative values of `n`. + +::: Examples + +~~~ +[first(range(.)), last(range(.)), nth(./2; range(.))] +10 +[0,9,5] +~~~ + +::: + +## `first`, `last`, `nth(n)` + +The `first` and `last` functions extract the first +and last values from any array at `.`. + +The `nth(n)` function extracts the nth value of any array at `.`. + +::: Examples + +~~~ +[range(.)]|[first, last, nth(5)] +10 +[0,9,5] +~~~ + +::: + +## `reduce` + +The `reduce` syntax allows you to combine all of the results of +an expression by accumulating them into a single answer. +The form is `reduce EXP as $var (INIT; UPDATE)`. +As an example, we'll pass `[1,2,3]` to this expression: + + reduce .[] as $item (0; . + $item) + +For each result that `.[]` produces, `. + $item` is run to +accumulate a running total, starting from 0 as the input value. +In this example, `.[]` produces the results `1`, `2`, and `3`, +so the effect is similar to running something like this: + + 0 | 1 as $item | . + $item | + 2 as $item | . + $item | + 3 as $item | . + $item + +::: Examples + +~~~ +reduce .[] as $item (0; . + $item) +[1,2,3,4,5] +15 +~~~ + +~~~ +reduce .[] as [$i,$j] (0; . + $i * $j) +[[1,2],[3,4],[5,6]] +44 +~~~ + +~~~ +reduce .[] as {$x,$y} (null; .x += $x | .y += [$y]) +[{"x":"a","y":1},{"x":"b","y":2},{"x":"c","y":3}] +{"x":"abc","y":[1,2,3]} +~~~ + +::: + +## `foreach` + +The `foreach` syntax is similar to `reduce`, but intended to +allow the construction of `limit` and reducers that produce +intermediate results. + +The form is `foreach EXP as $var (INIT; UPDATE; EXTRACT)`. +As an example, we'll pass `[1,2,3]` to this expression: + + foreach .[] as $item (0; . + $item; [$item, . * 2]) + +Like the `reduce` syntax, `. + $item` is run for each result +that `.[]` produces, but `[$item, . * 2]` is run for each +intermediate values. In this example, since the intermediate +values are `1`, `3`, and `6`, the `foreach` expression produces +`[1,2]`, `[2,6]`, and `[3,12]`. So the effect is similar +to running something like this: + + 0 | 1 as $item | . + $item | [$item, . * 2], + 2 as $item | . + $item | [$item, . * 2], + 3 as $item | . + $item | [$item, . * 2] + +When `EXTRACT` is omitted, the identity filter is used. +That is, it outputs the intermediate values as they are. + +::: Examples + +~~~ +foreach .[] as $item (0; . + $item) +[1,2,3,4,5] +1 +3 +6 +10 +15 +~~~ + +~~~ +foreach .[] as $item (0; . + $item; [$item, . * 2]) +[1,2,3,4,5] +[1,2] +[2,6] +[3,12] +[4,20] +[5,30] +~~~ + +~~~ +foreach .[] as $item (0; . + 1; {index: ., $item}) +["foo", "bar", "baz"] +{"index":1,"item":"foo"} +{"index":2,"item":"bar"} +{"index":3,"item":"baz"} +~~~ + +::: + +## Recursion + +As described above, `recurse` uses recursion, and any jq +function can be recursive. The `while` builtin is also +implemented in terms of recursion. + +Tail calls are optimized whenever the expression to the left of +the recursive call outputs its last value. In practice this +means that the expression to the left of the recursive call +should not produce more than one output for each input. + +For example: + + def recurse(f): def r: ., (f | select(. != null) | r); r; + + def while(cond; update): + def _while: + if cond then ., (update | _while) else empty end; + _while; + + def repeat(exp): + def _repeat: + exp, _repeat; + _repeat; + +## Generators and iterators + +Some jq operators and functions are actually generators in +that they can produce zero, one, or more values for each +input, just as one might expect in other programming +languages that have generators. For example, `.[]` +generates all the values in its input (which must be an +array or an object), `range(0; 10)` generates the integers +between 0 and 10, and so on. + +Even the comma operator is a generator, generating first +the values generated by the expression to the left of the +comma, then the values generated by the expression on the +right of the comma. + +The `empty` builtin is the generator that produces zero +outputs. The `empty` builtin backtracks to the preceding +generator expression. + +All jq functions can be generators just by using builtin +generators. It is also possible to construct new generators +using only recursion and the comma operator. If +recursive calls are "in tail position" then the +generator will be efficient. In the example below the +recursive call by `_range` to itself is in tail position. +The example shows off three advanced topics: tail recursion, +generator construction, and sub-functions. + +::: Examples + +~~~ +def range(init; upto; by): def _range: if (by > 0 and . < upto) or (by < 0 and . > upto) then ., ((.+by)|_range) else . end; if by == 0 then init else init|_range end | select((by > 0 and . < upto) or (by < 0 and . > upto)); range(0; 10; 3) +null +0 +3 +6 +9 +~~~ + +~~~ +def while(cond; update): def _while: if cond then ., (update | _while) else empty end; _while; [while(.<100; .*2)] +1 +[1,2,4,8,16,32,64] +~~~ + +::: + +# Math + +jq currently only has IEEE754 double-precision (64-bit) floating +point number support. + +Besides simple arithmetic operators such as `+`, jq also has most +standard math functions from the C math library. C math functions +that take a single input argument (e.g., `sin()`) are available as +zero-argument jq functions. C math functions that take two input +arguments (e.g., `pow()`) are available as two-argument jq +functions that ignore `.`. C math functions that take three input +arguments are available as three-argument jq functions that ignore +`.`. + +Availability of standard math functions depends on the +availability of the corresponding math functions in your operating +system and C math library. Unavailable math functions will be +defined but will raise an error. + +One-input C math functions: `acos` `acosh` `asin` `asinh` `atan` +`atanh` `cbrt` `ceil` `cos` `cosh` `erf` `erfc` `exp` `exp10` +`exp2` `expm1` `fabs` `floor` `gamma` `j0` `j1` `lgamma` `log` +`log10` `log1p` `log2` `logb` `nearbyint` `rint` `round` +`significand` `sin` `sinh` `sqrt` `tan` `tanh` `tgamma` `trunc` +`y0` `y1`. + +Two-input C math functions: `atan2` `copysign` `drem` `fdim` +`fmax` `fmin` `fmod` `frexp` `hypot` `jn` `ldexp` `modf` +`nextafter` `nexttoward` `pow` `remainder` `scalb` `scalbln` `yn`. + +Three-input C math functions: `fma`. + +See your system's manual for more information on each of these. + +# I/O + +At this time jq has minimal support for I/O, mostly in the +form of control over when inputs are read. Two builtins functions +are provided for this, `input` and `inputs`, that read from the +same sources (e.g., `stdin`, files named on the command-line) as +jq itself. These two builtins, and jq's own reading actions, can +be interleaved with each other. They are commonly used in combination +with the null input option `-n` to prevent one input from being read +implicitly. + +Two builtins provide minimal output capabilities, `debug`, and +`stderr`. (Recall that a jq program's output values are always +output as JSON texts on `stdout`.) The `debug` builtin can have +application-specific behavior, such as for executables that use +the libjq C API but aren't the jq executable itself. The `stderr` +builtin outputs its input in raw mode to stder with no additional +decoration, not even a newline. + +Most jq builtins are referentially transparent, and yield constant +and repeatable value streams when applied to constant inputs. +This is not true of I/O builtins. + +## `input` + +Outputs one new input. + +Note that when using `input` it is generally be necessary to +invoke jq with the `-n` command-line option, otherwise +the first entity will be lost. + + echo 1 2 3 4 | jq '[., input]' # [1,2] [3,4] + +## `inputs` + +Outputs all remaining inputs, one by one. + +This is primarily useful for reductions over a program's +inputs. Note that when using `inputs` it is generally necessary +to invoke jq with the `-n` command-line option, otherwise +the first entity will be lost. + + echo 1 2 3 | jq -n 'reduce inputs as $i (0; . + $i)' # 6 + +## `debug`, `debug(msgs)` + +These two filters are like `.` but have as a side-effect the +production of one or more messages on stderr. + +The message produced by the `debug` filter has the form + + ["DEBUG:",] + +where `` is a compact rendition of the input +value. This format may change in the future. + +The `debug(msgs)` filter is defined as `(msgs | debug | empty), .` +thus allowing great flexibility in the content of the message, +while also allowing multi-line debugging statements to be created. + +For example, the expression: + + 1 as $x | 2 | debug("Entering function foo with $x == \($x)", .) | (.+1) + +would produce the value 3 but with the following two lines +being written to stderr: + + ["DEBUG:","Entering function foo with $x == 1"] + ["DEBUG:",2] + +## `stderr` + +Prints its input in raw and compact mode to stderr with no +additional decoration, not even a newline. + +## `input_filename` + +Returns the name of the file whose input is currently being +filtered. Note that this will not work well unless jq is +running in a UTF-8 locale. + +## `input_line_number` + +Returns the line number of the input currently being filtered. + +# Streaming + +With the `--stream` option jq can parse input texts in a streaming +fashion, allowing jq programs to start processing large JSON texts +immediately rather than after the parse completes. If you have a +single JSON text that is 1GB in size, streaming it will allow you +to process it much more quickly. + +However, streaming isn't easy to deal with as the jq program will +have `[, ]` (and a few other forms) as inputs. + +Several builtins are provided to make handling streams easier. + +The examples below use the streamed form of `[0,[1]]`, which is +`[[0],0],[[1,0],1],[[1,0]],[[1]]`. + +Streaming forms include `[, ]` (to indicate any +scalar value, empty array, or empty object), and `[]` (to +indicate the end of an array or object). Future versions of jq +run with `--stream` and `--seq` may output additional forms such +as `["error message"]` when an input text fails to parse. + +## `truncate_stream(stream_expression)` + +Consumes a number as input and truncates the corresponding +number of path elements from the left of the outputs of the +given streaming expression. + +::: Examples + +~~~ +truncate_stream([[0],1],[[1,0],2],[[1,0]],[[1]]) +1 +[[0],2] +[[0]] +~~~ + +::: + +## `fromstream(stream_expression)` + +Outputs values corresponding to the stream expression's +outputs. + +::: Examples + +~~~ +fromstream(1|truncate_stream([[0],1],[[1,0],2],[[1,0]],[[1]])) +null +[2] +~~~ + +::: + +## `tostream` + +The `tostream` builtin outputs the streamed form of its input. + +::: Examples + +~~~ +. as $dot|fromstream($dot|tostream)|.==$dot +[0,[1,{"a":1},{"b":2}]] +true +~~~ + +::: + +# Assignment +Assignment works a little differently in jq than in most +programming languages. jq doesn't distinguish between references +to and copies of something - two objects or arrays are either +equal or not equal, without any further notion of being "the +same object" or "not the same object". + +If an object has two fields which are arrays, `.foo` and `.bar`, +and you append something to `.foo`, then `.bar` will not get +bigger, even if you've previously set `.bar = .foo`. If you're +used to programming in languages like Python, Java, Ruby, +JavaScript, etc. then you can think of it as though jq does a full +deep copy of every object before it does the assignment (for +performance it doesn't actually do that, but that's the general +idea). + +This means that it's impossible to build circular values in jq +(such as an array whose first element is itself). This is quite +intentional, and ensures that anything a jq program can produce +can be represented in JSON. + +All the assignment operators in jq have path expressions on the +left-hand side (LHS). The right-hand side (RHS) provides values +to set to the paths named by the LHS path expressions. + +Values in jq are always immutable. Internally, assignment works +by using a reduction to compute new, replacement values for `.` that +have had all the desired assignments applied to `.`, then +outputting the modified value. This might be made clear by this +example: `{a:{b:{c:1}}} | (.a.b|=3), .`. This will output +`{"a":{"b":3}}` and `{"a":{"b":{"c":1}}}` because the last +sub-expression, `.`, sees the original value, not the modified +value. + +Most users will want to use modification assignment operators, +such as `|=` or `+=`, rather than `=`. + +Note that the LHS of assignment operators refers to a value in +`.`. Thus `$var.foo = 1` won't work as expected (`$var.foo` is +not a valid or useful path expression in `.`); use `$var | .foo = +1` instead. + +Note too that `.a,.b=0` does not set `.a` and `.b`, but +`(.a,.b)=0` sets both. + +## Update-assignment: `|=` +This is the "update" operator `|=`. It takes a filter on the +right-hand side and works out the new value for the property +of `.` being assigned to by running the old value through this +expression. For instance, `(.foo, .bar) |= .+1` will build an +object with the `foo` field set to the input's `foo` plus 1, +and the `bar` field set to the input's `bar` plus 1. + +The left-hand side can be any general path expression; see `path()`. + +Note that the left-hand side of `|=` refers to a value in `.`. +Thus `$var.foo |= . + 1` won't work as expected (`$var.foo` is +not a valid or useful path expression in `.`); use `$var | +.foo |= . + 1` instead. + +If the right-hand side outputs no values (i.e., `empty`), then +the left-hand side path will be deleted, as with `del(path)`. + +If the right-hand side outputs multiple values, only the first +one will be used (COMPATIBILITY NOTE: in jq 1.5 and earlier +releases, it used to be that only the last one was used). + +::: Examples + +~~~ +(..|select(type=="boolean")) |= if . then 1 else 0 end +[true,false,[5,true,[true,[false]],false]] +[1,0,[5,1,[1,[0]],0]] +~~~ + +::: + +## Arithmetic update-assignment: `+=`, `-=`, `*=`, `/=`, `%=`, `//=` + +jq has a few operators of the form `a op= b`, which are all +equivalent to `a |= . op b`. So, `+= 1` can be used to +increment values, being the same as `|= . + 1`. + +::: Examples + +~~~ +.foo += 1 +{"foo": 42} +{"foo": 43} +~~~ + +::: + +## Plain assignment: `=` + +This is the plain assignment operator. Unlike the others, the +input to the right-hand side (RHS) is the same as the input to +the left-hand side (LHS) rather than the value at the LHS +path, and all values output by the RHS will be used (as shown +below). + +If the RHS of `=` produces multiple values, then for each such +value jq will set the paths on the left-hand side to the value +and then it will output the modified `.`. For example, +`(.a,.b) = range(2)` outputs `{"a":0,"b":0}`, then +`{"a":1,"b":1}`. The "update" assignment forms (see above) do +not do this. + +This example should show the difference between `=` and `|=`: + +Provide input `{"a": {"b": 10}, "b": 20}` to the programs + + .a = .b + +and + + .a |= .b + +The former will set the `a` field of the input to the `b` +field of the input, and produce the output `{"a": 20, "b": 20}`. +The latter will set the `a` field of the input to the `a` +field's `b` field, producing `{"a": 10, "b": 20}`. + +::: Examples + +~~~ +.a = .b +{"a": {"b": 10}, "b": 20} +{"a":20,"b":20} +~~~ + +~~~ +.a |= .b +{"a": {"b": 10}, "b": 20} +{"a":10,"b":20} +~~~ + +~~~ +(.a, .b) = range(3) +null +{"a":0,"b":0} +{"a":1,"b":1} +{"a":2,"b":2} +~~~ + +~~~ +(.a, .b) |= range(3) +null +{"a":0,"b":0} +~~~ + +::: + +## Complex assignments +Lots more things are allowed on the left-hand side of a jq assignment +than in most languages. We've already seen simple field accesses on +the left hand side, and it's no surprise that array accesses work just +as well: + + .posts[0].title = "JQ Manual" + +What may come as a surprise is that the expression on the left may +produce multiple results, referring to different points in the input +document: + + .posts[].comments |= . + ["this is great"] + +That example appends the string "this is great" to the "comments" +array of each post in the input (where the input is an object with a +field "posts" which is an array of posts). + +When jq encounters an assignment like 'a = b', it records the "path" +taken to select a part of the input document while executing a. This +path is then used to find which part of the input to change while +executing the assignment. Any filter may be used on the +left-hand side of an equals - whichever paths it selects from the +input will be where the assignment is performed. + +This is a very powerful operation. Suppose we wanted to add a comment +to blog posts, using the same "blog" input above. This time, we only +want to comment on the posts written by "stedolan". We can find those +posts using the "select" function described earlier: + + .posts[] | select(.author == "stedolan") + +The paths provided by this operation point to each of the posts that +"stedolan" wrote, and we can comment on each of them in the same way +that we did before: + + (.posts[] | select(.author == "stedolan") | .comments) |= + . + ["terrible."] + +# Comments + +You can write comments in your jq filters using `#`. + +A `#` character (not part of a string) starts a comment. +All characters from `#` to the end of the line are ignored. + +If the end of the line is preceded by an odd number of backslash +characters, the following line is also considered part of the +comment and is ignored. + +For example, the following code outputs `[1,3,4,7]` + + [ + 1, + # foo \ + 2, + # bar \\ + 3, + 4, # baz \\\ + 5, \ + 6, + 7 + # comment \ + comment \ + comment + ] + +Backslash continuing the comment on the next line can be useful +when writing the "shebang" for a jq script: + + #!/bin/sh -- + # total - Output the sum of the given arguments (or stdin) + # usage: total [numbers...] + # \ + exec jq --args -MRnf "$0" -- "$@" + + $ARGS.positional | + reduce ( + if . == [] + then inputs + else .[] + end | + . as $dot | + try tonumber catch false | + if not or isnan then + @json "total: Invalid number \($dot).\n" | halt_error(1) + end + ) as $n (0; . + $n) + +The `exec` line is considered a comment by jq, so it is ignored. +But it is not ignored by `sh`, since in `sh` a backslash at the +end of the line does not continue the comment. +With this trick, when the script is invoked as `total 1 2`, +`/bin/sh -- /path/to/total 1 2` will be run, and `sh` will then +run `exec jq --args -MRnf /path/to/total -- 1 2` replacing itself +with a `jq` interpreter invoked with the specified options (`-M`, +`-R`, `-n`, `--args`), that evaluates the current file (`$0`), +with the arguments (`$@`) that were passed to `sh`. + +# Modules + +jq has a library/module system. Modules are files whose names end +in `.jq`. + +Modules imported by a program are searched for in a default search +path (see below). The `import` and `include` directives allow the +importer to alter this path. + +Paths in the search path are subject to various substitutions. + +For paths starting with `~/`, the user's home directory is +substituted for `~`. + +For paths starting with `$ORIGIN/`, the directory where the jq +executable is located is substituted for `$ORIGIN`. + +For paths starting with `./` or paths that are `.`, the path of +the including file is substituted for `.`. For top-level programs +given on the command-line, the current directory is used. + +Import directives can optionally specify a search path to which +the default is appended. + +The default search path is the search path given to the `-L` +command-line option, else `["~/.jq", "$ORIGIN/../lib/jq", +"$ORIGIN/../lib"]`. + +Null and empty string path elements terminate search path +processing. + +A dependency with relative path `foo/bar` would be searched for in +`foo/bar.jq` and `foo/bar/bar.jq` in the given search path. This +is intended to allow modules to be placed in a directory along +with, for example, version control files, README files, and so on, +but also to allow for single-file modules. + +Consecutive components with the same name are not allowed to avoid +ambiguities (e.g., `foo/foo`). + +For example, with `-L$HOME/.jq` a module `foo` can be found in +`$HOME/.jq/foo.jq` and `$HOME/.jq/foo/foo.jq`. + +If `.jq` exists in the user's home directory, and is a file (not a +directory), it is automatically sourced into the main program. + +## `import RelativePathString as NAME [];` + +Imports a module found at the given path relative to a +directory in a search path. A `.jq` suffix will be added to +the relative path string. The module's symbols are prefixed +with `NAME::`. + +The optional metadata must be a constant jq expression. It +should be an object with keys like `homepage` and so on. At +this time jq only uses the `search` key/value of the metadata. +The metadata is also made available to users via the +`modulemeta` builtin. + +The `search` key in the metadata, if present, should have a +string or array value (array of strings); this is the search +path to be prefixed to the top-level search path. + +## `include RelativePathString [];` + +Imports a module found at the given path relative to a +directory in a search path as if it were included in place. A +`.jq` suffix will be added to the relative path string. The +module's symbols are imported into the caller's namespace as +if the module's content had been included directly. + +The optional metadata must be a constant jq expression. It +should be an object with keys like `homepage` and so on. At +this time jq only uses the `search` key/value of the metadata. +The metadata is also made available to users via the +`modulemeta` builtin. + +## `import RelativePathString as $NAME [];` + +Imports a JSON file found at the given path relative to a +directory in a search path. A `.json` suffix will be added to +the relative path string. The file's data will be available +as `$NAME::NAME`. + +The optional metadata must be a constant jq expression. It +should be an object with keys like `homepage` and so on. At +this time jq only uses the `search` key/value of the metadata. +The metadata is also made available to users via the +`modulemeta` builtin. + +The `search` key in the metadata, if present, should have a +string or array value (array of strings); this is the search +path to be prefixed to the top-level search path. + +## `module ;` + +This directive is entirely optional. It's not required for +proper operation. It serves only the purpose of providing +metadata that can be read with the `modulemeta` builtin. + +The metadata must be a constant jq expression. It should be +an object with keys like `homepage`. At this time jq doesn't +use this metadata, but it is made available to users via the +`modulemeta` builtin. + +## `modulemeta` + +Takes a module name as input and outputs the module's metadata +as an object, with the module's imports (including metadata) +as an array value for the `deps` key and the module's defined +functions as an array value for the `defs` key. + +Programs can use this to query a module's metadata, which they +could then use to, for example, search for, download, and +install missing dependencies. + +# Colors + +To configure alternative colors just set the `JQ_COLORS` +environment variable to colon-delimited list of partial terminal +escape sequences like `"1;31"`, in this order: + + - color for `null` + - color for `false` + - color for `true` + - color for numbers + - color for strings + - color for arrays + - color for objects + - color for object keys + +The default color scheme is the same as setting +`JQ_COLORS="0;90:0;39:0;39:0;39:0;32:1;39:1;39:1;34"`. + +This is not a manual for VT100/ANSI escapes. However, each of +these color specifications should consist of two numbers separated +by a semi-colon, where the first number is one of these: + + - 1 (bright) + - 2 (dim) + - 4 (underscore) + - 5 (blink) + - 7 (reverse) + - 8 (hidden) + +and the second is one of these: + + - 30 (black) + - 31 (red) + - 32 (green) + - 33 (yellow) + - 34 (blue) + - 35 (magenta) + - 36 (cyan) + - 37 (white) + diff --git a/docs/content/manual/manual.yml b/docs/content/manual/manual.yml deleted file mode 120000 index e19b54da4d..0000000000 --- a/docs/content/manual/manual.yml +++ /dev/null @@ -1 +0,0 @@ -v1.7/manual.yml \ No newline at end of file diff --git a/docs/filters/filter.lua b/docs/filters/filter.lua new file mode 100644 index 0000000000..063ca8fec7 --- /dev/null +++ b/docs/filters/filter.lua @@ -0,0 +1,89 @@ +--[[ +function dump(o) + if type(o) == 'table' then + local s = '{ ' + for k,v in pairs(o) do + if type(k) ~= 'number' then k = '"'..k..'"' end + s = s .. '['..k..'] = ' .. dump(v) .. ',' + end + return s .. '} ' + else + return tostring(o) + end +end +]]-- + +-- uppercase top-level headings for man pages +function Header(el) + if FORMAT == "man" and el.level == 1 then + return el:walk{Str = function(el) return pandoc.Str(string.upper(el.text)) end} + end +end + +-- inline code is assumed to be in jq +function Code(code) + code.classes[1] = "jq" + return code +end + +-- code blocks are assumed to be in jq if no other language is given +function CodeBlock(block) + if next(block.classes) == nil then + block.classes[1] = "jq" + return block + end +end + +function Div(el) + if el.classes:includes'Examples' then + local el = el:walk{CodeBlock = function(block) return example(block.text) end} + + if FORMAT == "html" then + local summary = pandoc.Plain{ + pandoc.RawInline("html", ""), pandoc.Str 'Examples', + pandoc.RawInline("html", "") + } + return { + pandoc.RawBlock("html", '
'), summary, el, + pandoc.RawBlock("html", '
') + } + end + return el.content + end +end + +function example(test) + local _, _, filter, input, output = test:find("([^\n]+)\n([^\n]+)\n(.*)") + + if FORMAT == "man" then + input = "echo '" .. input .. "'" + filter = "jq '" .. filter .. "'" + return pandoc.CodeBlock("$ " .. input .. " \\\n | " .. filter .. "\n" .. output) + end + + local url = "https://jqplay.org/jq?q=" .. encodeUrl(filter) .. "&j=" .. encodeUrl(input) + simple_table = pandoc.SimpleTable( + "", -- caption + {pandoc.AlignRight, pandoc.AlignLeft}, + {0, 0}, -- let pandoc determine col widths, + {}, -- headers + { + {pandoc.Strong("Filter"), pandoc.Code(filter, {class = "jq" })}, + {pandoc.Strong( "Input"), pandoc.Code( input, {class = "json"})}, + {pandoc.Strong("Output"), pandoc.Code(output, {class = "json"})}, + {pandoc.Link("Run", url), {}} + } + ) + local table = pandoc.utils.from_simple_table(simple_table) + if FORMAT == "html" then + table.classes = {"table", "table-borderless", "table-sm", "w-auto"} + end + return table +end + +function encodeUrl(str) + str = string.gsub(str, "\n", "\r\n") + str = string.gsub(str, "([^%w%.%- ])", function(c) return string.format("%%%02X", string.byte(c)) end) + str = string.gsub(str, " ", "+") + return str +end diff --git a/docs/filters/tests.lua b/docs/filters/tests.lua new file mode 100644 index 0000000000..cb0d70898d --- /dev/null +++ b/docs/filters/tests.lua @@ -0,0 +1,8 @@ +function Pandoc(el) + el.blocks:walk{Div = function(el) + if el.classes:includes'Examples' then + el:walk{CodeBlock = function(block) print(block.text .. "\0") end} + end + end} + os.exit(0) +end diff --git a/docs/filters/toc.lua b/docs/filters/toc.lua new file mode 100644 index 0000000000..efbefb30b5 --- /dev/null +++ b/docs/filters/toc.lua @@ -0,0 +1,8 @@ +function Pandoc(el) + el.blocks:walk{Header = function(el) + print(" - level: " .. el.level) + print(" title: '" .. pandoc.utils.stringify(el) .. "'") + print(" id: " .. el.identifier) + end} + os.exit(0) +end diff --git a/docs/man/epilogue.md b/docs/man/epilogue.md new file mode 100644 index 0000000000..4e6c921b21 --- /dev/null +++ b/docs/man/epilogue.md @@ -0,0 +1,9 @@ +# BUGS + +Presumably. Report them or discuss them at: + + https://github.com/jqlang/jq/issues + +# AUTHOR + +Stephen Dolan `` diff --git a/docs/man/prologue.md b/docs/man/prologue.md new file mode 100644 index 0000000000..6162714590 --- /dev/null +++ b/docs/man/prologue.md @@ -0,0 +1,30 @@ +--- +title: JQ(1) +--- + +# NAME + +jq -- Command-line JSON processor + +# SYNOPSIS + +`jq` [...] [...] + +`jq` can transform JSON in various ways, by selecting, iterating, +reducing and otherwise mangling JSON documents. For instance, +running the command `jq 'map(.price) | add'` will take an array of +JSON objects as input and return the sum of their "price" fields. + +`jq` can accept text input as well, but by default, `jq` reads a +stream of JSON entities (including numbers and other literals) from +`stdin`. Whitespace is only needed to separate entities such as 1 +and 2, and true and false. One or more may be specified, in +which case `jq` will read input from those instead. + +The are described in the [INVOKING JQ] section; they +mostly concern input and output formatting. The is written +in the jq language and specifies how to transform the input +file or document. + +# FILTERS + diff --git a/docs/manual_schema.yml b/docs/manual_schema.yml deleted file mode 100644 index 615efad196..0000000000 --- a/docs/manual_schema.yml +++ /dev/null @@ -1,60 +0,0 @@ -type: object -required: - - headline - - body - - manpage_intro - - manpage_epilogue - - sections -additionalProperties: false -properties: - headline: - type: string - body: - type: string - manpage_intro: - type: string - manpage_epilogue: - type: string - sections: - type: array - items: - type: object - required: - - title - additionalProperties: false - properties: - title: - type: string - body: - type: string - entries: - type: array - items: - type: object - required: - - title - - body - additionalProperties: false - properties: - title: - type: string - body: - type: string - examples: - type: array - items: - type: object - required: - - program - - input - - output - additionalProperties: false - properties: - program: - type: string - input: - type: string - output: - type: array - items: - type: string diff --git a/docs/templates/manual.html.j2 b/docs/templates/manual.html.j2 index 812a4233ad..1def2361c3 100644 --- a/docs/templates/manual.html.j2 +++ b/docs/templates/manual.html.j2 @@ -17,6 +17,13 @@
    + {%- for section in toc %} + {%- if section.level == 1 %} +
  • + {{ section.title }} +
    • + {%- endif %} + {%- endfor %} {%- for section in sections %}
  • {{ section.title }} @@ -107,6 +114,9 @@ integrity="sha384-xbzjoN6H5XHmAqoSSR42hZVRninPGx85y+XZQGlWxVu2y91lTmr/oD80i5cjeUBv" crossorigin="anonymous">