um

um is a command-line utility for creating and maintaining your own set of man-like help pages. It is available for MacOS (via Homebrew) and Linux (via AUR in Arch, otherwise via Homebrew, which is now on Linux).

Why?

Have you seen how long curl's man page is? How many times have you gone through it trying to figure out how to make a POST request?

Man pages are written to be comprehensive, but what humans really need are the bullet points. Use um to write your own man-like help pages that reflect what you've learned about a command so far. That way you have an easy reference for the things you already know are useful.

An Example

Say you've just reminded yourself how grep works for the third time this month. You'd like to hold on to that precious knowledge so you don't have to go digging through the grep man page again. You can do that with um:

$ um edit grep

This will open your text editor, allowing you to record everything you want to remember about grep. Once you've saved what you've written, you can pull it up again as easily as you would any man page:

$ um grep

This will open your pager with whatever you might have for grep, say:

GREP(shell)                                                        GREP(shell)


NAME
       grep -- Print lines matching a pattern

SYNOPSIS
       grep [OPTIONS...] pattern [FILE...]

REGEX SYNTAX
       .      Matches any character.

       ^      Anchors pattern to beginning of line.

       $      Anchors pattern to end of line.

       []     Character set.  ^ for negation, - for range.

OPTIONS
       -r     Recursively search listed directories.

       -E     Force grep to behave as egrep, accepting extended REGEXes.



Um Pages                      September 26, 2017                   GREP(shell)

um supports several additional sub-commands. Among them are:

• um list, which lists all the um pages you already have.
• um rm, which removes an existing um page.
• um topic, which switches between topic namespaces for your pages, allowing you to keep a separate set of um pages for css properties, for example.

Um Page Format

Man pages were historically typeset using the roff typesetting system. roff was basically an early LaTeX. Writing man pages using roff today is not very fun or intuitive.

Happily, the Kramdown library can be used to convert Markdown documents to roff-like man pages. (Previously, um used Pandoc. See UPGRADE.md if the switch to Kramdown has broken your um pages.) By default, um expects you to write your um pages in Markdown so that it can convert them and pass them to the man program to view. You can, however, elect to just write your um pages as .txt files and view them without going through the man program.

Below is the Markdown source that produced the grep listing above. Except for the Kramdown-specific attribute syntax (all the fiddly curly brace bits), it's all just Markdown:

# grep -- Print lines matching a pattern
{:data-section="shell"}
{:data-date="September 26, 2017"}
{:data-extra="Um Pages"}
{::comment}
^ The Kramdown "attribute list" which provides metadata for the page.
The first heading must include the name of the command and a summary.
{:/}

## SYNOPSIS
{::comment}Top level Markdown headings become man section headings.{:/}
**grep** [OPTIONS...] *pattern* [FILE...]

## REGEX SYNTAX
{::comment}Here we're using a "definition list" to get that man page look.{:/}

`.`
: Matches any character.

`^`
: Anchors pattern to beginning of line.

`$`
: Anchors pattern to end of line.

`[]`
: Character set. ^ for negation, - for range.

## OPTIONS
`-r`
: Recursively search listed directories.

`-E`
: Force grep to behave as egrep, accepting extended REGEXes.

See Configuration below for more information on changing the default um page format. See the Kramdown Man Converter Documentation for more information about Kramdown's flavor of Markdown and the formatting options available to you when you are writing a man page.

um's own man pages are written in Markdown and converted using Kramdown, so they could also make a good reference.

Installation

• MacOS/Linux: um is available via Homebrew:

$ brew install um

• Arch Linux: um is available via the AUR in two versions: the release version um and the latest master um-git

Post-Installation

A bash completion script for um is installed to /usr/local/etc/bash_completion.d, assuming you're using the default brew prefix. You may need to add the following lines to your ~/.bash_profile to enable the completion:

if [ -f $(brew --prefix)/etc/bash_completion.d/um-completion.sh ]; then
  . $(brew --prefix)/etc/bash_completion.d/um-completion.sh
fi

Help

Refer to um help for comprehensive documentation of the sub-commands and options available for um. Man pages are also available.

Configuration

You can configure um using a file called umconfig placed in a folder called .um in your home directory. The syntax for setting an option is as follows:

<option> = <value>
e.g.
pager = less

You can set values for pager, editor, default_topic, pages_directory, and pages_ext. The defaults for these options are less, vi, shell, ~/.um, and .md respectively. Before falling back to the defaults, um will attempt to read the values for pager and editor from the shell environment (i.e. the PAGER and EDITOR environment variables) if they are not specified in umconfig.

Option	Default	Meaning
pager	less	"Use this pager to view um pages."
editor	vi	"Use this editor to edit um pages."
default_topic	shell	Current topic if none is set.
pages_directory	~/.um	Where to store um pages.
pages_ext	.md	Unless .md, just the extension for your um pages.

The pager configuration option is only used when pages_ext is not .md (the default). When pages_ext is .md, then um runs the pages through Kramdown before passing them to man. The pager used by man is determined by the PAGER and MANPAGER environment variables. See the man page for man for more information.

So, if you wanted to store your um pages in your Dropbox folder, and you prefer emacs to vim, your config file might look like the following:

editor = emacs
pages_directory = /Users/myusername/Dropbox/um

You can print the current configuration using um config.

Finally, if you want to store your umconfig file in a different location, you can specify a new .um directory using the UMCONFIG_HOME environment variable. Adding export UMCONFIG_HOME = ~/foo/bar to your .bash_profile, for example, will cause um to look for a file called umconfig under ~/foo/bar instead of the default ~/.um.

Specifying UMCONFIG_HOME also changes where um looks for template files (see next section).

Page Templating

If you place a file called template.md in ~/.um, that file will serve as the basis for any new um pages you create (when pages_ext is set to .md). If you have pages_ext set to something else, perhaps .txt, then you should create a template file called template.txt.

The template file is preprocessed so that the following variables are replaced before the file is used to create a new um page:

Variable	Substitution
$name	The name of the page, which you specify when you call um edit <page name>.
$NAME	The same as above, but uppercase.
$topic	The name of the current topic.
$time	The current time in RFC2822 format.
$date	The current date as Month Day, Year.

If you do not have an appropriate template in your ~/.um directory, um falls back to using its default templates. um ships with a default template for .md um pages and .txt um pages.

Tips

If you want to reset the topic to its default whenever you start a new shell, you can place the following line in your .bash_profile or .bashrc:

um topic -d