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node/shebang

suggest correct usage of shebang

  • ⭐️ This rule is included in plugin:node/recommended preset.
  • ✒️ The --fix option on the command line can automatically fix some of the problems reported by this rule.

When we make a CLI tool with Node.js, we add bin field to package.json, then we add a shebang the entry file. This rule suggests correct usage of shebang.

Fixable: This rule is automatically fixable using the --fix flag on the command line.

📖 Rule Details

This rule looks up package.json file from each linting target file. Starting from the directory of the target file, it goes up ancestor directories until found.

If package.json was not found, this rule does nothing.

This rule checks bin field of package.json, then if a target file matches one of bin files, it checks whether or not there is a correct shebang. Otherwise it checks whether or not there is not a shebang.

The following patterns are considered problems for files in bin field of package.json:

console.log("hello"); /*error This file needs shebang "#!/usr/bin/env node".*/
#!/usr/bin/env node  /*error This file must not have Unicode BOM.*/
console.log("hello");
// If this file has Unicode BOM.
#!/usr/bin/env node  /*error This file must have Unix linebreaks (LF).*/
console.log("hello");
// If this file has Windows' linebreaks (CRLF).

The following patterns are considered problems for other files:

#!/usr/bin/env node   /*error This file needs no shebang.*/
console.log("hello");

The following patterns are not considered problems for files in bin field of package.json:

#!/usr/bin/env node
console.log("hello");

The following patterns are not considered problems for other files:

console.log("hello");

Options

{
    "node/shebang": ["error", {"convertPath": null}]
}

convertPath

If we use transpilers (e.g. Babel), perhaps the file path to a source code is never handled as a bin file. convertPath option tells to the rule, it needs to convert file paths.

For example:

{
    "rules": {
        "node/shebang": ["error", {
            "convertPath": {
                "src/**/*.jsx": ["^src/(.+?)\\.jsx$", "lib/$1.js"]
            }
        }]
    }
}

This option has the following shape: <targetFiles>: [<fromRegExp>, <toString>]

targetFiles is a glob pattern. It converts paths which are matched to the pattern with the following way.

path.replace(new RegExp(fromRegExp), toString);

So on this example, src/a/foo.jsx is handled as lib/a/foo.js.

The convertPath option can be an array as well.

For example:

{
    "rules": {
        "node/shebang": ["error", {
            "convertPath": [
                {
                    "include": ["src/**/*.js"],
                    "exclude": ["**/*.spec.js"],
                    "replace": ["^src/(.+)$", "lib/$1"]
                }
            ]
        }]
    }
}

In this style, this option has the following shape as the same expression as above: {include: [<targetFiles>], replace: [<fromRegExp>, <toString>]}. In addition, we can specify glob patterns to exclude files.

Shared Settings

The following options can be set by shared settings. Several rules have the same option, but we can set this option at once.

  • convertPath

For Example:

{
    "settings": {
        "node": {
            "convertPath": {
                "src/**/*.jsx": ["^src/(.+?)\\.jsx$", "lib/$1.js"]
            }
        }
    },
    "rules": {
        "node/shebang": "error"
    }
}

🔎 Implementation