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% SHELLCHECK(1) Shell script analysis tool

NAME

shellcheck - Shell script analysis tool

SYNOPSIS

shellcheck [OPTIONS...] FILES...

DESCRIPTION

ShellCheck is a static analysis and linting tool for sh/bash scripts. It's mainly focused on handling typical beginner and intermediate level syntax errors and pitfalls where the shell just gives a cryptic error message or strange behavior, but it also reports on a few more advanced issues where corner cases can cause delayed failures.

ShellCheck gives shell specific advice. Consider the line:

(( area = 3.14*r*r ))

  • For scripts starting with #!/bin/sh (or when using -s sh), ShellCheck will warn that (( .. )) is not POSIX compliant (similar to checkbashisms).

  • For scripts starting with #!/bin/bash (or using -s bash), ShellCheck will warn that decimals are not supported.

  • For scripts starting with #!/bin/ksh (or using -s ksh), ShellCheck will not warn at all, as ksh supports decimals in arithmetic contexts.

OPTIONS

-e\ CODE1[,CODE2...],\ **--exclude=**CODE1[,CODE2...]

: Explicitly exclude the specified codes from the report. Subsequent -e options are cumulative, but all the codes can be specified at once, comma-separated as a single argument.

-f FORMAT, **--format=**FORMAT

: Specify the output format of shellcheck, which prints its results in the standard output. Subsequent -f options are ignored, see FORMATS below for more information.

-s\ shell,\ **--shell=**shell

: Specify Bourne shell dialect. Valid values are sh, bash and ksh. The default is to use the file's shebang, or bash if the target shell can't be determined.

-V\ version,\ --version

: Print version and exit.

FORMATS

tty

: Plain text, human readable output. This is the default.

gcc

: GCC compatible output. Useful for editors that support compiling and showing syntax errors.

For example, in Vim, `:set makeprg=shellcheck\ -f\ gcc\ %` will allow
using `:make` to check the script, and `:cnext` to jump to the next error.

    <file>:<line>:<column>: <type>: <message>

checkstyle

: Checkstyle compatible XML output. Supported directly or through plugins by many IDEs and build monitoring systems.

    <?xml version='1.0' encoding='UTF-8'?>
    <checkstyle version='4.3'>
      <file name='file'>
        <error
          line='line'
          column='column'
          severity='severity'
          message='message'
          source='ShellCheck.SC####' />
        ...
      </file>
      ...
    </checkstyle>

json

: Json is a popular serialization format that is more suitable for web applications. ShellCheck's json is compact and contains only the bare minimum.

    [
      {
        "file": "filename",
        "line": lineNumber,
        "column": columnNumber,
        "level": "severitylevel",
        "code": errorCode,
        "message": "warning message"
      },
      ...
    ]

DIRECTIVES

ShellCheck directives can be specified as comments in the shell script before a command or block:

# shellcheck key=value key=value
command-or-structure

For example, to suppress SC2035 about using ./*.jpg:

# shellcheck disable=SC2035
echo "Files: " *.jpg

Here a shell brace group is used to suppress on multiple lines:

# shellcheck disable=SC2016
{
  echo 'Modifying $PATH'
  echo 'PATH=foo:$PATH' >> ~/.bashrc
}

Valid keys are:

disable : Disables a comma separated list of error codes for the following command. The command can be a simple command like echo foo, or a compound command like a function definition, subshell block or loop.

AUTHOR

ShellCheck is written and maintained by Vidar Holen.

REPORTING BUGS

Bugs and issues can be reported on GitHub:

https://github.com/koalaman/shellcheck/issues

SEE ALSO

sh(1) bash(1)