shellcheck/shellcheck.1.md

% 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

Print version information and exit.

-x,\ -external-sources

Follow 'source' statements even when the file is not specified as input. By default, shellcheck will only follow files specified on the command line. This option allows following any file the script may source.

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

COPYRIGHT

Copyright 2012-2015, Vidar Holen. Licensed under the GNU General Public License version 3 or later, see http://gnu.org/licenses/gpl.html

SEE ALSO

sh(1) bash(1)