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 this 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  sup‐
         ports decimals in arithmetic contexts.

OPTIONS

       -C[WHEN], --color[=WHEN]
              For TTY output, enable colors always, never or auto.  The default is auto.  --color without an ar‐
              gument is equivalent to --color=always.

       -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.  Subse‐
              quent -f options are ignored, see FORMATS below for more information.

       -s shell, --shell=shell
              Specify Bourne shell dialect.  Valid values are sh, bash, dash 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 (plus /dev/null).  This option allows follow‐
              ing 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

       To tell ShellCheck where to look for an otherwise dynamically determined file:

              # shellcheck source=./lib.sh
              source "$(find_install_dir)/lib.sh"

       Here a shell brace group is used to suppress a warning 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.

       source Overrides the filename included by a source/.  statement.  This can be  used  to  tell  shellcheck
              where to look for a file whose name is determined at runtime, or to skip a source by telling it to
              use /dev/null.

ENVIRONMENT VARIABLES

       The environment variable SHELLCHECK_OPTS can be set with default flags:

              export SHELLCHECK_OPTS='--shell=bash --exclude=SC2016'

       Its value will be split on spaces and prepended to the command line on each invocation.

RETURN VALUES

       ShellCheck uses the follow exit codes:

       • 0: All files successfully scanned with no issues.

       • 1: All files successfully scanned with some issues.

       • 2: Some files could not be processed (e.g.  file not found).

       • 3: ShellCheck was invoked with bad syntax (e.g.  unknown flag).

       • 4: ShellCheck was invoked with bad options (e.g.  unknown formatter).

LOCALE

       This  version of ShellCheck is only available in English.  All files are leniently decoded as UTF-8, with
       a fallback of ISO-8859-1 for invalid sequences.  LC_CTYPE is respected for output, and defaults to  UTF-8
       for locales where encoding is unspecified (such as the C locale).

       Windows  users seeing commitBuffer: invalid argument (invalid character) should set their terminal to use
       UTF-8 with chcp 65001.

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)

Shell script analysis tool                                                                         SHELLCHECK(1)