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 supports 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 argument 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.  Subsequent -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 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

       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)