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SHELLCHECK(1) General Commands Manual SHELLCHECK(1) 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 check- bashisms). • 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 con- texts. OPTIONS -a, --check-sourced Emit warnings in sourced files. Normally, shellcheck will only warn about issues in the specified files. With this option, any issues in sourced files will also be reported. -C[WHEN], --color[=WHEN] For TTY output, enable colors always, never or auto. The de- fault is auto. --color without an argument is equivalent to --color=always. -i CODE1[,CODE2...], --include=CODE1[,CODE2...] Explicitly include only the specified codes in the report. Sub- sequent -i options are cumulative, but all the codes can be specified at once, comma-separated as a single argument. In- clude options override any provided exclude options. -e CODE1[,CODE2...], --exclude=CODE1[,CODE2...] Explicitly exclude the specified codes from the report. Subse- quent -e options are cumulative, but all the codes can be speci- fied at once, comma-separated as a single argument. --extended-analysis=true/false Enable/disable Dataflow Analysis to identify more issues (de- fault true). If ShellCheck uses too much CPU/RAM when checking scripts with several thousand lines of code, extended analysis can be disabled with this flag or a directive. This flag over- rides directives and rc files. -f FORMAT, --format=FORMAT Specify the output format of shellcheck, which prints its re- sults in the standard output. Subsequent -f options are ig- nored, see FORMATS below for more information. --list-optional Output a list of known optional checks. These can be enabled with -o flags or enable directives. --norc Don't try to look for .shellcheckrc configuration files. --rcfile RCFILE Prefer the specified configuration file over searching for one in the default locations. -o NAME1[,NAME2...], --enable=NAME1[,NAME2...] Enable optional checks. The special name all enables all of them. Subsequent -o options accumulate. This is equivalent to specifying enable directives. -P SOURCEPATH, --source-path=SOURCEPATH Specify paths to search for sourced files, separated by : on Unix and ; on Windows. This is equivalent to specifying search-path directives. -s shell, --shell=shell Specify Bourne shell dialect. Valid values are sh, bash, dash, ksh, and busybox. The default is to deduce the shell from the file's shell directive, shebang, or .bash/.bats/.dash/.ksh ex- tension, in that order. sh refers to POSIX sh (not the sys- tem's), and will warn of portability issues. -S SEVERITY, --severity=severity Specify minimum severity of errors to consider. Valid values in order of severity are error, warning, info and style. The de- fault is style. -V, --version Print version information and exit. -W NUM, --wiki-link-count=NUM For TTY output, show NUM wiki links to more information about mentioned warnings. Set to 0 to disable them entirely. -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 fol- lowing any file the script may source. This option may also be enabled using external-sources=true in .shellcheckrc. This flag takes precedence. FILES... One or more script files to check, or "-" for standard input. FORMATS tty Plain text, human readable output. This is the default. gcc GCC compatible output. Useful for editors that support compil- ing 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> diff Auto-fixes in unified diff format. Can be piped to git apply or patch -p1 to automatically apply fixes. --- a/test.sh +++ b/test.sh @@ -2,6 +2,6 @@ ## Example of a broken script. for f in $(ls *.m3u) do - grep -qi hq.*mp3 $f \ + grep -qi hq.*mp3 "$f" \ && echo -e 'Playlist $f contains a HQ file in mp3 format' done json1 Json is a popular serialization format that is more suitable for web applications. ShellCheck's json is compact and contains only the bare minimum. Tabs are counted as 1 character. { comments: [ { "file": "filename", "line": lineNumber, "column": columnNumber, "level": "severitylevel", "code": errorCode, "message": "warning message" }, ... ] } json This is a legacy version of the json1 format. It's a raw array of comments, and all offsets have a tab stop of 8. quiet Suppress all normal output. Exit with zero if no issues are found, otherwise exit with one. Stops processing after the first issue. DIRECTIVES ShellCheck directives can be specified as comments in the shell script. If they appear before the first command, they are considered file-wide. Otherwise, they apply to the immediately following command or block: # shellcheck key=value key=value command-or-structure For example, to suppress SC2035 about using ./*.jpg: # shellcheck disable=SC2035 echo "Files: " *.jpg To tell ShellCheck where to look for an otherwise dynamically deter- mined file: # shellcheck source=./lib.sh source "$(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. A range can be be specified with a dash, e.g. dis- able=SC3000-SC4000 to exclude 3xxx. All warnings can be dis- abled with disable=all. enable Enable an optional check by name, as listed with --list-op- tional. Only file-wide enable directives are considered. extended-analysis Set to true/false to enable/disable dataflow analysis. Specify- ing # shellcheck extended-analysis=false in particularly large (2000+ line) auto-generated scripts will reduce ShellCheck's re- source usage at the expense of certain checks. Extended analy- sis is enabled by default. external-sources Set to true in .shellcheckrc to always allow ShellCheck to open arbitrary files from 'source' statements (the way most tools do). This option defaults to false only due to ShellCheck's origin as a remote service for checking untrusted scripts. It can safely be enabled for normal development. 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. source-path Add a directory to the search path for source/. statements (by default, only ShellCheck's working directory is included). Ab- solute paths will also be rooted in these paths. The special path SCRIPTDIR can be used to specify the currently checked script's directory, as in source-path=SCRIPTDIR or source-path=SCRIPTDIR/../libs. Multiple paths accumulate, and -P takes precedence over them. shell Overrides the shell detected from the shebang. This is useful for files meant to be included (and thus lacking a shebang), or possibly as a more targeted alternative to 'disable=SC2039'. RC FILES Unless --norc is used, ShellCheck will look for a file .shellcheckrc or shellcheckrc in the script's directory and each parent directory. If found, it will read key=value pairs from it and treat them as file-wide directives. Here is an example .shellcheckrc: # Look for 'source'd files relative to the checked script, # and also look for absolute paths in /mnt/chroot source-path=SCRIPTDIR source-path=/mnt/chroot # Since 0.9.0, values can be quoted with '' or "" to allow spaces source-path="My Documents/scripts" # Allow opening any 'source'd file, even if not specified as input external-sources=true # Turn on warnings for unquoted variables with safe values enable=quote-safe-variables # Turn on warnings for unassigned uppercase variables enable=check-unassigned-uppercase # Allow [ ! -z foo ] instead of suggesting -n disable=SC2236 If no .shellcheckrc is found in any of the parent directories, ShellCheck will look in ~/.shellcheckrc followed by the XDG config di- rectory (usually ~/.config/shellcheckrc) on Unix, or %APP- DATA%/shellcheckrc on Windows. Only the first file found will be used. Note for Snap users: the Snap sandbox disallows access to hidden files. Use shellcheckrc without the dot instead. Note for Docker users: ShellCheck will only be able to look for files that are mounted in the container, so ~/.shellcheckrc will not be read. 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 following 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. KNOWN INCOMPATIBILITIES (If nothing in this section makes sense, you are unlikely to be af- fected by it) To avoid confusing and misguided suggestions, ShellCheck requires func- tion bodies to be either { brace groups; } or ( subshells ), and func- tion names containing []*=! are only recognized after a function key- word. The following unconventional function definitions are identical in Bash, but ShellCheck only recognizes the latter. [x!=y] () [[ $1 ]] function [x!=y] () { [[ $1 ]]; } Shells without the function keyword do not allow these characters in function names to begin with. Function names containing {} are not supported at all. Further, if ShellCheck sees [x!=y] it will assume this is an invalid comparison. To invoke the above function, quote the command as in '[x!=y]', or to retain the same globbing behavior, use command [x!=y]. ShellCheck imposes additional restrictions on the [ command to help di- agnose common invalid uses. While [ $x= 1 ] is defined in POSIX, ShellCheck will assume it was intended as the much more likely compari- son [ "$x" = 1 ] and fail accordingly. For unconventional or dynamic uses of the [ command, use test or \[ instead. REPORTING BUGS Bugs and issues can be reported on GitHub: https://github.com/koalaman/shellcheck/issues AUTHORS ShellCheck is developed and maintained by Vidar Holen, with assistance from a long list of wonderful contributors. COPYRIGHT Copyright 2012-2024, Vidar Holen and contributors. Licensed under the GNU General Public License version 3 or later, see https://gnu.org/li- censes/gpl.html SEE ALSO sh(1) bash(1) Shell script analysis tool SHELLCHECK(1)
NAME | SYNOPSIS | DESCRIPTION | OPTIONS | FORMATS | DIRECTIVES | RC FILES | ENVIRONMENT VARIABLES | RETURN VALUES | LOCALE | KNOWN INCOMPATIBILITIES | REPORTING BUGS | AUTHORS | COPYRIGHT | SEE ALSO
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