Build Status

ShellCheck - A shell script static analysis tool

ShellCheck is a GPLv3 tool that gives warnings and suggestions for bash/sh shell scripts:

Screenshot of a terminal showing problematic shell script lines highlighted

The goals of ShellCheck are

  • To point out and clarify typical beginner’s syntax issues that cause a shell to give cryptic error messages.

  • To point out and clarify typical intermediate level semantic problems that cause a shell to behave strangely and counter-intuitively.

  • To point out subtle caveats, corner cases and pitfalls that may cause an advanced user’s otherwise working script to fail under future circumstances.

See the gallery of bad code for examples of what ShellCheck can help you identify!

Table of Contents

How to use

There are a number of ways to use ShellCheck!

On the web

Paste a shell script on for instant feedback. is always synchronized to the latest git commit, and is the easiest way to give ShellCheck a go. Tell your friends!

From your terminal

Run shellcheck yourscript in your terminal for instant output, as seen above.

In your editor

You can see ShellCheck suggestions directly in a variety of editors.

Screenshot of Vim showing inlined shellcheck feedback.

Screenshot of emacs showing inlined shellcheck feedback.

In your build or test suites

While ShellCheck is mostly intended for interactive use, it can easily be added to builds or test suites. It makes canonical use of exit codes, so you can just add a shellcheck command as part of the process.

For example, in a Makefile:

    # Fail if any of these files have warnings
    shellcheck myscripts/*.sh

or in a Travis CI .travis.yml file:

  # Fail if any of these files have warnings
  - shellcheck myscripts/*.sh

Services and platforms that have ShellCheck pre-installed and ready to use:

Most other services, including GitLab, let you install ShellCheck yourself, either through the system’s package manager (see Installing), or by downloading and unpacking a binary release.

It’s a good idea to manually install a specific ShellCheck version regardless. This avoids any surprise build breaks when a new version with new warnings is published.

For customized filtering or reporting, ShellCheck can output simple JSON, CheckStyle compatible XML, GCC compatible warnings as well as human readable text (with or without ANSI colors). See the Integration wiki page for more documentation.


The easiest way to install ShellCheck locally is through your package manager.

On systems with Cabal (installs to ~/.cabal/bin):

cabal update
cabal install ShellCheck

On systems with Stack (installs to ~/.local/bin):

stack update
stack install ShellCheck

On Debian based distros:

sudo apt install shellcheck

On Arch Linux based distros:

pacman -S shellcheck

or get the dependency free shellcheck-bin from the AUR.

On Gentoo based distros:

emerge --ask shellcheck

On EPEL based distros:

sudo yum -y install epel-release
sudo yum install ShellCheck

On Fedora based distros:

dnf install ShellCheck

On FreeBSD:

pkg install hs-ShellCheck

On macOS (OS X) with Homebrew:

brew install shellcheck

Or with MacPorts:

sudo port install shellcheck

On OpenBSD:

pkg_add shellcheck

On openSUSE

zypper in ShellCheck

Or use OneClickInstall -

On Solus:

eopkg install shellcheck

On Windows (via chocolatey):

C:\> choco install shellcheck

Or Windows (via scoop):

C:\> scoop install shellcheck

From conda-forge:

conda install -c conda-forge shellcheck

From Snap Store:

snap install --channel=edge shellcheck

From Docker Hub:

docker run --rm -v "$PWD:/mnt" koalaman/shellcheck:stable myscript
# Or :v0.4.7 for that version, or :latest for daily builds

or use koalaman/shellcheck-alpine if you want a larger Alpine Linux based image to extend. It works exactly like a regular Alpine image, but has shellcheck preinstalled.

Using the nix package manager:

nix-env -iA nixpkgs.shellcheck

Alternatively, you can download pre-compiled binaries for the latest release here:

or see the GitHub Releases for other releases (including the latest meta-release for daily git builds).

Distro packages already come with a man page. If you are building from source, it can be installed with:

pandoc -s -f markdown-smart -t man -o shellcheck.1
sudo mv shellcheck.1 /usr/share/man/man1


To run ShellCheck via pre-commit, add the hook to your .pre-commit-config.yaml:

-   repo:
    rev: v0.7.2
    -   id: shellcheck
#       args: ["--severity=warning"]  # Optionally only show errors and warnings

Travis CI

Travis CI has now integrated ShellCheck by default, so you don’t need to manually install it.

If you still want to do so in order to upgrade at your leisure or ensure you’re using the latest release, follow the steps below to install a binary version.

Installing a pre-compiled binary

The pre-compiled binaries come in tar.xz files. To decompress them, make sure xz is installed. On Debian/Ubuntu/Mint, you can apt install xz-utils. On Redhat/Fedora/CentOS, yum -y install xz.

A simple installer may do something like:

scversion="stable" # or "v0.4.7", or "latest"
wget -qO- "${scversion?}/shellcheck-${scversion?}.linux.x86_64.tar.xz" | tar -xJv
cp "shellcheck-${scversion}/shellcheck" /usr/bin/
shellcheck --version

Compiling from source

This section describes how to build ShellCheck from a source directory. ShellCheck is written in Haskell and requires 2GB of RAM to compile.

Installing Cabal

ShellCheck is built and packaged using Cabal. Install the package cabal-install from your system’s package manager (with e.g. apt-get, brew, emerge, yum, or zypper).

On macOS (OS X), you can do a fast install of Cabal using brew, which takes a couple of minutes instead of more than 30 minutes if you try to compile it from source.

$ brew install cabal-install

On MacPorts, the package is instead called hs-cabal-install, while native Windows users should install the latest version of the Haskell platform from

Verify that cabal is installed and update its dependency list with

$ cabal update

Compiling ShellCheck

git clone this repository, and cd to the ShellCheck source directory to build/install:

$ cabal install

Or if you intend to run the tests:

$ cabal install --enable-tests

This will compile ShellCheck and install it to your ~/.cabal/bin directory.

Add this directory to your PATH (for bash, add this to your ~/.bashrc):

export PATH="$HOME/.cabal/bin:$PATH"

Log out and in again, and verify that your PATH is set up correctly:

$ which shellcheck

On native Windows, the PATH should already be set up, but the system may use a legacy codepage. In cmd.exe, powershell.exe and Powershell ISE, make sure to use a TrueType font, not a Raster font, and set the active codepage to UTF-8 (65001) with chcp:

chcp 65001

In Powershell ISE, you may need to additionally update the output encoding:

[Console]::OutputEncoding = [System.Text.Encoding]::UTF8

Running tests

To run the unit test suite:

$ cabal test

Gallery of bad code

So what kind of things does ShellCheck look for? Here is an incomplete list of detected issues.


ShellCheck can recognize several types of incorrect quoting:

echo $1                           # Unquoted variables
find . -name *.ogg                # Unquoted find/grep patterns
rm "~/my file.txt"                # Quoted tilde expansion
v='--verbose="true"'; cmd $v      # Literal quotes in variables
for f in "*.ogg"                  # Incorrectly quoted 'for' loops
touch $@                          # Unquoted $@
echo 'Don't forget to restart!'   # Singlequote closed by apostrophe
echo 'Don\'t try this at home'    # Attempting to escape ' in ''
echo 'Path is $PATH'              # Variables in single quotes
trap "echo Took ${SECONDS}s" 0    # Prematurely expanded trap
unset var[i]                      # Array index treated as glob


ShellCheck can recognize many types of incorrect test statements.

[[ n != 0 ]]                      # Constant test expressions
[[ -e *.mpg ]]                    # Existence checks of globs
[[ $foo==0 ]]                     # Always true due to missing spaces
[[ -n "$foo " ]]                  # Always true due to literals
[[ $foo =~ "fo+" ]]               # Quoted regex in =~
[ foo =~ re ]                     # Unsupported [ ] operators
[ $1 -eq "shellcheck" ]           # Numerical comparison of strings
[ $n && $m ]                      # && in [ .. ]
[ grep -q foo file ]              # Command without $(..)
[[ "$$file" == *.jpg ]]           # Comparisons that can't succeed
(( 1 -lt 2 ))                     # Using test operators in ((..))
[ x ] & [ y ] | [ z ]             # Accidental backgrounding and piping

Frequently misused commands

ShellCheck can recognize instances where commands are used incorrectly:

grep '*foo*' file                 # Globs in regex contexts
find . -exec foo {} && bar {} \;  # Prematurely terminated find -exec
sudo echo 'Var=42' > /etc/profile # Redirecting sudo
time --format=%s sleep 10         # Passing time(1) flags to time builtin
while read h; do ssh "$h" uptime  # Commands eating while loop input
alias archive='mv $1 /backup'     # Defining aliases with arguments
tr -cd '[a-zA-Z0-9]'              # [] around ranges in tr
exec foo; echo "Done!"            # Misused 'exec'
find -name \*.bak -o -name \*~ -delete  # Implicit precedence in find
# find . -exec foo > bar \;       # Redirections in find
f() { whoami; }; sudo f           # External use of internal functions

Common beginner’s mistakes

ShellCheck recognizes many common beginner’s syntax errors:

var = 42                          # Spaces around = in assignments
$foo=42                           # $ in assignments
for $var in *; do ...             # $ in for loop variables
var$n="Hello"                     # Wrong indirect assignment
echo ${var$n}                     # Wrong indirect reference
var=(1, 2, 3)                     # Comma separated arrays
array=( [index] = value )         # Incorrect index initialization
echo $var[14]                     # Missing {} in array references
echo "Argument 10 is $10"         # Positional parameter misreference
if $(myfunction); then ..; fi     # Wrapping commands in $()
else if othercondition; then ..   # Using 'else if'
f; f() { echo "hello world; }     # Using function before definition
[ false ]                         # 'false' being true
if ( -f file )                    # Using (..) instead of test


ShellCheck can make suggestions to improve style:

[[ -z $(find /tmp | grep mpg) ]]  # Use grep -q instead
a >> log; b >> log; c >> log      # Use a redirection block instead
echo "The time is `date`"         # Use $() instead
cd dir; process *; cd ..;         # Use subshells instead
echo $[1+2]                       # Use standard $((..)) instead of old $[]
echo $(($RANDOM % 6))             # Don't use $ on variables in $((..))
echo "$(date)"                    # Useless use of echo
cat file | grep foo               # Useless use of cat

Data and typing errors

ShellCheck can recognize issues related to data and typing:

args="$@"                         # Assigning arrays to strings
files=(foo bar); echo "$files"    # Referencing arrays as strings
declare -A arr=(foo bar)          # Associative arrays without index
printf "%s\n" "Arguments: $@."    # Concatenating strings and arrays
[[ $# > 2 ]]                      # Comparing numbers as strings
var=World; echo "Hello " var      # Unused lowercase variables
echo "Hello $name"                # Unassigned lowercase variables
cmd | read bar; echo $bar         # Assignments in subshells
cat foo | cp bar                  # Piping to commands that don't read
printf '%s: %s\n' foo             # Mismatches in printf argument count
eval "${array[@]}"                # Lost word boundaries in array eval
for i in "${x[@]}"; do ${x[$i]}   # Using array value as key


ShellCheck can make suggestions for improving the robustness of a script:

rm -rf "$STEAMROOT/"*            # Catastrophic rm
touch ./-l; ls *                 # Globs that could become options
find . -exec sh -c 'a && b {}' \; # Find -exec shell injection
printf "Hello $name"             # Variables in printf format
for f in $(ls *.txt); do         # Iterating over ls output
export MYVAR=$(cmd)              # Masked exit codes
case $version in 2.*) :;; 2.6.*) # Shadowed case branches


ShellCheck will warn when using features not supported by the shebang. For example, if you set the shebang to #!/bin/sh, ShellCheck will warn about portability issues similar to checkbashisms:

echo {1..$n}                     # Works in ksh, but not bash/dash/sh
echo {1..10}                     # Works in ksh and bash, but not dash/sh
echo -n 42                       # Works in ksh, bash and dash, undefined in sh
expr match str regex             # Unportable alias for `expr str : regex`
trap 'exit 42' sigint            # Unportable signal spec
cmd &> file                      # Unportable redirection operator
read foo < /dev/tcp/host/22      # Unportable intercepted files
foo-bar() { ..; }                # Undefined/unsupported function name
[ $UID = 0 ]                     # Variable undefined in dash/sh
local var=value                  # local is undefined in sh
time sleep 1 | sleep 5           # Undefined uses of 'time'


ShellCheck recognizes a menagerie of other issues:

PS1='\e[0;32m\$\e[0m '            # PS1 colors not in \[..\]
PATH="$PATH:~/bin"                # Literal tilde in $PATH
rm “file”                         # Unicode quotes
echo "Hello world"                # Carriage return / DOS line endings
echo hello \                      # Trailing spaces after \
var=42 echo $var                  # Expansion of inlined environment
!# bin/bash -x -e                 # Common shebang errors
echo $((n/180*100))               # Unnecessary loss of precision
ls *[:digit:].txt                 # Bad character class globs
sed 's/foo/bar/' file > file      # Redirecting to input
var2=$var2                        # Variable assigned to itself
[ x$var = xval ]                  # Antiquated x-comparisons
ls() { ls -l "$@"; }              # Infinitely recursive wrapper
alias ls='ls -l'; ls foo          # Alias used before it takes effect
for x; do for x; do               # Nested loop uses same variable
while getopts "a" f; do case $f in "b") # Unhandled getopts flags


At first you’re like “shellcheck is awesome” but then you’re like “wtf are we still using bash”

Alexander Tarasikov, via Twitter

Ignoring issues

Issues can be ignored via environmental variable, command line, individually or globally within a file:

Reporting bugs

Please use the GitHub issue tracker for any bugs or feature suggestions:


Please submit patches to code or documentation as GitHub pull requests! Check out the DevGuide on the ShellCheck Wiki.

Contributions must be licensed under the GNU GPLv3. The contributor retains the copyright.


ShellCheck is licensed under the GNU General Public License, v3. A copy of this license is included in the file LICENSE.

Copyright 2012-2019, Vidar ‘koala_man’ Holen and contributors.

Happy ShellChecking!

Other Resources

  • The wiki has long form descriptions for each warning, e.g. SC2221.
  • ShellCheck does not attempt to enforce any kind of formatting or indenting style, so also check out shfmt!


v0.9.0 - 2022-12-12


  • SC2316: Warn about ‘local readonly foo’ and similar (thanks, patrickxia!)
  • SC2317: Warn about unreachable commands
  • SC2318: Warn about backreferences in ‘declare x=1 y=$x’
  • SC2319/SC2320: Warn when $? refers to echo/printf/[ ]/[[ ]]/test
  • SC2321: Suggest removing $((..)) in array[$((idx))]=val
  • SC2322: Suggest collapsing double parentheses in arithmetic contexts
  • SC2323: Suggest removing wrapping parentheses in a[(x+1)]=val


  • SC2086: Now uses DFA to make more accurate predictions about values
  • SC2086: No longer warns about values declared as integer with declare -i


  • ShellCheck now has a Data Flow Analysis engine to make smarter decisions based on control flow rather than just syntax. Existing checks will gradually start using it, which may cause them to trigger differently (but more accurately).
  • Values in directives/shellcheckrc can now be quoted with ‘’ or “”

v0.8.0 - 2021-11-06


  • disable=all now conveniently disables all warnings
  • external-sources=true directive can be added to .shellcheckrc to make shellcheck behave as if -x was specified.
  • Optional check-extra-masked-returns for pointing out commands with suppressed exit codes (SC2312).
  • Optional require-double-brackets for recommending [[ ]] (SC2292).
  • SC2286-SC2288: Warn when command name ends in a symbol like /.)'"
  • SC2289: Warn when command name contains tabs or linefeeds
  • SC2291: Warn about repeated unquoted spaces between words in echo
  • SC2292: Suggest [[ over [ in Bash/Ksh scripts (optional)
  • SC2293/SC2294: Warn when calling eval with arrays
  • SC2295: Warn about “${x#$y}” treating $y as a pattern when not quoted
  • SC2296-SC2301: Improved warnings for bad parameter expansions
  • SC2302/SC2303: Warn about loops over array values when using them as keys
  • SC2304-SC2306: Warn about unquoted globs in expr arguments
  • SC2307: Warn about insufficient number of arguments to expr
  • SC2308: Suggest other approaches for non-standard expr extensions
  • SC2313: Warn about read with unquoted, array indexed variable


  • SC2102 about repetitions in ranges no longer triggers on [[ -v arr[xx] ]]
  • SC2155 now recognizes typeset and local read-only declare statements
  • SC2181 now tries to avoid triggering for error handling functions
  • SC2290: Warn about misused = in declare & co, which were not caught by SC2270+
  • The flag –color=auto no longer outputs color when TERM is “dumb” or unset


  • SC2048: Warning about $* now also applies to ${array[*]}
  • SC2181 now only triggers on single condition tests like [ $? = 0 ].
  • Quote warnings are now emitted for declaration utilities in sh
  • Leading _ can now be used to suppress warnings about unused variables
  • TTY output now includes warning level in text as well as color


  • SC1004: Literal backslash+linefeed in ‘’ was found to be usually correct

v0.7.2 - 2021-04-19


  • disable directives can now be a range, e.g. disable=SC3000-SC4000
  • SC1143: Warn about line continuations in comments
  • SC2259/SC2260: Warn when redirections override pipes
  • SC2261: Warn about multiple competing redirections
  • SC2262/SC2263: Warn about aliases declared and used in the same parsing unit
  • SC2264: Warn about wrapper functions that blatantly recurse
  • SC2265/SC2266: Warn when using & or | with test statements
  • SC2267: Warn when using xargs -i instead of -I
  • SC2268: Warn about unnecessary x-comparisons like [ x$var = xval ]


  • SC1072/SC1073 now respond to disable annotations, though ignoring parse errors is still purely cosmetic and does not allow ShellCheck to continue.
  • Improved error reporting for trailing tokens after ]/]] and compound commands
  • #!/usr/bin/env -S shell is now handled correctly
  • Here docs with \r are now parsed correctly and give better warnings


  • Assignments are now parsed to spec, without leniency for leading $ or spaces
  • POSIX/dash unsupported feature warnings now have individual SC3xxx codes
  • SC1090: A leading $x/ or $(x)/ is now treated as ./ when locating files
  • SC2154: Variables appearing in -z/-n tests are no longer considered unassigned
  • SC2270-SC2285: Improved warnings about misused =, e.g. ${var}=42

v0.7.1 - 2020-04-04


  • -f diff no longer claims that it found more issues when it didn’t
  • Known empty variables now correctly trigger SC2086
  • ShellCheck should now be compatible with Cabal 3
  • SC2154 and all command-specific checks now trigger for builtins called with builtin


  • SC1136: Warn about unexpected characters after ]/]]
  • SC2254: Suggest quoting expansions in case statements
  • SC2255: Suggest using $((..)) in [ 2*3 -eq 6 ]
  • SC2256: Warn about translated strings that are known variables
  • SC2257: Warn about arithmetic mutation in redirections
  • SC2258: Warn about trailing commas in for loop elements


  • SC2230: ‘command -v’ suggestion is now off by default (-i deprecate-which)
  • SC1081: Keywords are now correctly parsed case sensitively, with a warning

v0.7.0 - 2019-07-28


  • Precompiled binaries for macOS and Linux aarch64
  • Preliminary support for fix suggestions
  • New -f diff unified diff format for auto-fixes
  • Files containing Bats tests can now be checked
  • Directory wide directives can now be placed in a .shellcheckrc
  • Optional checks: Use --list-optional to show a list of tests, Enable with -o flags or enable=name directives
  • Source paths: Use -P dir1:dir2 or a source-path=dir1 directive to specify search paths for sourced files.
  • json1 format like –format=json but treats tabs as single characters
  • Recognize FLAGS variables created by the shflags library.
  • Site-specific changes can now be made in Custom.hs for ease of patching
  • SC2154: Also warn about unassigned uppercase variables (optional)
  • SC2252: Warn about [ $a != x ] || [ $a != y ], similar to SC2055
  • SC2251: Inform about ineffectual ! in front of commands
  • SC2250: Warn about variable references without braces (optional)
  • SC2249: Warn about case with missing default case (optional)
  • SC2248: Warn about unquoted variables without special chars (optional)
  • SC2247: Warn about $”(cmd)” and $”{var}”
  • SC2246: Warn if a shebang’s interpreter ends with /
  • SC2245: Warn that Ksh ignores all but the first glob result in [
  • SC2243/SC2244: Suggest using explicit -n for [ $foo ] (optional)
  • SC1135: Suggest not ending double quotes just to make $ literal


  • If a directive or shebang is not specified, a .bash/.bats/.dash/.ksh extension will be used to infer the shell type when present.
  • Disabling SC2120 on a function now disables SC2119 on call sites


  • SC2183 no longer warns about missing printf args for %()T

v0.6.0 - 2018-12-02


  • Command line option –severity/-S for filtering by minimum severity
  • Command line option –wiki-link-count/-W for showing wiki links
  • SC2152/SC2151: Warn about bad exit values like 1234 and "foo"
  • SC2236/SC2237: Suggest -n/-z instead of ! -z/-n
  • SC2238: Warn when redirecting to a known command name, e.g. ls > rm
  • SC2239: Warn if the shebang is not an absolute path, e.g. #!bin/sh
  • SC2240: Warn when passing additional arguments to dot (.) in sh/dash
  • SC1133: Better diagnostics when starting a line with |/||/&&


  • Most warnings now have useful end positions
  • SC1117 about unknown double-quoted escape sequences has been retired


  • SC2021 no longer triggers for equivalence classes like [=e=]
  • SC2221/SC2222 no longer mistriggers on fall-through case branches
  • SC2081 about glob matches in [ .. ] now also triggers for !=
  • SC2086 no longer warns about spaces in $#
  • SC2164 no longer suggests subshells for cd ..; cmd; cd ..
  • read -a is now correctly considered an array assignment
  • SC2039 no longer warns about LINENO now that it’s POSIX

v0.5.0 - 2018-05-31


  • SC2233/SC2234/SC2235: Suggest removing or replacing (..) around tests
  • SC2232: Warn about invalid arguments to sudo
  • SC2231: Suggest quoting expansions in for loop globs
  • SC2229: Warn about ‘read $var’
  • SC2227: Warn about redirections in the middle of ‘find’ commands
  • SC2224/SC2225/SC2226: Warn when using mv/cp/ln without a destination
  • SC2223: Quote warning specific to : ${var=value}
  • SC1131: Warn when using elseif or elsif
  • SC1128: Warn about blanks/comments before shebang
  • SC1127: Warn about C-style comments


  • Annotations intended for a command’s here documents now work
  • Escaped characters inside groups in =~ regexes now parse
  • Associative arrays are now respected in arithmetic contexts
  • SC1087 about $var[@] now correctly triggers on any index
  • Bad expansions in here documents are no longer ignored
  • FD move operations like {fd}>1- now parse correctly


  • Here docs are now terminated as per spec, rather than by presumed intent
  • SC1073: ‘else if’ is now parsed correctly and not like ‘elif’
  • SC2163: ‘export $name’ can now be silenced with ‘export ${name?}’
  • SC2183: Now warns when printf arg count is not a multiple of format count

v0.4.7 - 2017-12-08


  • Statically linked binaries for Linux and Windows (see!
  • -a flag to also include warnings in sourced files
  • SC2221/SC2222: Warn about overridden case branches
  • SC2220: Warn about unhandled error cases in getopt loops
  • SC2218: Warn when using functions before they’re defined
  • SC2216/SC2217: Warn when piping/redirecting to mv/cp and other non-readers
  • SC2215: Warn about commands starting with leading dash
  • SC2214: Warn about superfluous getopt flags
  • SC2213: Warn about unhandled getopt flags
  • SC2212: Suggest false over [ ]
  • SC2211: Warn when using a glob as a command name
  • SC2210: Warn when redirecting to an integer, e.g. foo 1>2
  • SC2206/SC2207: Suggest alternatives when using word splitting in arrays
  • SC1117: Warn about double quoted, undefined backslash sequences
  • SC1113/SC1114/SC1115: Recognized more malformed shebangs


  • [ -v foo ] no longer warns if foo is undefined
  • SC2037 is now suppressed by quotes, e.g. PAGER="cat" man foo
  • Ksh nested array declarations now parse correctly
  • Parameter Expansion without colons are now recognized, e.g. ${foo+bar}
  • The lastpipe option is now respected with regard to subshell warnings
  • \( is now respected for grouping in [
  • Leading \ is now ignored for commands, to allow alias suppression
  • Comments are now allowed after directives to e.g. explain ‘disable’

v0.4.6 - 2017-03-26


  • SC2204/SC2205: Warn about ( -z foo ) and ( foo -eq bar )
  • SC2200/SC2201: Warn about brace expansion in [/[[
  • SC2198/SC2199: Warn about arrays in [/[[
  • SC2196/SC2197: Warn about deprecated egrep/fgrep
  • SC2195: Warn about unmatchable case branches
  • SC2194: Warn about constant ‘case’ statements
  • SC2193: Warn about [[ file.png == *.mp3 ]] and other unmatchables
  • SC2188/SC2189: Warn about redirections without commands
  • SC2186: Warn about deprecated tempfile
  • SC1109: Warn when finding &amp;/&gt;/&lt; unquoted
  • SC1108: Warn about missing spaces in [ var= foo ]


  • All files are now read as UTF-8 with lenient latin1 fallback, ignoring locale
  • Unicode quotes are no longer considered syntactic quotes
  • ash scripts will now be checked as dash with a warning


  • -c no longer suggested when using grep -o | wc
  • Comments and whitespace are now allowed before filewide directives
  • Here doc delimiters with esoteric quoting like foo"" are now handled
  • SC2095 about ssh in while read loops is now suppressed when using -n
  • %(%Y%M%D)T now recognized as a single formatter in printf checks
  • grep -F now suppresses regex related suggestions
  • Command name checks now recognize busybox applet names

v0.4.5 - 2016-10-21


  • A Docker build (thanks, kpankonen!)
  • SC2185: Suggest explicitly adding path for find
  • SC2184: Warn about unsetting globs (e.g. unset foo[1])
  • SC2183: Warn about printf with more formatters than variables
  • SC2182: Warn about ignored arguments with printf
  • SC2181: Suggest using command directly instead of if [ $? -eq 0 ]
  • SC1106: Warn when using test operators in (( 1 -eq 2 ))


  • Unrecognized directives now causes a warning rather than parse failure.


  • Indices in associative arrays are now parsed correctly
  • Missing shebang warning squashed when specifying with a directive
  • Ksh multidimensional arrays are now supported
  • Variables in substring ${a:x:y} expansions now count as referenced
  • SC1102 now also handles ambiguous $((
  • Using $(seq ..) will no longer suggest quoting
  • SC2148 (missing shebang) is now suppressed when using shell directives
  • [ a '>' b ] is now recognized as being correctly escaped

v0.4.4 - 2016-05-15


  • Haskell Stack support (thanks, Arguggi!)
  • SC2179/SC2178: Warn when assigning/appending strings to arrays
  • SC1102: Warn about ambiguous $(((
  • SC1101: Warn when \ linebreaks have trailing spaces


  • Directives directly after the shebang now apply to the entire file


  • {$i..10} is now flagged similar to {1..$i}

v0.4.3 - 2016-01-13


  • Build now works on GHC 7.6.3 as found on Debian Stable/Ubuntu LTS

v0.4.2 - 2016-01-09


  • First class support for the dash shell
  • The --color flag similar to ls/grep’s (thanks, haguenau!)
  • SC2174: Warn about unexpected behavior of mkdir -pm (thanks, eatnumber1!)
  • SC2172: Warn about non-portable use of signal numbers in trap
  • SC2171: Warn about ]] without leading [[
  • SC2168: Warn about local outside functions


  • Warnings about unchecked cd will no longer trigger with set -e
  • [ a -nt/-ot/-ef b ] no longer warns about being constant
  • Quoted test operators like [ foo "<" bar ] now parse
  • Escaped quotes in backticks now parse correctly

v0.4.1 - 2015-09-05


  • Added missing files to Cabal, fixing the build

v0.4.0 - 2015-09-05


  • Support for following sourced files
  • Support for setting default flags in SHELLCHECK_OPTS
  • An --external-sources flag for following arbitrary sourced files
  • A source directive to override the filename to source
  • SC2166: Suggest using [ p ] && [ q ] over [ p -a q ]
  • SC2165: Warn when nested for loops use the same variable name
  • SC2164: Warn when using cd without checking that it succeeds
  • SC2163: Warn about export $var
  • SC2162: Warn when using read without -r
  • SC2157: Warn about [ "$var " ] and similar never-empty string matches


  • cat -vnE file and similar will no longer flag as UUOC
  • Nested trinary operators in (( )) now parse correctly
  • Ksh ${ ..; } command expansions now parse

v0.3.8 - 2015-06-20


  • ShellCheck’s license has changed from AGPLv3 to GPLv3.


  • SC2156: Warn about injecting filenames in find -exec sh -c "{}" \;


  • Variables and command substitutions in brace expansions are now parsed
  • ANSI colors are now disabled on Windows
  • Empty scripts now parse

v0.3.7 - 2015-04-16


  • Build now works on GHC 7.10
  • Use regex-tdfa over regex-compat since the latter crashes on OS X.

v0.3.6 - 2015-03-28


  • SC2155: Warn about masked return values in export foo=$(exit 1)
  • SC2154: Warn when a lowercase variable is referenced but not assigned
  • SC2152/SC2151: Warn about bad return values like 1234 and "foo"
  • SC2150: Warn about find -exec "shell command" \;


  • coproc is now supported
  • Trinary operator now recognized in ((..))


  • Zsh support has been removed

v0.3.5 - 2014-11-09


  • SC2148: Warn when not including a shebang
  • SC2147: Warn about literal ~ in PATH
  • SC1086: Warn about $ in for loop variables, e.g. for $i in ..
  • SC1084: Warn when the shebang uses !# instead of #!


  • Empty and comment-only backtick expansions now parse
  • Variables used in PS1/PROMPT_COMMAND/trap now count as referenced
  • ShellCheck now skips unreadable files and directories
  • -f gcc on empty files no longer crashes
  • Variables in $”..” are now considered quoted
  • Warnings about expansions in single quotes now include backticks

v0.3.4 - 2014-07-08


  • SC2146: Warn about precedence when combining find -o with actions
  • SC2145: Warn when concatenating arrays and strings


  • Case statements now support ;& and ;;&
  • Indices in array declarations now parse correctly
  • let expressions now parsed as arithmetic expressions
  • Escaping is now respected in here documents


  • Completely drop Makefile in favor of Cabal (thanks rodrigosetti!)

v0.3.3 - 2014-05-29


  • SC2144: Warn when using globs in [/[[
  • SC2143: Suggesting using grep -q over [ "$(.. | grep)" ]
  • SC2142: Warn when referencing positional parameters in aliases
  • SC2141: Warn about suspicious IFS assignments like IFS="\n"
  • SC2140: Warn about bad embedded quotes like echo "var="value""
  • SC2130: Warn when using -eq on strings
  • SC2139: Warn about define time expansions in alias definitions
  • SC2129: Suggest command grouping over a >> log; b >> log; c >> log
  • SC2128: Warn when expanding arrays without an index
  • SC2126: Suggest grep -c over grep|wc
  • SC2123: Warn about accidentally overriding $PATH, e.g. PATH=/my/dir
  • SC1083: Warn about literal {/} outside of quotes
  • SC1082: Warn about UTF-8 BOMs


  • SC2051 no longer triggers for {1,$n}, only {1..$n}
  • Improved detection of single quoted sed variables, e.g. sed '$s///'
  • Stop warning about single quoted variables in PS1 and similar
  • Support for Zsh short form loops, =(..)


  • SC1000 about unescaped lonely $, e.g. grep "^foo$"

v0.3.2 - 2014-03-22


  • SC2121: Warn about trying to set variables, e.g. set var = value
  • SC2120/SC2119: Warn when a function uses $1.. if none are ever passed
  • SC2117: Warn when using su in interactive mode, e.g. su foo; whoami
  • SC2116: Detect useless use of echo, e.g. for i in $(echo $var)
  • SC2115/SC2114: Detect some catastrophic rm -r "$empty/" mistakes
  • SC1081: Warn when capitalizing keywords like While
  • SC1077: Warn when using acute accents instead of backticks


  • Shells are now properly recognized in shebangs containing flags
  • Stop warning about math on decimals in ksh/zsh
  • Stop warning about decimal comparisons with =, e.g. [ $version = 1.2 ]
  • Parsing of |&
  • ${a[x]} not counting as a reference of x
  • (( x[0] )) not counting as a reference of x

v0.3.1 - 2014-02-03


  • The -s flag to specify shell dialect
  • SC2105/SC2104: Warn about break/continue outside loops
  • SC1076: Detect invalid [/[[ arithmetic like [ 1 + 2 = 3 ]
  • SC1075: Suggest using elif over else if


  • Don’t warn when comma separating elements in brace expansions
  • Improved detection of single quoted sed variables, e.g. sed '$d'
  • Parsing of arithmetic for loops using {..} instead of do..done
  • Don’t treat the last pipeline stage as a subshell in ksh/zsh

v0.3.0 - 2014-01-19


  • A man page (thanks Dridi!)
  • GCC compatible error reporting (shellcheck -f gcc)
  • CheckStyle compatible XML error reporting (shellcheck -f checkstyle)
  • Error codes for each warning, e.g. SC1234
  • Allow disabling warnings with # shellcheck disable=SC1234
  • Allow disabling warnings with --exclude
  • SC2103: Suggest using subshells over cd foo; bar; cd ..
  • SC2102: Warn about duplicates in char ranges, e.g. [10-15]
  • SC2101: Warn about named classes not inside a char range, e.g. [:digit:]
  • SC2100/SC2099: Warn about bad math expressions like i=i+5
  • SC2098/SC2097: Warn about foo=bar echo $foo
  • SC2095: Warn when using ssh/ffmpeg in while read loops
  • Better warnings for missing here doc tokens


  • Don’t warn when single quoting variables with ssh/perl/eval
  • ${!var} is now counted as a variable reference


  • Suggestions about using parameter expansion over basename
  • The jsoncheck binary. Use shellcheck -f json instead.

v0.2.0 - 2013-10-27


  • Suggest ./* instead of * when passing globs to commands
  • Suggest pgrep over ps | grep
  • Warn about unicode quotes
  • Warn about assigned but unused variables
  • Inform about client side expansion when using ssh


  • CLI tool now uses exit codes and stderr canonically
  • Parsing of extglobs containing empty patterns
  • Parsing of bash style eval foo=(bar)
  • Parsing of expansions in here documents
  • Parsing of function names containing :+-
  • Don’t warn about find|xargs when using -print0

v0.1.0 - 2013-07-23


  • First release