shellcheck - Online in the Cloud

PROGRAM:

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, --version
Print version and exit.

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.

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