SC2292 – ShellCheck Wiki

Prefer `[[ ]]` over `[ ]` for tests in Bash/Ksh.

This is an optional suggestion. It must be explicitly enabled with a directive enable=require-double-brackets in a # shellcheck comment or .shellcheckrc

Problematic code:

[ -e /etc/issue ]

Correct code:

[[ -e /etc/issue ]]

Rationale:

ShellCheck has been explicitly asked to warn about uses of [ .. ] in favor of the extended Bash/Ksh test [[ .. ]].

[[ .. ]] suppresses word splitting and globbing, supports a wider variety of tests, and is generally safer and better defined than [ .. ]. For an in-depth list of differences, see the Related Resources.

Exceptions:

This check is not enabled by default, and may have been turned on for your current project by someone who wants it enforced. You can still ignore it with a directive.

This suggestion does not trigger for Sh or Dash scripts, even when explicitly enabled, as these shells don't support [[ .. ]].

BashFAQ 031: What is the difference between test, [ and [[ ?

ShellCheck is a static analysis tool for shell scripts. This page is part of its documentation.