5 SC2312

wileyhy edited this page 2024-10-05 21:44:55 -07:00

Table of Contents

• Consider invoking this command separately to avoid masking its return value (or use '|| true' to ignore).
• Problematic code:
• Correct code:
• Correct code: (with correction)
• Rationale:
• Exceptions:
• Related resources:

Consider invoking this command separately to avoid masking its return value (or use '|| true' to ignore).

This is an optional suggestion enabled with shellcheck -o check-extra-masked-returns or enable=check-extra-masked-returns in a # shellcheck directive or .shellcheckrc.

Problematic code:

set -e
cd "$(get_chroot_dir)/etc"
tar xf "${config}"

Correct code:

set -e
dir="$(get_chroot_dir)"
cd "${dir}/etc"
tar xf "${config}"

Correct code: (with correction)

set -e
dir="$(get_chroot_dir)"
[[ -d "${dir}" ]] || exit 1
cd "${dir}/etc"
tar xf "${config}"

Rationale:

In the problematic example, the exit code for get_chroot_dir is ignored because it is used in a command substitution in the argument of another command.

If the command shows error: Can't determine chroot and exits with failure without outputting a directory, then the command being run will be cd "/etc" and the script will proceed to overwrite the host system's configuration.

By assigning it to a variable first, the exit code of the command will propagate into the exit code of the assignment, so that it can be checked explicitly with if or implicitly with set -e.

Exceptions:

If you don't care about the command's exit status, or already handle it through a side channel like <(cmd; echo $? > status), then you can either ignore the suggestion with a directive, or use || true (or || :) to suppress it.

Related resources:

https://mywiki.wooledge.org/BashPitfalls#cmd1_.26.26_cmd2_.7C.7C_cmd3

• Help by adding links to BashFAQ, StackOverflow, man pages, POSIX, etc!

ShellCheck

• Installation

  • CentOS6
  • More Installation Guides

• Usage

  • Directive
  • Ignore

• Integrating and extending

  • Misc. contributions
  • Azure Pipelines
  • Buildkite
  • CircleCI
  • DevGuide
  • Integration
  • JUnit
  • Phabricator
  • TravisCI
  • GitLab CI
  • Drone
  • GitHub Actions

• Severity

• Template

Each individual ShellCheck warning has its own wiki page like SC1000. Use GitHub Wiki's "Pages" feature above to find a specific one, or see Checks.