7 SC2129

John A. Lotoski edited this page 2022-06-22 15:48:52 -05:00

Table of Contents

• Consider using { cmd1; cmd2; } >> file instead of individual redirects.
• Problematic code:
• Correct code:
• Rationale:
• Exceptions:
• Related resources:

Consider using { cmd1; cmd2; } >> file instead of individual redirects.

Problematic code:

echo foo >> file
date >> file
cat stuff  >> file

Correct code:

{
  echo foo
  date
  cat stuff
} >> file

Rationale:

Rather than adding >> something after every single line, you can simply group the relevant commands and redirect the group. So the file has to be opened and closed only once and it means a performance gain.

Exceptions:

This is mainly a stylistic issue, and can freely be ignored.

Note: shell traps which would ordinarily emit output to stdout or stderr on catching their condition will have output swallowed into the redirect when the trap is triggered from within the grouping.

Related resources:

• BashFaq: How can I redirect the output of multiple commands at once?

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.