2 SC2188

Joachim Ansorg edited this page 2021-11-12 19:45:55 +01:00

Table of Contents

• This redirection doesn't have a command. Move to its command (or use true as no-op).
• Problematic code:
• Correct code:
• Rationale:
• Exceptions:

This redirection doesn't have a command. Move to its command (or use true as no-op).

Problematic code:

{ 
  echo "Report for $(date +%F)"
  uptime
  df -h
}
  > report.txt

Correct code:

{ 
  echo "Report for $(date +%F)"
  uptime
  df -h
} > report.txt

Rationale:

ShellCheck found a redirection that doesn't actually redirect from/to anything.

This could indicate a bug, such as in the problematic code where an additional linefeed causes report.txt to be truncated instead of containing report output, or in foo & > bar, where either foo &> bar or foo > bar & was intended.

However, it could also be intentionally used to truncate a file or check that it's readable. You can make this more explicit for both ShellCheck and human readers by using true or : as a dummy command, e.g. true > file or : > file.

Exceptions:

There are no semantic problems with using > foo over true > foo, so if you don't see this as a potential source of bugs or confusion, you can ignore it.

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