7 SC2043

Vidar Holen edited this page 2023-12-10 20:20:06 -08:00

Table of Contents

• This loop will only ever run once for a constant value. Did you perhaps mean to loop over dir/*, $var or $(cmd)?
• Problematic code:
• Correct code:
• Rationale:
• Exceptions

This loop will only ever run once for a constant value. Did you perhaps mean to loop over dir/*, $var or $(cmd)?

Problematic code:

for var in value
do
  echo "$var"
done

Correct code:

Correct code depends on what you want to do.

To iterate over files in a directory, instead of for var in /my/dir use:

for var in /my/dir/* ; do echo "$var"; done

To iterate over lines in a file or command output, use a while read loop instead:

mycommand | while IFS= read -r line; do echo "$line"; done

To iterate over words written to a command or function's stdout, instead of for var in myfunction, use

for var in $(myfunction); do echo "$var"; done

To iterate over words in a variable, instead of for var in myvariable, use

for var in $myvariable; do echo "$var"; done

Rationale:

ShellCheck has detected that your for loop iterates over a single, constant value. This is most likely a bug in your code, caused by you not expanding the value in the way you want.

You should make sure that whatever you loop over will expand into multiple words.

Exceptions

If you stylistically choose to use for loops with a single element, e.g. to align with other code or to set up for future extensibility (for target in x86_64; do ..), you can ignore this warning.

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