SC3040

In POSIX sh, set option pipefail is undefined.

Problematic code:

#!/bin/sh
set -o pipefail
if cmd1 | cmd2 | cmd3
then
  echo "Success"
fi

Correct code:

fail="$(mktemp)"
if { cmd1 || echo > "$fail"; } |
   { cmd2 || echo > "$fail"; } |
     cmd3 && [ ! -s "$fail" ]
then
  echo "Success"
fi
rm "$fail"

or switch to a shell that supports pipefail, such as Bash.

Rationale:

ShellCheck found set -o pipefail in a script declare to run with sh or dash. This feature may not be supported on these shells.

As an alternative, each stage in the pipeline such as cmd1 can be rewritten as { cmd1 || echo > file; } which will behave as before but now also write the exit code into file if the command fails.

If the file has been written to when the pipeline is done, it means one of the commands failed. This is demonstrated in the correct example.

This can obviously be extended with e.g. echo "cmd1=$?" >> file if the particular exit codes for particular commands are desired.

Exceptions:

If the script has already inspected the current shell and determined the option is available, you can ignore this message.

Related resources:

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