man.sh: revert trapping SIGPIPE

[concussious]

You teach me a lot with fun puzzles. That really adds a lot to my quality of life. Thanks yet again @emaste!

[concussious]

Cc @wosch @jillest

[emaste]

Confirm this addresses the issue I reported in PR279542

[concussious]

There are other ways to solve this problem (you could trap 'exit 0' SIGPIPE), but I don't understand the use case for them.

[emaste]

Yeah, I'm not sure either -- I'll defer to @wosch for comment.

[concussious]

Confirm that this doesn't reintroduce core dumping on % man 7 salt, which is half a million lines(!), (py311-salt on 15-current) as described in PR223516.

[jillest]

Yes, the main purpose of the default action of SIGPIPE appears to be to terminate processes writing output that is no longer useful, without generating error messages.

Together with set -o pipefail this can still cause non-zero exit statuses, but I don't think this is an issue in this script.

[jillest]

There are other ways to solve this problem (you could trap 'exit 0' SIGPIPE), but I don't understand the use case for them.

The script itself does not commonly write to a closed pipe and non-empty trap actions are turned into the default action in child processes, so trap 'exit 0' PIPE has almost the same effect as not doing anything with SIGPIPE. In either case, if SIGPIPE was inherited as ignored, it will stay that way. So I like it better to do nothing with SIGPIPE.

[concussious]

Thanks @jillest!