On Thu, 17 Feb 2022 19:05:45 -0800 Paul Eggert <egg...@cs.ucla.edu> wrote: > On 2/16/22 23:57, Ulrich Eckhardt wrote: > > In order to fix that bug in the above script, you currently have to > > replace `grep ...` with `grep ... || [ $? = 1 ]`, which is not > > really readable. > > Actually, appending something "|| test $? -eq 1" looks readable to > me; plus, it already works and is portable to non-GNU systems which > is a plus. Furthermore, it also works with other programs that also > return 0,1,>1 depending on success,failure,error (e.g., 'cmp', > 'diff', 'sort'), and it doesn't sound like much of a win to add > unportable --pipe options to every such program.
I wasn't aware of those, but I'd say they are candidates as well! I receive the result of the grep operation on stdout, so I don't want any categorization via the exit code. I'm also still not 100% sure on the idea, which is why I'm putting this up for discussion. I think my main two arguments are - Shell scripting uses nonzero exit codes to signal errors by default. grep is an exception here (as are cmp, diff and sort as I understand you), and for a reason, but it doesn't provide an option to use default behaviour. - Also, just arguing in the context of grep, there is an option to "just tell me if there was a match, don't give me the results" and I want a complementary "just give me the results, don't tell me if there was a match". > And it's not just commands like 'cmp' and 'grep'. The following > causes Bash to exit on GNU/Linux: > > set -eo pipefail > cat /usr/share/dict/american-english | grep -l '^' > > This is not because of anything 'grep' does, as 'grep' exits with > status zero. It's because 'cat' exits with nonzero status. Surely we > shouldn't add a --pipe option to 'cat' too. It doesn't do that here, I wonder why you are seeing an error there? Also, if it did, that would signal an actual error, which is behaviour I'm completely fine with. That said, I received feedback from another side (busybox) which is strongly against a `-p` alias, because BSD grep already uses that one. Thank you for your input, Paul, I'm enjoying this exchange! Uli
