On 2/17/19 8:20 PM, Pádraig Brady wrote: > On 15/02/19 07:20, Eric Blake wrote: >> Except that POSIX has the nasty requirement that sh started with an >> inherited ignored SIGPIPE must silently ignore all attempts from within >> the shell to restore SIGPIPE handling to child processes of the shell: >> >> $ (trap '' PIPE; bash -c 'trap - PIPE; \ >> seq 9999 | sort -n | sed 5q | wc -l') >> 5 >> sort: write failed: 'standard output': Broken pipe >> sort: write error > >> You HAVE to use some other intermediate program if you want to override >> an inherited ignored SIGPIPE in sh into an inherited default-behavior >> SIGPIPE in sort. > > Should we also propose to POSIX to allow trap to specify default?
That's what "trap - PIPE" is already supposed to do, except that POSIX has the odd requirement that a signal that was inherited ignored cannot be reset to default. > Maybe `trap 0 PIPE` or similar? Alas, bash has already defined that to mean the same as 'trap - EXIT PIPE'. -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org
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