On June 9, 2022 3:19:56 AM GMT+02:00, Philippe Meunier <meun...@ccs.neu.edu> wrote: >Hi, > >Try: > >$ mkfifo fifo >$ while true; do /bin/echo aaaa > fifo; echo -n "$? "; done > >then in another shell: > >$ tail -f fifo > >and everything works as expected. Now repeatedly interrupt and restart >this tail(1) command and from time to time you'll see that /bin/echo dies >with status 141 because of a SIGPIPE signal. My guess is that this happens >when /bin/echo opens the FIFO and tail(1) then closes it (when it's >interrupted) before /bin/echo has had the chance to do the write so the >write then gets a SIGPIPE. So far so good. > >Now replace /bin/echo with ksh's builtin echo command: > >$ while true; do echo aaaa > fifo; echo -n "$? "; done > >and again repeatedly start / interrupt / restart the tail(1) command above. >The builtin echo command is faster than /bin/echo so it might take a few >more tries but sooner or later the builtin echo command gets a SIGPIPE and >then ksh itself dies, which is... unexpected. > >I tried with bash and the behavior is the same as with ksh. > >I tried with zsh and I get "echo: write error: broken pipe" and zsh doesn't >die, which is what I would have expected from ksh (and bash).
Why? Is there some reference you can point at which suggests your expectations are valid? Otherwise, trap : PIPE might help you out. /Alexander > >So that looks to me like a bug in ksh (and bash). > >Cheers, > >Philippe > >
