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> #!/bin/bash -p Why are you using the -p option? > echo $$ > cat /tmp/atf | while read; do echo $$; exit 3; done In both cases the $$ is expanded by the shell before invoking the command. So they get the same pid value, the pid of the parent. I don't know how to output the pid of the subshell. Perhaps someone on the mailing list will have an answer. You can verify that there is a subshell however. echo $$ ; echo foo | sleep 123 8924 ...sleep 123 now running... In another terminal look at the processes running. I used 'ps -efH'. Look for pid 8924. rwp 8924 8923 0 10:10 pts/36 00:00:00 bash rwp 1016 8924 0 10:13 pts/36 00:00:00 sleep 123 Bob Blaine Simpson wrote: > Thanks for taking the time to answer (both), Bob. Inline reply below. > > Bob Proulx wrote: > > Blaine Simpson wrote: > > > >> "exit" doesn't exit the current shell when inside of PIPED read blocks, > >> yet everything works find if the input comes from "redirection". > >> > > > > This is because pipes operate in subshells and the exit applies to the > > subshell. Please see the bash FAQ question E4 for more information. > > > > ftp://ftp.cwru.edu/pub/bash/FAQ > > > > > >> cat /tmp/atf | while read; do exit 3; done # for any text file > >> /tmp/atf > >> Yet the following works > >> cat /tmp/atf | while read; do exit 3; done > >> > > > > Those two are the same. You probably meant to say: > > > > while read; do exit 3; done < /tmp/atf > > > Exactly. Copy and paste error from the file where my notes are. > > No pipeline there and so that is done in the current shell. > > > I thought I had eliminated shelling as the cause because I echo'd $$ in > the body (where "exit 3" is above), and it is the same exact pid as the > root shell. > > I'm attaching the test script. > > Bob > > > #!/bin/bash -p > > echo $$ > cat /tmp/atf | while read; do echo $$; exit 3; done > > # WORKS: > #while read; do exit 3; done < /tmp/atf > > echo "Post in $$"
