Hello,
I have this script, that I've found to never write "DONE" in my systems, with
bash 4.0, 4.1, 4.2.. until 4.2-p20, my last test.
However, in irc some people told me it prints DONE for them. If I run the
script with
bash under 'strace -f', it also prints DONE.
So there is some kind of race in 'read'. The current program output in my
computer is:
reading
debug:done
If 'read' unblocked by error (SIGCHLD?), it would print reading again. If
'read' unblocked having read nothing, it would print a newline (it does not).
And of course it does not print the 'DONE' either.
Maybe it's me not understanding something? I suspect that 'read' reacts to
EINTR, and tries to read again, with the error of *reopening the pipe*
(<$PIPE), which will make it block forever.
Here the script:
-----------
#!/var/run/current-system/sw/bin/bash
PIPE=/tmp/pipe
rm -f $PIPE
mkfifo $PIPE
function spawn {
"$@"
echo debug:done
echo DONE > $PIPE
}
spawn sleep 1 &
while true; do
echo reading
while read LINE < $PIPE; do
echo $LINE
exit 0
done
done
-----------------
Regards,
Lluís.
