How to avoid echo closing FIFO named pipes? - Funny behavior of Unix FIFOs

Question

I want to output some data to a pipe and have the other process do something to the data line by line. Here is a toy example:

mkfifo pipe
cat pipe&
cat &         


        

Answer 1

I enhanced the second version from the Jonathan Leffler's answer to support closing the pipe:

dir=`mktemp -d /tmp/temp.XXX`
keep_pipe_open=$dir/keep_pipe_open
pipe=$dir/pipe

mkfifo $pipe
touch $keep_pipe_open

# Read from pipe:
cat < $pipe &

# Keep the pipe open:
while [ -f $keep_pipe_open ]; do sleep 1; done > $pipe &

# Write to pipe:
for i in {1..10}; do
  echo $i > $pipe
done

# close the pipe:
rm $keep_pipe_open
wait

rm -rf $dir