unix shell, getting exit code with piped child

Question

Let's say I do this in a unix shell

$ some-script.sh | grep mytext

$ echo $?

this will give me the exit code of grep

but how can I get the exit code of some-script.sh

EDIT

Assume that the pipe operation is immutable. ie, I can not break it apart and run the two commands seperately

Answer 1

There are multiple solutions, it depends on what you want to do exactly.

The easiest and understandable way would be to send the output to a file, then grep for it after saving the exit code:

tmpfile=$(mktemp)
./some-script.sh > $tmpfile
retval=$?
grep mytext $tmpfile
rm tmpfile

Answer 2

A trick from the comp.unix.shell FAQ (#13) explains how using the pipeline in the Bourne shell should help accomplish what you want:

   You need to use a trick to pass the exit codes to the main
   shell.  You can do it using a pipe(2). Instead of running
   "cmd1", you run "cmd1; echo $?" and make sure $? makes it way
   to the shell.

   exec 3>&1
   eval `
     # now, inside the `...`, fd4 goes to the pipe
     # whose other end is read and passed to eval;
     # fd1 is the normal standard output preserved
     # the line before with exec 3>&1
     exec 4>&1 >&3 3>&- 
     {
       cmd1 4>&-; echo "ec1=$?;" >&4
     } | {
       cmd2 4>&-; echo "ec2=$?;" >&4
     } | cmd3
     echo "ec3=$?;" >&4