Pipe output and capture exit status in Bash

Question

I want to execute a long running command in Bash, and both capture its exit status, and tee its output.

So I do this:

command | tee out.txt
ST=$?


        

Answer 1

Dumb solution: Connecting them through a named pipe (mkfifo). Then the command can be run second.

 mkfifo pipe
 tee out.txt < pipe &
 command > pipe
 echo $?

Answer 2

There is an internal Bash variable called $PIPESTATUS; it’s an array that holds the exit status of each command in your last foreground pipeline of commands.

<command> | tee out.txt ; test ${PIPESTATUS[0]} -eq 0

Or another alternative which also works with other shells (like zsh) would be to enable pipefail:

set -o pipefail
...

The first option does not work with zsh due to a little bit different syntax.

Answer 3

In Ubuntu and Debian, you can apt-get install moreutils. This contains a utility called mispipe that returns the exit status of the first command in the pipe.