SUPUNER(1) General Commands Manual SUPUNER(1)

supunerSUPress stdout / stderr UNless ERror

supuner [-e] [-o file] command [options ...]

supuner executes a command and manipulates its stderr and stdout. By default, it captures both stderr and stdout and only outputs their combined value to stdout if command fails.

The options are as follows:

If -o is specified, then as well as sending output to a file, echo stdout and stderr combined to stdout.
file
Send stdout and stderr to file.

supuner exits with the exit code of command.

Here are examples of the basic styles of use of supuner:

$ supuner ls /bin/sh
$ supuner ls /bin/sh /doesntexist
ls: /doesntexist: such file or directory
/bin/sh
$ supuner -o /tmp/o ls /bin/sh /doesntexist
$ echo $?
1
$ cat /tmp/o
ls: /doesntexist: such file or directory
/bin/sh
$ supuner -e -o /tmp/o ls /bin/sh /doesntexist
ls: /doesntexist: such file or directory
/bin/sh
$ echo $?
1
$ cat /tmp/o
ls: /doesntexist: such file or directory
/bin/sh

Using the fact that supuner exits with the exit code of command, one can use the ‘||’ operator to perform actions on the combined stdout / stderr output, for example:

supuner -o /tmp/o ls /bin/sh /doesntexist >2 /dev/null \
  || mail -s 'Error from ls' somebody@something.com < /tmp/o

supuner was written by Laurence Tratt https://tratt.net/laurie/.

February 17, 2020 OpenBSD 6.6