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In bash script I'm developing I'm trying to execute command and capture in variable(s):

  • stdout
  • stderr
  • status code

how to achieve that? The command is tar, if it is of any significance.

I tried the most standard approach:

TAROUTPUT=$(tar -cf arch.tar /path/to/dir)

Based on some work I did (I haven't actually produced tar failure) I get only stdout from this, stderr is not stored to variable. The perfect solution has TAROUTPUT (with both stdout&stderr) and TARSTATUS variables.

Thanks in advance.

2
TAROUTPUT=$(tar -cf arch.tar /path/to/dir 2>&1)
this_is_the_tar_exit_code=$?
  • Yes, working, thanks. Will accept answer in a minute – Miloš Đakonović May 20 '18 at 12:15
  • @HaukeLaging: This puts stdout and stderr together into TAROUTPUT. If I understood the OP correctly, he wants to collect stdout and stderr into different variables. – user1934428 May 21 '18 at 6:24
  • 1
    @user1934428 That's not how I understand "TAROUTPUT (with both stdout&stderr)" – Hauke Laging May 21 '18 at 8:48
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If you want to separate stdout from stderr:

craft@engine:~$ tar -cf arch.tar /path/to/dir 1>/tmp/tar_stdout 2>/tmp/tar_stderr; RETCODE=$( echo ${?} );
craft@engine:~$ stdout_var=$( cat /tmp/tar_stdout )
craft@engine:~$ stderr_var=$( cat /tmp/tar_stderr )
craft@engine:~$ echo -e "STDOUT : ${stdout_var}\nSTDERR : ${stderr_var}\nCommand Status: ${RETCODE}"
  • 1>/tmp/tar_stdout : save the stdout output to a temp file.
  • 2>/tmp/tar_stderr : save stderr output to a file.
  • Return code of the command (exit status) is saved into the ${?} variable.

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