In Bash, how to capture exit status code from a command nested within a complex statement

Question

I'm relatively new to working with bash. I've inherited this bit of code to run a command via SLURM on an HPC system:

CMD="srun -srunParam1 ... -srunParamN ./scriptToRun.sh -scriptParam1"
exec 5>&1
results=$(eval "${CMD}" | tee - >&5))

That all works just fine.

But, I need to capture the exit status of just eval "${CMD}", and don't know how to do it.

Initially, I put exitStatus=$? after the results=... command; but, I believe that's catching the status of assigning a value to the results variable, and not of eval ${CMD}

The script goes on to process the output that is in $results. I don't really understand why the file descriptor has been opened here (or, how to properly use file descriptors). But, I'll save that for further research/a separate question.

EDIT: I commented out the bits with the file descriptor, and observed that the script still works, but $results does not contain the output from running $CMD - it only contains the post-processing of $CMD.

jhnc · Accepted Answer · 2022-03-18 21:45:22Z

4

Bash has PIPESTATUS:

results=$(eval "${CMD}" | tee - >&5; exit ${PIPESTATUS[0]}) 
exitStatus=$?

Note that in the code above we are examining the exit status of a command that was run inside a subshell ($(...)); it would not work to access PIPESTATUS in the parent.

edited Mar 18, 2022 at 21:45

answered Mar 18, 2022 at 19:08

jhnc

18.8k2 gold badges14 silver badges33 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Fravadona Over a year ago

Tall_Joe Over a year ago

Just what the doctor ordered. I googled a bit to research PIPESTATUS, and came upon: https://www.shellscript.sh/tips/pipestatus/. @Fravadona, your comment is right in line with the way that site describes PIPESTATUS

Philippe · Accepted Answer · 2022-03-18 19:06:56Z

0

One way to get status is to save it in a file :

results=$( { eval "${CMD}"; echo $? > /tmp/cmd_status.txt; } | tee - >&5)) 
# Process /tmp/cmd_status.txt here

answered Mar 18, 2022 at 19:06

Philippe

27.7k4 gold badges28 silver badges45 bronze badges

Collectives™ on Stack Overflow

In Bash, how to capture exit status code from a command nested within a complex statement

2 Answers 2

2 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related