CODEWITHSUNDEEP
bashshell
VeryNiceArgumentException
VeryNiceArgumentException

Reputation: 2066

Bash piped commands and its returns

Is there any way to a piped commands to replicate its previous command exit status?

For example:

#/bin/bash
(...)
function customizedLog() {
   # do something with the piped command output
   exit <returned value from the last piped comand/script (script.sh)>
}

script.sh | customizedLog
echo ${?} # here I wanna show the script exit value
(...)

I know I could simply check the return using ${PIPESTATUS[0]}, but I really want to do this like the customizedLog function wasn't there.

Any thoughts?

Upvotes: 2

Views: 138

Answers (2)

Petr Skocik
Petr Skocik

Reputation: 60067

script.sh | customizedLog

The above will run in two separate processes (or 3, actually -- customizedLog will run in a bash fork as you can verify with something like ps -T --forest). As far as I know, with the UNIX process model, the only process that has access to a process's return information is its parent so there's no way customized log will be able to retrieve it.

So no, unless the previous command is run from a wrapper command that passes the exit status through the pipe (e.g., as the last line):

( command ; echo $? ) | piped_command_that_is_aware_of_such_an_arrangement

Upvotes: 2

Jonathan Leffler
Jonathan Leffler

Reputation: 753990

In bash:

set -o pipefail

This will return the last non-zero exit status in a pipeline, or zero if all commands in the pipeline succeed.

set -o pipefail
script.sh | customizedLog
echo ${?}

Just make sure customizedLog succeeds (return 0), and you should pick up the exit status of script.sh. Test with false | customizedLog and true | customizedLog.

Upvotes: 4

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