Revisions to Get exit status of process that's piped to another

Changed (root) # to (user) $. Beside the obvious mistake of running as root (#), the javascript color the lines in grey after a (#), and that looks ugly.

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edited Dec 31, 2015 at 18:24

user79743

There are 3 common ways of doing this:

Pipefail

The first way is to set the pipefail option (ksh, zsh or bash). This is the simplest and what it does is basically set the exit status $? to the exit code of the last program to exit non-zero (or zero if all exited successfully).

#$ false | true; echo $?
0
#$ set -o pipefail
#$ false | true; echo $?
1

$PIPESTATUS

Bash also has an array variable called $PIPESTATUS ($pipestatus in zsh) which contains the exit status of all the programs in the last pipeline.

#$ true | true; echo "${PIPESTATUS[@]}"
0 0
#$ false | true; echo "${PIPESTATUS[@]}"
1 0
#$ false | true; echo "${PIPESTATUS[0]}"
1
#$ true | false; echo "${PIPESTATUS[@]}"
0 1

You can use the 3rd command example to get the specific value in the pipeline that you need.

Separate executions

This is the most unwieldy of the solutions. Run each command separately and capture the status

#$ OUTPUT="$(echo foo)"
#$ STATUS_ECHO="$?"
#$ printf '%s' "$OUTPUT" | grep -iq "bar"
#$ STATUS_GREP="$?"
#$ echo "$STATUS_ECHO $STATUS_GREP"
0 1

There are 3 common ways of doing this:

Pipefail

The first way is to set the pipefail option (ksh, zsh or bash). This is the simplest and what it does is basically set the exit status $? to the exit code of the last program to exit non-zero (or zero if all exited successfully).

# false | true; echo $?
0
# set -o pipefail
# false | true; echo $?
1

$PIPESTATUS

Bash also has an array variable called $PIPESTATUS ($pipestatus in zsh) which contains the exit status of all the programs in the last pipeline.

# true | true; echo "${PIPESTATUS[@]}"
0 0
# false | true; echo "${PIPESTATUS[@]}"
1 0
# false | true; echo "${PIPESTATUS[0]}"
1
# true | false; echo "${PIPESTATUS[@]}"
0 1

You can use the 3rd command example to get the specific value in the pipeline that you need.

Separate executions

This is the most unwieldy of the solutions. Run each command separately and capture the status

# OUTPUT="$(echo foo)"
# STATUS_ECHO="$?"
# printf '%s' "$OUTPUT" | grep -iq "bar"
# STATUS_GREP="$?"
# echo "$STATUS_ECHO $STATUS_GREP"
0 1

There are 3 common ways of doing this:

Pipefail

The first way is to set the pipefail option (ksh, zsh or bash). This is the simplest and what it does is basically set the exit status $? to the exit code of the last program to exit non-zero (or zero if all exited successfully).

$ false | true; echo $?
0
$ set -o pipefail
$ false | true; echo $?
1

$PIPESTATUS

Bash also has an array variable called $PIPESTATUS ($pipestatus in zsh) which contains the exit status of all the programs in the last pipeline.

$ true | true; echo "${PIPESTATUS[@]}"
0 0
$ false | true; echo "${PIPESTATUS[@]}"
1 0
$ false | true; echo "${PIPESTATUS[0]}"
1
$ true | false; echo "${PIPESTATUS[@]}"
0 1

You can use the 3rd command example to get the specific value in the pipeline that you need.

Separate executions

This is the most unwieldy of the solutions. Run each command separately and capture the status

$ OUTPUT="$(echo foo)"
$ STATUS_ECHO="$?"
$ printf '%s' "$OUTPUT" | grep -iq "bar"
$ STATUS_GREP="$?"
$ echo "$STATUS_ECHO $STATUS_GREP"
0 1

PIPESTATUS was added in bash2.0 decades ago.

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edited Jul 29, 2014 at 13:40

Stéphane Chazelas

584.6k
96
1.1k
1.7k

There are 3 common ways of doing this:

Pipefail

The first way is to set the pipefail option (ksh, zsh or bash). This is the simplest and what it does is basically set the exit status $? to the exit code of the last program to exit non-zero (or zero if all exited successfully).

# false | true; echo $?
0
# set -o pipefail
# false | true; echo $?
1

$PIPESTATUS

Bash also has aan array variable called $PIPESTATUS ($pipestatus in zsh) which contains the exit status of all the programs in the last commandpipeline.

# true | true; echo "${PIPESTATUS[@]}"
0 0
# false | true; echo "${PIPESTATUS[@]}"
1 0
# false | true; echo "${PIPESTATUS[0]}"
1
# true | false; echo "${PIPESTATUS[@]}"
0 1

You can use the 3rd command example to get the specific value in the pipeline that you need.

This solution might not be available though. I think $PIPESTATUS might have been added in a fairly recent version of bash, and your OS may not have it.

Separate executions

This is the most unwieldy of the solutions. Run each command separately and capture the status

# OUTPUT="$(echo foo)"
# STATUS_ECHO="$?"
# printf '%s' "$OUTPUT" | grep -iq "bar"
# STATUS_GREP="$?"
# echo "$STATUS_ECHO $STATUS_GREP"
0 1

There are 3 common ways of doing this:

Pipefail

The first way is to set the pipefail option. This is the simplest and what it does is basically set the exit status $? to the exit code of the last program to exit non-zero (or zero if all exited successfully).

# false | true; echo $?
0
# set -o pipefail
# false | true; echo $?
1

$PIPESTATUS

Bash also has a variable called $PIPESTATUS which contains the exit status of all the programs in the last command.

# true | true; echo "${PIPESTATUS[@]}"
0 0
# false | true; echo "${PIPESTATUS[@]}"
1 0
# false | true; echo "${PIPESTATUS[0]}"
1
# true | false; echo "${PIPESTATUS[@]}"
0 1

You can use the 3rd command example to get the specific value in the pipeline that you need.

This solution might not be available though. I think $PIPESTATUS might have been added in a fairly recent version of bash, and your OS may not have it.

Separate executions

This is the most unwieldy of the solutions. Run each command separately and capture the status

# OUTPUT="$(echo foo)"
# STATUS_ECHO="$?"
# printf '%s' "$OUTPUT" | grep -iq "bar"
# STATUS_GREP="$?"
# echo "$STATUS_ECHO $STATUS_GREP"
0 1

There are 3 common ways of doing this:

Pipefail

The first way is to set the pipefail option (ksh, zsh or bash). This is the simplest and what it does is basically set the exit status $? to the exit code of the last program to exit non-zero (or zero if all exited successfully).

# false | true; echo $?
0
# set -o pipefail
# false | true; echo $?
1

$PIPESTATUS

Bash also has an array variable called $PIPESTATUS ($pipestatus in zsh) which contains the exit status of all the programs in the last pipeline.

# true | true; echo "${PIPESTATUS[@]}"
0 0
# false | true; echo "${PIPESTATUS[@]}"
1 0
# false | true; echo "${PIPESTATUS[0]}"
1
# true | false; echo "${PIPESTATUS[@]}"
0 1

You can use the 3rd command example to get the specific value in the pipeline that you need.

Separate executions

This is the most unwieldy of the solutions. Run each command separately and capture the status

# OUTPUT="$(echo foo)"
# STATUS_ECHO="$?"
# printf '%s' "$OUTPUT" | grep -iq "bar"
# STATUS_GREP="$?"
# echo "$STATUS_ECHO $STATUS_GREP"
0 1

Update to make sense after question merge

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edited Feb 8, 2014 at 9:32

phemmer

73.9k
21
199
231

There are 3 common ways of doing this. However your current setup should work. The reason here being that the grep won't match anything if the command fails, so grep will return with status 1 (unless the program always shows that text no matter what).:

Pipefail

The first way is to set the pipefail option. This is the simplest and what it does is basically set the exit status $? to the exit code of the last program to exit non-zero (or zero if all exited successfully).

# false | true; echo $?
0
# set -o pipefail
# false | true; echo $?
1

$PIPESTATUS

Bash also has a variable called $PIPESTATUS which contains the exit status of all the programs in the last command.

# true | true; echo "${PIPESTATUS[@]}"
0 0
# false | true; echo "${PIPESTATUS[@]}"
1 0
# false | true; echo "${PIPESTATUS[0]}"
1
# true | false; echo "${PIPESTATUS[@]}"
0 1

You can use the 3rd command example to get the specific value in the pipeline that you need.

This solution might not be available though. I think $PIPESTATUS might have been added in a fairly recent version of bash, and your OS may not have it.

Separate executions

This is the most unwieldy of the solutions. Run each command separately and capture the status

# OUTPUT="$(haconfecho -makerwfoo)"
# STATUS_HACONF="$STATUS_ECHO="$?"
# printf '%s' "$OUTPUT" | grep -iq "Cluster"bar"
# alreadySTATUS_GREP="$?"
# writable"echo "$STATUS_ECHO $STATUS_GREP"
0 1

There are 3 ways of doing this. However your current setup should work. The reason here being that the grep won't match anything if the command fails, so grep will return with status 1 (unless the program always shows that text no matter what).

Pipefail

The first way is to set the pipefail option. This is the simplest and what it does is basically set the exit status $? to the exit code of the last program to exit non-zero (or zero if all exited successfully).

# false | true; echo $?
0
# set -o pipefail
# false | true; echo $?
1

$PIPESTATUS

Bash also has a variable called $PIPESTATUS which contains the exit status of all the programs in the last command.

# true | true; echo "${PIPESTATUS[@]}"
0 0
# false | true; echo "${PIPESTATUS[@]}"
1 0
# false | true; echo "${PIPESTATUS[0]}"
1
# true | false; echo "${PIPESTATUS[@]}"
0 1

You can use the 3rd command example to get the specific value in the pipeline that you need.

This solution might not be available though. I think $PIPESTATUS might have been added in a fairly recent version of bash, and your OS may not have it.

Separate executions

This is the most unwieldy of the solutions. Run each command separately and capture the status

# OUTPUT="$(haconf -makerw)"
# STATUS_HACONF="$?"
# printf '%s' "$OUTPUT" | grep -iq "Cluster already writable"

There are 3 common ways of doing this:

Pipefail

The first way is to set the pipefail option. This is the simplest and what it does is basically set the exit status $? to the exit code of the last program to exit non-zero (or zero if all exited successfully).

# false | true; echo $?
0
# set -o pipefail
# false | true; echo $?
1

$PIPESTATUS

Bash also has a variable called $PIPESTATUS which contains the exit status of all the programs in the last command.

# true | true; echo "${PIPESTATUS[@]}"
0 0
# false | true; echo "${PIPESTATUS[@]}"
1 0
# false | true; echo "${PIPESTATUS[0]}"
1
# true | false; echo "${PIPESTATUS[@]}"
0 1

You can use the 3rd command example to get the specific value in the pipeline that you need.

This solution might not be available though. I think $PIPESTATUS might have been added in a fairly recent version of bash, and your OS may not have it.

Separate executions

This is the most unwieldy of the solutions. Run each command separately and capture the status

# OUTPUT="$(echo foo)"
# STATUS_ECHO="$?"
# printf '%s' "$OUTPUT" | grep -iq "bar"
# STATUS_GREP="$?"
# echo "$STATUS_ECHO $STATUS_GREP"
0 1

Post Merged (destination) from unix.stackexchange.com/questions/73170/…

occurred May 17, 2013 at 14:34

Source Link

answered Apr 21, 2013 at 13:56

phemmer

73.9k
21
199
231

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Pipefail

$PIPESTATUS

Separate executions

Pipefail

$PIPESTATUS

Separate executions

Pipefail

$PIPESTATUS

Separate executions

Pipefail

$PIPESTATUS

Separate executions

Pipefail

$PIPESTATUS

Separate executions

Pipefail

$PIPESTATUS

Separate executions

Pipefail

$PIPESTATUS

Separate executions

Pipefail

$PIPESTATUS

Separate executions

Pipefail

$PIPESTATUS

Separate executions