Exit bash script if subprocess exits with non-zero code

Question

I have this line in a bash script:

$ node $(node `dirname $0`/foo.js) "$@"

In foo.js, I have

if(x){
process.exit(0);
}
else{
process.exit(1);
}

I want the bash script to abort / error out, if the process defined by

$(node `dirname $0`/foo.js)

exits with a non-zero exit code.

How can I do this?

choroba · Accepted Answer · 2016-11-23 22:04:14Z

2

Update

If you want to capture the exit code of the command substitution, assign the output to a variable. The assignment doesn't change the $?, so it still contains the status of the substitution.

output=$(node ...)
status=$?
(( status )) && exit 1

Original reply

You can check the exit code with $?:

node ...
(( $? )) && exit $?

Or, you can use it directly in a condition:

if ! node ... ; then exit 1 ; fi

Or, just tell bash to exit on error:

set -e
node ...

Use set +e to restore the normal behaviour if needed.

edited Nov 23, 2016 at 22:04

answered Nov 23, 2016 at 21:39

choroba

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7 Comments

Alexander Mills Over a year ago

can you edit your answer to include the $(node) instead of just node, I feel like that does make a difference? (at least when reading your answer)

Alexander Mills Over a year ago

for example, "if ! $(node foo.js) ; then exit 1 ; fi", is probably totally different than "if ! node ... ; then exit 1 ; fi", I need to capture the stdout from the node foo.js process

choroba Over a year ago

Oh wait, you want to exit if the command substitution fails? Then assign the output to a variable: output=$(node ...), the $? then holds the exit status of the command substitution.

klefevre Over a year ago

@choroba do you have any idea why we can't use this technic with local variables? If I do so status is always equal to 0.

choroba Over a year ago

@klefevre: You need to declare the local variable before assigning to it, i.e. local output; output=$(...)

|

Jamil Said · Accepted Answer · 2016-11-23 22:05:23Z

0

The way I would tackle this problem is to add this line before the full command is run:

$(node `dirname $0`/foo.js); rc="$?"; if [ "$rc" -ne 0 ]; then exit; fi

edited Nov 23, 2016 at 22:05

answered Nov 23, 2016 at 21:58

Jamil Said

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