CODEWITHSUNDEEP
bashshell
LIvanov
LIvanov

Reputation: 1336

How to propagate exit code from nested bash commands

In the following scenario

$ echo $(cat some-file-that-doesnt-exist)

I'd like to have the outer command fail (exit code != 0) if the inner command fails.

Upvotes: 2

Views: 933

Answers (3)

William Pursell
William Pursell

Reputation: 212228

The cleanest way (and at the moment the only way I can think of, although it wouldn't surprise me if bash has some option setting that short-circuits the standard process and does what you want, but I would be loathe to use such a thing if it does exist) is to break up the command into pieces. That is:

$ content=$(cat /p/a/t/h) && echo "$content"

Upvotes: 1

dash-o
dash-o

Reputation: 14432

For the case of cat as the inside command, you can use the $(<filename structure. This will effectively eliminate the internal command, and will cause error processing (set -e, ERR trap, ...) to get triggered if the file does not exists

x=$(</path/to/file)

Upvotes: 0

Kamoo
Kamoo

Reputation: 872

If you only need stopping the command chain on error (instead of propagating their exit code) you can use logical AND operator &&:

x=$(cat some-file-that-doesnt-exist) && echo "$x"

Combine with logical or || you can do:

x=$(cat input.a) || x=$(cat input.b) || x=$(cat input.c) && echo "input is: $x"

Where echo only run when one or more file exists.

Upvotes: 0

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