Bash 5 reference · Shell Builtins and Syntax

set -euo pipefail (Bash builtin)

Turn on strict mode: exit on errors (-e), fail on unset variables (-u), and fail pipelines when any part fails.

Bash 5

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Syntax

set -e  set -u  set -o pipefail  set -x

Parameter	Description
`-e`	Exit when a command fails (not in conditions).
`-u`	Error on unset variables.
`-o pipefail`	A pipeline fails if any command fails.
`-x`	Print each command before running it (debugging).

-e and pipefail

bash -c 'set -e; false; echo not printed' || echo "stopped with $?"
bash -c 'set -o pipefail; false | true' || echo "pipefail caught it ($?)"

Output

stopped with 1
pipefail caught it (1)

Run this on your computer — see “Get Started” for setup.

Tracing with -x

bash -c 'set -x; n=3; echo $((n * 2))' 2>&1

Output

+ n=3
+ echo 6
6

Run this on your computer — see “Get Started” for setup.

trap · Run commands when the script exits or receives a signal; the standard way to clean up temporary files and child processes.
Bash Error Handling: set -euo pipefail and trap · tutorial