Write Safe Shell Scripts

set -euf -o pipefail

set -e

If a command fails, set -e will make the whole script exit, instead of just resuming on the next line.

set -u

Treat unset variables as an error, and immediately exit.

set -f

Disable filename expansion (globbing) upon seeing *, ?, etc.

set -o pipefail

set -o pipefail causes a pipeline (for example, curl -s https://sipb.mit.edu/ | grep foo) to produce a failure return code if any command errors.

In addition echo should be avoided using printf instead.

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