Strict Mode - Bash Execution Replay

Strict shell options turn common scripting mistakes into early failures. Defaults keep missing inputs explicit without weakening the script.

Program

Play the script to watch a missing argument become a default value, then become a filename-safe slug.

strict_mode.sh

#!/usr/bin/env bash

set -euo pipefail
input="${1:-draft report}"
safe="${input// /_}"
echo "$safe"

strict mode `set -euo pipefail` makes failed commands, unset variables, and failed pipelines visible.

default expansion `${1:-draft report}` supplies a value when the first argument is missing or empty.

substitution `${input// /_}` replaces every space in the value.