June 22, 2026

Writing your first Bash script

Turn a sequence of commands you type every day into a small, reliable script.

The skeleton

#!/usr/bin/env bash
set -euo pipefail

name="${1:-world}"
echo "Hello, ${name}!"

set -euo pipefail makes the script stop on errors, on unset variables and on failures inside pipelines.

Loops and conditions

for f in *.log; do
  if [[ -s "$f" ]]; then
    gzip "$f"
  fi
done

Quoting

Always quote variables: "$file" instead of $file. Unquoted variables break on spaces and are the most common source of shell bugs.

Check your work

Run shellcheck script.sh. It catches quoting mistakes and many subtle problems before they bite.

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