The case Statement

case matches one value against several patterns — cleaner than a long if/elif chain, and ideal for handling commands and file types.

Syntax

case "$value" in
  pattern1)
    commands ;;
  pattern2 | pattern3)
    commands ;;
  *)
    default commands ;;
esac

Example

for file in photo.JPG report.pdf notes.txt song.mp3 archive.tar.gz; do
  case "$file" in
    *.jpg | *.JPG | *.png) type="image" ;;
    *.pdf | *.docx)        type="document" ;;
    *.txt | *.md)          type="text" ;;
    *.tar.gz | *.zip)      type="archive" ;;
    *)                     type="other" ;;
  esac
  echo "$file: $type"
done

Expected output

photo.JPG: image
report.pdf: document
notes.txt: text
song.mp3: other
archive.tar.gz: archive

• Each pattern ends with ), and each branch ends with ;;.
• Patterns use wildcards; | separates alternatives.
• *) catches everything else — the default.
• The block ends with esac ("case" backwards).

Handling subcommands

A very common use: scripts that take a command as their first argument.

cat > service.sh <<'EOF'
case "$1" in
  start)   echo "Starting..." ;;
  stop)    echo "Stopping..." ;;
  restart) echo "Restarting..." ;;
  *)       echo "Usage: $0 {start|stop|restart}" >&2; exit 1 ;;
esac
EOF

bash service.sh start
bash service.sh jump

Starting...
Usage: service.sh {start|stop|restart}

Practice

Write a case statement that prints weekend for Sat or Sun and weekday for anything else, and test it with day=Sun.

day="Sun"
case "$day" in
  Sat | Sun) echo "weekend" ;;
  *)         echo "weekday" ;;
esac

weekend