select

Basic syntax.

select variable in item_list; do
    commands ($variable holds the selected value)
    break   # Use break explicitly to exit the loop
done

Change the prompt string (default is "#? ").

PS3="Choose an option: "
select variable in item_list; do
    commands
done

Combine select with case to build an interactive menu. Use PS3 to customize the prompt string.

sample_menu.sh

#!/bin/bash
PS3="Choose an action: "

select action in "List files" "Show current directory" "Show date" "Quit"; do
    case "$action" in
        "List files")
            ls -la
            ;;
        "Show current directory")
            pwd
            ;;
        "Show date")
            date
            ;;
        "Quit")
            echo "Exiting."
            break
            ;;
        *)
            echo "Invalid selection (input: $REPLY)"
            ;;
    esac
done

Run the following command:

bash menu.sh
1) List files
2) Show current directory
3) Show date
4) Quit
Choose an action: 2
/home/alice/project
Choose an action: 4
Exiting.

Generate a menu from an array and handle invalid number input.

sample_lang_select.sh

PS3="Select a language: "
languages=("Bash" "Python" "PHP" "Kotlin" "Cancel")

select lang in "${languages[@]}"; do
    if [[ -z "$lang" ]]; then
        echo "Invalid number."
        continue
    fi
    if [[ "$lang" = "Cancel" ]]; then
        echo "Cancelled."
        break
    fi
    echo "Selected language: $lang (number: $REPLY)"
    break
done

Run the following command:

bash lang_select.sh
1) Bash
2) Python
3) PHP
4) Kotlin
5) Cancel
Select a language: 3
Selected language: PHP (number: 3)

Common Mistake 1: Forgetting break causes an infinite menu loop

Without break, select redisplays the menu after each selection and never exits.

sample_infinite_select.sh

#!/bin/bash
select item in "A" "B" "C"; do
    echo "You chose: $item"
    # no break — menu repeats forever
done

Add break after processing the selection to exit the loop.

Common Mistake 2: Entering an invalid number makes $item empty

When the user enters a number that is out of range, $item is set to an empty string. Without a check, the script may behave unexpectedly.

1) Apple
2) Banana
Select: 9
（$item is empty — 9 is out of range）

Check that $item is not empty before processing.

sample_valid_select.sh

select item in "Apple" "Banana" "Quit"; do
    [ -z "$item" ] && echo "Invalid selection" && continue
    [ "$item" = "Quit" ] && break
    echo "You chose: $item"
    break
done

select works like a while loop internally — it keeps displaying the menu until you explicitly run break or the user presses Ctrl+D (EOF).

select cannot be used in non-interactive contexts such as pipelines or cron jobs. Only use it when user interaction is expected. For non-interactive environments, design your script to accept command-line arguments instead.

For handling command-line arguments, special variables $1–$9 and case statements are useful.