Bash Tui Menu

Bash TUI Menu Builder

Implements production-ready interactive Bash terminal interfaces using the dialog command and the concrete Bash-Dialog example patterns. This skill makes the model design menus that are safe under set -euo pipefail, preserve cancel/ESC semantics, clean up the terminal, and remain scriptable through non-interactive fallbacks.

TL;DR for Code Generation

• Detect dialog and an attached TTY before rendering; provide a CLI/env fallback when either is missing.
• Under set -e, capture widget output inside an if choice=$(dialog --stdout ...); then status=0; else status=$?; fi block so Cancel, ESC, Extra, and errors cannot abort before status handling.
• Treat exit code 0 as OK/Yes, 1 as Cancel/No, 3 as Extra, and 255 as ESC unless the script intentionally remaps DIALOG_* variables.
• Build menu/checklist/radiolist options as Bash arrays and pass them as "${options[@]}"; never concatenate untrusted labels into one command string.
• Use trap for INT, TERM, and EXIT cleanup so temp files and alternate-screen artifacts do not survive aborts.
• Validate selected tags with a case statement or allowlist before running commands; menu text is not authorization.
• Keep UI functions thin: collect choices in TUI functions, execute side effects in testable worker functions.

When to Use

Use this skill when:

• Building an interactive Bash script that guides users through setup, diagnostics, deployment, backups, or local administration tasks.
• Converting a numbered read prompt into a richer terminal UI with --menu, --yesno, --inputbox, --passwordbox, --checklist, or --radiolist.
• Adding a <More Info> or third action button with --extra-button and handling exit code 3.
• Capturing multi-field input from forms and password prompts while keeping passwords out of logs.
• Supporting both humans at a terminal and automation in CI through flags, environment variables, or defaults.

When NOT to Use

Avoid this skill for:

• Scripts that must be strictly POSIX sh; dialog workflows here rely on Bash arrays, [[ ]], and Bash file-descriptor patterns.
• Non-terminal automation where prompts would hang CI; expose flags or environment variables instead of forcing a TUI.
• Full-screen applications needing long-lived state, mouse-heavy interaction, or custom rendering; use a real TUI framework in Python, Go, Rust, or Node.
• Security-sensitive account creation where root privileges, password hashing, or policy enforcement are not already designed and reviewed.
• Systems where dialog cannot be installed and no fallback UX is acceptable.

Core Workflow

1. Prove the Runtime Can Render a TUI — Check that dialog exists, stdin/stdout connect to a terminal, and the script is not running in CI/non-interactive mode. Checkpoint: If any check fails, the script must use a deterministic fallback or exit with a clear setup message.

2. Model Choices as Data — Store tags, labels, and defaults in arrays before calling dialog. For checklist/radiolist widgets, include the required status field (on/off). Checkpoint: The command line must pass array elements with "${items[@]}" so spaces and punctuation in labels remain intact.

3. Render One Widget and Capture Both Result Channels — Use --stdout for simple capture, or 3>&1 1>&2 2>&3 when stdout must remain available for status text. In strict-mode scripts, put the capture assignment in an if condition and set status=0 or status=$? inside the corresponding branch. Checkpoint: Cancel, ESC, Extra, and error statuses are captured before any clear, echo, function call, or side effect runs.

4. Route by Exit Code Before Acting on Data — First branch on OK/Cancel/Extra/ESC/error, then branch on the selected tag. Checkpoint: Cancel and ESC must be intentional paths, not accidental fall-through to the default action.

5. Execute Side Effects Outside the UI Layer — TUI functions return tags or normalized values; worker functions perform installation, file changes, or command execution. Checkpoint: Worker functions can be tested without dialog by passing arguments directly.

6. Clean Up and Restore the Terminal — Use mktemp, trap, clear, and local variables. Checkpoint: Temporary files are deleted on normal exit, Cancel, ESC, Ctrl+C, and command failure.

Implementation Patterns

Pattern 1: Dependency Detection, Safe Capture, and Non-Interactive Fallback

Use this pattern for scripts that should be pleasant for humans but still safe in CI, cron, SSH commands without TTY allocation, or automation. It uses --stdout, as shown in Bash-Dialog's advanced example, because that is easier to read than saving output to a fixed file.

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

readonly APP_TITLE="Server Maintenance"

has_interactive_tty() {
    [[ -t 0 && -t 1 ]]
}

require_dialog_or_fallback() {
    if [[ "${NONINTERACTIVE:-0}" == "1" ]]; then
        return 1
    fi

    if ! has_interactive_tty; then
        return 1
    fi

    command -v dialog >/dev/null 2>&1
}

choose_maintenance_action() {
    local default_action="${MAINTENANCE_ACTION:-status}"

    if ! require_dialog_or_fallback; then
        printf '%s\n' "$default_action"
        return 0
    fi

    local options=(
        status  "Show service status"
        logs    "Open recent logs"
        restart "Restart service"
        exit    "Exit without changes"
    )

    local choice
    local status
    if choice=$(dialog --clear \
        --backtitle "$APP_TITLE" \
        --title "Main Menu" \
        --cancel-label "Exit" \
        --stdout \
        --menu "Choose a maintenance action:" 0 0 4 \
        "${options[@]}"); then
        status=0
    else
        status=$?
    fi

    case "$status" in
        0) printf '%s\n' "$choice" ;;
        1|255) printf '%s\n' "exit" ;;
        *) printf 'ERROR: dialog failed with exit code %s\n' "$status" >&2; return 1 ;;
    esac
}

run_maintenance_action() {
    local action="$1"

    case "$action" in
        status)  systemctl status my-app.service --no-pager ;;
        logs)    journalctl -u my-app.service -n 100 --no-pager ;;
        restart) systemctl restart my-app.service ;;
        exit)    return 0 ;;
        *)       printf 'ERROR: unsupported action: %s\n' "$action" >&2; return 64 ;;
    esac
}

main() {
    local action
    action=$(choose_maintenance_action)
    run_maintenance_action "$action"
}

main "$@"

Why this works: UI capability is parsed at the boundary. Internal logic receives one trusted action string and can fail fast if an impossible tag appears.

Pattern 2: BAD vs GOOD Selection Handling

The Bash-Dialog examples show two capture styles: 2>&1 >/dev/tty and --stdout. Both are valid, but they become unsafe when the script ignores exit codes, writes to fixed temp files, or runs selected text as code.

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

# ❌ BAD — fixed temp file, ignores cancel, unquoted read, and fall-through action.
dialog --menu "Choose:" 15 50 4 \
    1 "Restart service" \
    2 "Delete cache" \
    2>/tmp/menu-choice
choice=$(</tmp/menu-choice)
if [[ $choice == 1 ]]; then
    systemctl restart my-app.service
else
    rm -rf /var/cache/my-app/*
fi

# ✅ GOOD — result and status captured atomically, all branches explicit.
choose_action() {
    local choice
    local status
    if choice=$(dialog --stdout --menu "Choose:" 15 50 4 \
        restart "Restart service" \
        purge-cache "Delete cache" \
        back "Return to previous menu"); then
        status=0
    else
        status=$?
    fi

    case "$status" in
        0) printf '%s\n' "$choice" ;;
        1) printf '%s\n' "back" ;;
        255) printf '%s\n' "back" ;;
        *) printf 'ERROR: dialog failed: %s\n' "$status" >&2; return 1 ;;
    esac
}

dispatch_action() {
    local choice="$1"

    case "$choice" in
        restart)     systemctl restart my-app.service ;;
        purge-cache) find /var/cache/my-app -mindepth 1 -maxdepth 1 -delete ;;
        back)        return 0 ;;
        *)           printf 'ERROR: invalid menu choice: %s\n' "$choice" >&2; return 64 ;;
    esac
}

dispatch_action "$(choose_action)"

Pattern 3: Prompt, Password, and Confirmation Flow

Use input widgets for data collection, then parse and validate before executing. Bash-Dialog's user-creation example captures --form output with 3>&1 1>&2 2>&3 3>&- and uses --passwordbox --insecure; production code should avoid echoing secrets and should validate every field before continuing.

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

prompt_required_text() {
    local title="$1"
    local prompt="$2"
    local value
    local status

    if value=$(dialog --clear --stdout \
        --title "$title" \
        --inputbox "$prompt" 10 60 ""); then
        status=0
    else
        status=$?
    fi

    case "$status" in
        0) [[ -n "$value" ]] || { printf 'ERROR: value cannot be empty\n' >&2; return 64; }
           printf '%s\n' "$value" ;;
        1|255) return 130 ;;
        *) printf 'ERROR: input dialog failed: %s\n' "$status" >&2; return 1 ;;
    esac
}

prompt_secret() {
    local secret
    local status

    if secret=$(dialog --clear --stdout \
        --title "Credentials" \
        --passwordbox "Enter the API token:" 10 60); then
        status=0
    else
        status=$?
    fi

    case "$status" in
        0) [[ -n "$secret" ]] || { printf 'ERROR: token cannot be empty\n' >&2; return 64; }
           printf '%s\n' "$secret" ;;
        1|255) return 130 ;;
        *) printf 'ERROR: password dialog failed: %s\n' "$status" >&2; return 1 ;;
    esac
}

confirm_write() {
    local username="$1"

    dialog --clear \
        --title "Confirm" \
        --yes-label "Write" \
        --no-label "Cancel" \
        --yesno "Write configuration for ${username}?" 8 60
}

main() {
    local username token
    username=$(prompt_required_text "Profile" "Enter the username:") || exit $?
    token=$(prompt_secret) || exit $?

    if confirm_write "$username"; then
        install -m 600 /dev/null "$HOME/.my-app-token"
        printf '%s\n' "$token" > "$HOME/.my-app-token"
        dialog --msgbox "Configuration saved for ${username}." 7 50
    else
        dialog --msgbox "No files were changed." 7 40
    fi
}

main "$@"

Pattern 4: Checklist and Radiolist Builders

dialog --checklist and dialog --radiolist require triples: tag, item text, and on/off status. Keep those triples in arrays. Checklists return selected tags, commonly quoted and separated by spaces, so only use stable tags without spaces or normalize with --separate-output when processing multiple selections.

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

select_components() {
    local items=(
        nginx      "Install nginx reverse proxy" on
        certbot    "Install certbot TLS tooling" off
        logrotate  "Install log rotation config" on
        firewall   "Enable firewall profile" off
    )

    local selected
    local status
    if selected=$(dialog --clear --stdout \
        --separate-output \
        --title "Components" \
        --checklist "Select components to install:" 18 72 8 \
        "${items[@]}"); then
        status=0
    else
        status=$?
    fi

    case "$status" in
        0) printf '%s\n' "$selected" ;;
        1|255) return 130 ;;
        *) printf 'ERROR: checklist failed: %s\n' "$status" >&2; return 1 ;;
    esac
}

select_environment() {
    local choices=(
        dev     "Developer workstation" on
        staging "Shared staging server" off
        prod    "Production server" off
    )

    local environment
    local status
    if environment=$(dialog --clear --stdout \
        --title "Environment" \
        --radiolist "Choose exactly one target:" 15 64 4 \
        "${choices[@]}"); then
        status=0
    else
        status=$?
    fi

    case "$status" in
        0) printf '%s\n' "$environment" ;;
        1|255) return 130 ;;
        *) printf 'ERROR: radiolist failed: %s\n' "$status" >&2; return 1 ;;
    esac
}

main() {
    local environment
    environment=$(select_environment) || exit $?
    printf 'Environment: %s\n' "$environment"

    local components_output
    local components_status
    if components_output=$(select_components); then
        components_status=0
    else
        components_status=$?
    fi

    case "$components_status" in
        0)
            while IFS= read -r component; do
                case "$component" in
                    nginx|certbot|logrotate|firewall) printf 'Selected component: %s\n' "$component" ;;
                    "") ;;
                    *) printf 'ERROR: unknown component: %s\n' "$component" >&2; exit 64 ;;
                esac
            done <<< "$components_output"
            ;;
        130) exit 130 ;;
        *) printf 'ERROR: checklist failed: %s\n' "$components_status" >&2; exit 1 ;;
    esac
}

main "$@"

Pattern 5: Extra Button, Help Path, Cleanup, and Testability

Bash-Dialog's Extra Button examples verify that --extra-button --extra-label returns exit code 3. Use that code for contextual help or details; do not overload Cancel or force users to select an item just to learn what it does.

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

readonly TMP_DIR="$(mktemp -d)"

cleanup() {
    rm -rf "$TMP_DIR"
    if [[ -t 1 ]]; then
        clear
    fi
}
trap cleanup EXIT INT TERM

show_plan_help() {
    local selected="${1:-}"

    case "$selected" in
        quick) dialog --msgbox "Quick runs only cheap checks." 7 50 ;;
        full)  dialog --msgbox "Full runs every diagnostic and may take several minutes." 8 60 ;;
        *)     dialog --msgbox "Highlight a plan, then choose More Info." 7 55 ;;
    esac
}

choose_plan() {
    local choice status

    while true; do
        if choice=$(dialog --clear \
            --backtitle "Diagnostics" \
            --title "Run Plan" \
            --extra-button --extra-label "More Info" \
            --cancel-label "Exit" \
            --stdout \
            --menu "Choose a diagnostic plan:" 14 68 4 \
            quick "Fast status checks" \
            full  "Complete diagnostics" \
            exit  "Leave without running checks"); then
            status=0
        else
            status=$?
        fi

        case "$status" in
            0) printf '%s\n' "$choice"; return 0 ;;
            3) show_plan_help "$choice" ;;
            1|255) printf '%s\n' "exit"; return 0 ;;
            *) printf 'ERROR: dialog failed: %s\n' "$status" >&2; return 1 ;;
        esac
    done
}

run_plan() {
    local plan="$1"

    case "$plan" in
        quick) printf 'Running quick diagnostics\n' ;;
        full)  printf 'Running full diagnostics\n' ;;
        exit)  return 0 ;;
        *)     printf 'ERROR: invalid plan: %s\n' "$plan" >&2; return 64 ;;
    esac
}

run_plan "$(choose_plan)"

Constraints

MUST DO

• Use #!/usr/bin/env bash and set -euo pipefail unless integrating into an existing script with a different established shell policy.
• Check command -v dialog before rendering and provide install guidance or a non-interactive fallback.
• Capture dialog output and status separately; branch on status first, selected value second.
• Quote every variable expansion and pass menu data through arrays.
• Use stable machine tags (restart, logs, prod) rather than user-facing labels as the values executed by case statements.
• Handle Cancel, ESC, and Extra intentionally; every exit code path must be explicit.
• Use mktemp for any file capture and remove temp files with trap.
• Keep secrets out of echo, debug output, process arguments, and dialog summary boxes.

MUST NOT DO

• Do not source a remote Bash-Dialog file or assume Bash-Dialog provides a library API; the verified repository is a guide and examples for the dialog binary.
• Do not save selections to fixed paths such as /tmp/drinkChoice in production scripts.
• Do not run menu labels, user input, or selected text with eval, unquoted command substitution, or shell interpolation.
• Do not ignore the exit status of dialog; Cancel must never trigger the first or default destructive action.
• Do not force interactive dialogs in CI, cron, systemd units, or scripts called with redirected stdin/stdout.
• Do not put more than roughly 7-10 choices in one menu without grouping or adding search/filter behavior.
• Do not use recursive menu calls for long-running loops; prefer while true with clear exit paths.

Output Template

When generating or reviewing a Bash TUI menu script, return:

1. Runtime assumptions — Bash version needs, dialog dependency, TTY/non-interactive behavior.
2. Menu map — Each widget, its stable tags, and the action for OK/Cancel/ESC/Extra.
3. Implementation — Bash code with strict mode, dependency detection, arrays, traps, and worker functions.
4. Fallback behavior — Flags or environment variables that bypass the TUI for automation.
5. Verification steps — Commands to run with and without a TTY, plus a ShellCheck command when available.

Live References

Repository-standard links checked against the local SKILL_FORMAT_SPEC.md; these links preserve the Bash-Dialog research trail without treating Bash-Dialog as a sourceable library.

• Bash-Dialog repository
• Bash-Dialog README
• All Menus example
• Advanced menu example
• Advanced Extra Button example
• Dynamic Extra Button example
• User Creation form example

Reference Notes

Verified from https://github.com/RileyMeta/Bash-Dialog

• The repository is a tutorial/example collection for Bash scripts using the dialog command; the cloned tree contains README.md and example scripts under Examples/, not a sourceable Bash library module.
• The main README documents installation commands for Arch (pacman), Debian/Ubuntu (apt), and Fedora (dnf), then demonstrates the minimal widget dialog --msgbox "Hello World" 0 0.
• Documented common options include --backtitle, --title, --colors, --clear, --cr-wrap, --msgbox, --infobox, --menu, --programbox, --pause, --yesno, --inputbox, --passwordbox, --help-button, and --extra-button.
• The README describes advanced styling sequences such as \Zb/\ZB for bold and \Z0-\Z7 for ANSI colors when --colors is enabled.
• The README records default dialog-related exit-code variables: OK 0, Cancel 1, Help 2, Extra 3, ESC 255, and Error -1 through DIALOG_* environment variables.
• Examples/All_Menus/All_Menus.sh demonstrates --menu, --msgbox, --yesno, --inputbox, --passwordbox, --infobox, --textbox, --checklist, --radiolist, --gauge, --calendar, --timebox, --fselect, --dselect, and --form.
• Examples/Advanced_Examples/Advanced_Example.sh demonstrates a while true main menu, --stdout, --cancel-label, trap 'aborted' INT, and routing selected tags through nested case statements.
• Examples/Extra_Button/Advanced_Extra_Button.sh and Examples/Extra_Button/Dynamic_Extra.sh demonstrate --extra-button --extra-label and route exit code 3 separately from OK and Cancel.
• Examples/Advanced_Examples/User_Creation.sh demonstrates --form capture with file descriptor swapping and --passwordbox for hidden input.

Generic terminal-dialog patterns applied here

• Prefer --stdout for simple capture because it is readable and avoids fixed temporary files.
• Prefer --separate-output for checklists so each selected tag can be processed line-by-line.
• Prefer dependency and TTY detection at startup because dialog blocks or fails in automation contexts.
• Prefer allowlisted tags and worker functions because terminal menus are user input, not trusted execution plans.

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