tree.sh

#!/bin/sh

########################################################################
# tree.sh: Display Directory Tree
#
#  Description:
#  This script displays the directory tree of the specified directory,
#  or the current directory if no directory is specified. Hidden directories
#  (those starting with a dot) are excluded by default. An option can be
#  provided to include these hidden directories in the tree.
#
#  Author: id774 (More info: https://id774.net)
#  Source Code: https://github.com/id774/scripts
#  License: The GPL version 3, or LGPL version 3 (Dual License).
#  Contact: idnanashi@gmail.com
#
#  Usage:
#      ./tree.sh [directory] [-a]
#      ./tree.sh [-a] [directory]
#
#  Run the script without arguments to display the tree of the current
#  directory, with one directory path to display that directory, or with
#  '-a' before or after the directory to include hidden entries.
#
#  Options:
#  -a              Include hidden entries.
#  -h, --help      Display this help information.
#  -v, --version   Display version information.
#
#  Version History:
#  v2.1 2026-09-12
#       Accept -a before or after the directory and reject extra arguments.
#  v2.0 2026-08-22
#       Use POSIX find negation when excluding hidden paths.
#  v1.9 2026-07-11
#       Replace the awk {n,} interval expression in usage() with a portable
#       equivalent, since mawk on some systems matches it incorrectly.
#  v1.8 2025-06-23
#       Unified usage output to display full script header and support common help/version options.
#  v1.7 2025-04-13
#       Unify log level formatting using [INFO], [WARN], and [ERROR] tags.
#  v1.6 2025-03-22
#       Unify usage information by extracting help text from header comments.
#  v1.5 2025-03-17
#       Encapsulated all logic in functions and introduced main function.
#  v1.4 2025-03-13
#       Redirected error messages to stderr for better logging and debugging.
#  v1.3 2024-01-07
#       Added an option to include hidden directories in the tree display. Updated command existence and
#       execution permission checks using a common function for enhanced reliability and maintainability.
#  v1.2 2024-01-04
#       Added functionality to accept a directory as an argument. If no argument is provided, the script
#       displays the tree of the current directory. Added error handling for non-existent directories.
#  v1.1 2023-12-23
#       Refactored for POSIX compliance. Replaced Bash-specific syntax with POSIX standard commands
#       and structures. Enhanced portability and compatibility across different UNIX-like systems.
#  v1.0 2014-10-22
#       Initial release.
#
########################################################################

# Display full script header information extracted from the top comment block
usage() {
    check_commands awk
    awk '
        BEGIN { in_header = 0 }
        /^#+$/ && length($0) >= 10 { if (!in_header) { in_header = 1; next } else exit }
        in_header && /^# ?/ { print substr($0, 3) }
    ' "$0"
    exit 0
}

# Check if required commands exist
check_commands() {
    for cmd in "$@"; do
        cmd_path=$(command -v "$cmd" 2>/dev/null)
        if [ -z "$cmd_path" ]; then
            echo "[ERROR] Command '$cmd' is not installed. Please install $cmd and try again." >&2
            exit 127
        elif [ ! -x "$cmd_path" ]; then
            echo "[ERROR] Command '$cmd' is not executable. Please check the permissions." >&2
            exit 126
        fi
    done
}

# Determine the directory and option for hidden files
parse_arguments() {
    show_hidden=false
    directory=""
    directory_set=false

    while [ "$#" -gt 0 ]; do
        case "$1" in
            -a)
                show_hidden=true
                ;;
            -h|--help|-v|--version)
                usage
                ;;
            -*)
                usage
                ;;
            *)
                if [ "$directory_set" = true ]; then
                    usage
                fi
                directory="$1"
                directory_set=true
                ;;
        esac
        shift
    done

    if [ "$directory_set" = false ]; then
        directory="."
    fi

    if [ ! -d "$directory" ]; then
        echo "[ERROR] Directory '$directory' does not exist." >&2
        exit 1
    fi
}

# Display the directory tree
display_tree() {
    echo "$directory"
    cd "$directory" || exit 1

    if [ "$show_hidden" = true ]; then
        find . -print | sort | sed '1d;s/^\.//;s/\/\([^/]*\)$/|--\1/;s/\/[^/|]*/|  /g'
    else
        find . ! -path '*/\.*' -print | sort | sed '1d;s/^\.//;s/\/\([^/]*\)$/|--\1/;s/\/[^/|]*/|  /g'
    fi
}

# Main entry point of the script
main() {
    case "$1" in
        -h|--help|-v|--version) usage ;;
    esac

    check_commands find sort sed
    parse_arguments "$@"
    display_tree
    return 0
}

# Execute main function
main "$@"