This script, named `xflock4`, is a session-locking utility used in...

August 18, 2025 at 07:12 AM

#!/bin/sh
#
#  xfce4
#
#  Copyright (C) 1999, 2003 Olivier Fourdan (fourdan@xfce.org)
#  Copyright (C) 2011       Guido Berhoerster (guido+xfce.org@berhoerster.name)
#  Copyright (C) 2015, 2018 Simon Steinbeiß (simon@xfce.org)
#  Copyright (C) 2011, 2022 Jarno Suni (8@iki.fi)
#
#  This program is free software; you can redistribute it and/or modify
#  it under the terms of the GNU General Public License as published by
#  the Free Software Foundation; either version 2 of the License, or
#  (at your option) any later version.
#
#  This program is distributed in the hope that it will be useful,
#  but WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#  GNU General Public License for more details.
#
#  You should have received a copy of the GNU General Public License
#  along with this program; if not, write to the Free Software
#  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
#

print_help() {
  echo 'Usage: xflock4 [OPTION]'
  echo 'Try to lock the session in various ways, depending on the configured'
  echo 'screensavers. In particular, first try to execute the command set in the Xfconf'
  echo 'property /general/LockCommand of the xfce4-session channel.'
  echo
  echo '  -h, --help    display this help and exit'
}

case $1 in
  -h|--help)
    print_help
    exit 0
    ;;
  ?*)
    print_help >&2
    exit 1
    ;;
esac

# Wait a bit so that user have time to raise finger from a key if
# the script is run in terminal.
[ -t 0 ] && sleep 1

# echo is used to strip blanks
# $((2**31 - 1)) is MAXINT, which disables timeout: see
# https://dbus.freedesktop.org/doc/api/html/group__DBusPendingCall.html
ret=$(echo $(dbus-send --session \
                       --dest=org.xfce.SessionManager \
                       --print-reply=literal \
                       --reply-timeout=$((2**31 - 1)) \
                       --type=method_call \
                       /org/xfce/SessionManager \
                       org.xfce.Session.Manager.Lock))
[ "$ret" = 'boolean true' ]

This script, named xflock4, is a session-locking utility used in the XFCE desktop environment. Here's what the code does, section by section:

1. Script Metadata and Licensing:

The metadata section (#!/bin/sh and the block of comments) specifies that this is a shell script.
It highlights that the script is part of the XFCE project and acknowledges its copyright holders.
The license (GNU GPL) is defined, meaning the code can be redistributed and modified under specific terms.

2. Help Printing Function (`print_help`):

A function print_help is defined to display usage information when the script is run with the help flag (-h or --help) or incorrect arguments.
It prints how users might invoke the script and describes its purpose: "Try to lock the session in various ways, based on configured screensavers and settings."
This makes it user-friendly and self-documenting.

3. Command-Line Argument Handling:

A case statement handles user-provided arguments:
- If the user passes -h or --help, the print_help function is called, and the script exits with success (exit 0).
- If the user provides invalid arguments (any nonempty argument), print_help is called again, but this time the output is printed to stderr, and the script exits with an error code (exit 1).

4. User Input Adjustment (`sleep`):

If the script is run interactively in a terminal ([ -t 0 ] checks for interactive standard input), the script pauses for 1 second (sleep 1).
This is to prevent accidental key presses immediately triggering additional actions, providing the user a buffer to stop interacting before the script executes the locking mechanism.

5. Attempting to Lock the Screen:

The script attempts to lock the session by sending a D-Bus message to the org.xfce.SessionManager service using the dbus-send command.
- It sends the org.xfce.Session.Manager.Lock method call to the XFCE Session Manager's D-Bus object at /org/xfce/SessionManager.
- A large reply-timeout value is set ($((2**31 - 1))) to effectively disable reply timeout.
- The result of the D-Bus call is captured in the variable ret.

6. Validity Check:

After sending the lock request, the script evaluates the result stored in $ret.
If the D-Bus call succeeds and returns boolean true, the screen lock command was successful.

Purpose of the Script:

This script is designed to lock the user's session in an XFCE environment. It provides flexibility by using a configurable lock command (via the Xfconf property /general/LockCommand) or directly invokes the session manager's lock functionality. The help and argument handling improve usability, while the screen lock process itself integrates with XFCE's D-Bus interface.

In summary, it is a utility to safely and smoothly lock the screen, ensuring compatibility with XFCE screensaver/session manager standards.

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