(This is part of a larger series on finding your footing on Arch Linux.)
Last modified: 13 July 2024
Goal: learn how to programmatically set an image as your background wallpaper in the X window system, then (optionally) create a slideshow to cycle the wallpaper through a set of images.
Dependencies: This guide works on the X Window System. You should first set up X if you have not yet done so.
References:
man feh
You can set your background wallpaper using the feh
image viewer.
First install the feh
package.
You can then set the background to an arbitrary image file with the command:
feh --bg-fill 'path/to/image.jpg'
Details
Using --bg-fill
fills the image into your background without repeating it or using borders, and preserves the image’s aspect ratio.
You could also experiment with related feh
commands like --bg-center
, --bg-scale
, and --bg-tile
; see the BACKGROUND SETTING
section of man feh
for details.
Supported formats: feh
supports the JPEG, PNG, and TIFF (among others), which should cover most use cases.
See the SUPPORTED FORMATS
section in man feh
for more on supported formats.
Context: a wallpaper set with feh
will disappear after exiting your X session (e.g. after rebooting).
This section shows how to make your wallpaper persist between reboots.
The feh
background setting commands (e.g. --bg-fill
above) save the exact feh
command needed to reproduce the last-set wallpaper in the simple shell script file ~/.fehbg
.
You can then run ~/.fehbg
when starting X to reproduce the last set background.
You’ll probably want to run ~/.fehbg
automatically from an X startup file.
Simply place the line ~/.fehbg &
in your ~/.xinitrc
file (if you start X with the startx
program) or your ~/.xprofile
file (if you start X with a display/login manager) before the line that starts your window manager or desktop environment, i.e.
# This code would go in your ~/.xinitrc or ~/.xprofile
# Set wallpaper with feh
~/.fehbg &
The appending &
character ensures that ~/.fehbg
runs as a background process to avoid halting the X start-up.
Check-in point: first, you should be able to set your wallpaper with some variant of feh --bg-fill image.jpg
, and this command should create an executable .fehbg
script in your home directory.
Second, placing the line in your X startup file should make the last-set wallpaper persist after restarting X.
Goal: create a “wallpaper slideshow” that changes the background wallpaper every few minutes, which the background image chosen at random from a directory of image files.
(Of course, using a slideshow only makes sense when you can see your desktop background, e.g. if using transparent windows, gaps, or floating windows.)
First create a dedicated wallpaper directory and fill it with images you would like to use as wallpapers.
I’ll use the location ~/Pictures/wallpapers
in this guide, but any readable location on your file system should work fine.
The relevant wallpaper-setting command here is:
DISPLAY=:0 feh --no-fehbg --bg-fill --randomize ~/Pictures/wallpapers/*.jpg
This command sets the background to an image chosen randomly from all files with the jpg
extension inside the wallpapers
directory.
Some comments:
*.png
to match PNG files, *.{png,jpg}
for both PNG and JPEG files, *
to match all files, etc.--randomize
is a randomization flag documented in the OPTIONS
section of man feh
.DISPLAY=:0
ensures the feh
command applies to the primary X display on the local computer
(DISPLAY=:0
is standard X lingo for the first display on the local computer).
You could adjust the value of DISPLAY
to also set the wallpaper on multi-monitor setups.Try repeatedly running the script manually and checking that your background updates accordingly.
You then just need to wrap the above command in a systemd
timer and you have a working slideshow.
Goal: create a systemd
service/timer pair to periodically run the above wallpaper-setting command over a time interval of your choice.
Note that the rest of this guide closely parallels this series’s battery alert guide, since both use a systemd
timer to run a Type=oneshot
user service.
First create the shell script ~/scripts/change-wallpaper.sh
(or use any other readable location on your file system), make the script executable, and inside place the wallpaper-setting command:
#!/bin/sh
# This file lives at `~/scripts/change-wallpaper.sh`
# Sets background wallpaper of X display :0 to a random JPG file chosen from
# the directory `~/Pictures/wallpapers`
DISPLAY=:0 feh --no-fehbg --bg-fill --randomize ~/Pictures/wallpapers/*.jpg
Then create the systemd
user service ~/.config/systemd/user/change-wallpaper.service
, and inside it place the following:
[Unit]
Description=Change the wallpaper on X display :0
Wants=change-wallpaper.timer
[Service]
Type=oneshot
# Adjust path to script as needed
ExecStart=/bin/sh ~/scripts/change-wallpaper.sh
[Install]
WantedBy=graphical.target
This service unit runs the change-wallpaper.sh
script; setting the unit’s Type
to oneshot
ensures the battery alert service completes before any other systemd
units run; Type=oneshot
is standard practice for units that start short-running shell scripts.
The ~/.config/systemd/user
directory is the standard location for user units.
Next create the corresponding systemd
user timer ~/.config/systemd/user/change-wallpaper.timer
, and inside it place the following:
[Unit]
Description=Change the wallpaper on X display :0 every few minutes
Requires=change-wallpaper.service
[Timer]
# Changes wallpaper every 5 minutes; adjusts as needed
OnActiveSec=5m
OnUnitActiveSec=5m
[Install]
WantedBy=timers.target
This timer will run the change-wallpaper
service 5 minutes after the timer first activates (from OnActiveSec
), and then periodically every 5 minutes after that (from OnUnitActiveSec
).
You may want to set short intervals (e.g. ten seconds 10s
) when testing that the timer works properly, then set a longer time after that.
Use daemon-reload
to tell systemd
you’ve created new unit files, then start and enable the timer service:
systemctl --user daemon-reload
systemctl --user enable --now change-wallpaper.timer
# Optionally check that the timer is active
systemctl --user list-timers
Note that you only enable and start the change-wallpaper.timer
unit and not the .service
unit.
The wallpaper slideshow should be ready after this step.
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