Bash tool to put an icon on taskbar? - linux

Question

I am trying to create a tiny application on my Ubuntu machine. What I want to do is put to an icon on my taskbar beside the volume, and internet connectivity options. I understand that there is a notify-send command in bash that I can use, or even switch to Qt but that seems to be an overkill for the problem. Concretely, is there a way to create an icon on Ubuntu taskbar with bash, and change its color or text periodically?

Answer 1

For a very shell friendly way to quickly get tray apps working use yad (specifically yad --notification). It allows you to dynamically change icons, set click event handlers and build a custom context menu. For example:
yad --notification --command='echo hello world' --image=myicon.png
Will echo 'hello world' on click. Or:
yad --notification --command='echo hello world' --image=myicon.png --listen
Will read it's standard input waiting for commands to change icons, change visibility, open menu, trigger action and more.

Answer 2

More advanced example using yad.
Shows how to handle click in the same script and how to change the icon on the click. Also shows how to create a simple update loop and exit cleanly.
# stop on error (always good practice)
set -e
# create a FIFO file, used to manage the I/O redirection from shell
PIPE=$(mktemp -u --tmpdir ${0##*/}.XXXXXXXX)
mkfifo $PIPE
export PIPE
# attach a file descriptor to the file
exec 3<> $PIPE
# add handler to manage process shutdown
function on_exit() {
# send command to yad through pipe
echo "quit" >&3
rm -f $PIPE
}
trap on_exit EXIT
function update_icon() {
exec 3<> $PIPE # just in case
echo "icon:/path/to/some/icon" >&3
}
export -f update_icon
# add handler for tray icon left click
function on_click() {
exec 3<> $PIPE # required
echo "clicked"
echo "icon:/path/to/icon" >&3
update_icon
}
export -f on_click
# add handler for right click menu Quit entry function
on_quit() {
# signal to the script that it should end when this file is created
echo "quit" > ./quit.txt
exec 3<> $PIPE # required
echo "quit" >&3
}
export -f on_quit
# Use a file to indicate a quit command to the script
# Make sure it is gone before we start the program to avoid immediate exit
rm -f quit.txt
# create the notification icon with right click menu and Quit option
yad --notification \
--listen \
--image="/path/to/icon" \
--text="demo tray icon" \
--menu="Quit!bash -c on_quit" \
--no-middle \
--command="bash -c on_click" <&3 &
# allow user to end the loop from icon right click Quit menu option
while [ ! -f "quit.txt" ]; do
#echo "Press [CTRL+C] to stop.."
update_icon
sleep 60
done
# clean up after quit
rm quit.txt
Based on:
https://code.google.com/archive/p/yad/wikis/NotificationIcon.wiki
https://sourceforge.net/p/yad-dialog/wiki/NotificationIcon/
https://groups.google.com/g/yad-common/c/DT8q1vJ-yOQ
I'm not a bash expert, so fixes are welcome.
yad is available for many distros as a standard package. On Debian for example it can be installed by apt install yad.

Answer 3

Take a look at alltray; maybe it's your solution.
From its website:
Description
With AllTray you can dock any application with no native tray icon (like Evolution, Thunderbird, Terminals) into the system tray. A high-light feature is that a click on the "close" button will minimize back to system tray. It works well with Gnome, KDE, XFCE 4*, Fluxbox* and WindowMaker*. Xmms is supported in particular.
Options
These programs follow the usual GNU command line syntax, with long
options starting with two dashes ('-'). A summary of options is
included below.
-h --help | Show summary of options.
-v --version | Show version of program.
-d --debug | Show debug messages.
-s --show | Do not hide window after start.
-i --icon | Use a PNG image as an icon.
-l --large_icons | allow large icons (> 24x24).
-st --sticky | visible on all workspaces.
-x --borderless | Remove windows decorations border, title, frame... from parent.
-m --menu | Add entry "menu text:command" to popdown menu.
-t --title | Show title change for seconds. Probably most usefull for xmms.
-g --geometry | initial position. see man X.
Installation (command in a terminal)
- in Ubuntu:
sudo apt-get install alltray
- in Fedora:
sudo dnf install alltray
Cheers