[SOLVED] KDE Plasma Service Menu: can my code be made more concise?

hish2021 · 01-25-2022, 05:23 AM

OS: Kubuntu 20.04 with Plasma 5.18.5

I made a "service menu" to use in the Dolphin file manager.

It's purpose is to reduce the brightness of a png/jpg file using ImageMagick's `convert`

Code:

[Desktop Action less-bright]
Exec=convert -brightness-contrast -10x0 %U $(basename -s .png %U)-1.png \
&& convert -brightness-contrast -20x0 %U $(basename -s .png %U)-2.png \
&& convert -brightness-contrast -30x0 %U $(basename -s .png %U)-3.png \
&& convert -brightness-contrast -40x0 %U $(basename -s .png %U)-4.png \
&& convert -brightness-contrast -50x0 %U $(basename -s .png %U)-5.png

Name=Reduce Brightness
Icon=colorneg

[Desktop Entry]
Actions=less-bright

MimeType=image/png;image/jpeg;

ServiceTypes=KonqPopupMenu/Plugin
Type=Service
X-KDE-Priority=TopLevel

So if I right-click on an image file in Dolphin, I'll get a "Reduce Brightness" entry in the context menu (just like Thunar's custom actions).

Choosing "Reduce Brightness", will produce 5 additional image files of differing brightness:
64-brave-browser-1.png
64-brave-browser-2.png
64-brave-browser-3.png
64-brave-browser-4.png
64-brave-browser-5.png
64-brave-browser.png (original)

My question is this: my Exec line uses `&&` over and over again but is there a better way to do what my script does?

shruggy · 01-25-2022, 06:38 AM

I guess you can put the commands into a shell script and call it from Exec line. Pass %U as parameter to the script

Code:

#!/bin/sh
for u
do
  for i in 1 2 3 4 5
  do
    convert -brightness-contrast -${i}0x0 "$u" "${u%.png}-$i.png"
  done
done

In Bash, {1..5} is the same as 1 2 3 4 5

hish2021 · 01-25-2022, 07:39 AM

Thank you very much! But could you please explain the magic in
"${u%.png}-$i.png"
as compared to, say,
$(basename -s .png %U)-5.png

boughtonp · 01-25-2022, 07:52 AM

See the "${parameter%word}" section of https://www.gnu.org/software/bash/manual/html_node/Shell-Parameter-Expansion.html

(Actually, just skip this and see the BashFAQ link Shruggy posted below that explains it better.)

shruggy · 01-25-2022, 07:53 AM

See BashFAQ/073