Custom Commands on Linux Desktop

Up until recently, I was using the command line to convert and resize the images I copied from my phone to my Linux Mint box.

I used a couple of very simple one-liners for this task:

find . -maxdepth 1 -type f -name "*.jpg" -exec sh -c 'convert "$0" -resize 30% -quality 92 "${0%.*}.png"' {} \; 
find . -maxdepth 1 -type f -name "*.png" -exec sh -c 'cwebp -q 60 "$0" -o "${0%.*}.webp"' {} \;

The issue was that I always had to create a directory structure with the right files in the right places to make sure that I didn’t reprocess the same files over and over again, and that I was working on the files I actually wanted to work on.

Instead, I wanted to be able to just open a file manager, select the files I wanted to convert, then right-click, and run my commands on the selected files.

I’m using the Nemo file manager on my Cinnamon desktop, so I had an easy solution to make this process a bit more user friendly and less error-prone.

Write the script

Nemo is happy to run the users’ scripts. All I had to do was:

• Navigate to ~/.local/share/nemo/scripts/ (You can just create this directory if it doesn’t exist.)
• Create a new script file, e.g., process_images.sh.

Using find was not an option anymore, because I wanted to be able to manually select the input files and pass the list to the commands for processing. Nemo forwards this list to the script as positional arguments, so I had to loop through the $@ special parameter to process the input files one-by-one.

Next, I just had to take the commands I used in the exec clause(?) of the original commands and put them in the input file loop.

The script I ended up with was quite simple:

#!/bin/bash

# Loop through each selected file
for selected_file in "$@"
do
  # Get the full path and file extension
  full_path=$(realpath "$selected_file")
  file_ext="${full_path##*.}"

  if [[ "$file_ext" == "jpg" ]]; then
    # Convert .jpg to .png and resize
    png_path="${full_path%.*}.png"
    convert "$full_path" -resize 30% -quality 92 "$png_path"

    # Convert .png to .webp
    webp_path="${png_path%.*}.webp"
    cwebp -q 60 "$png_path" -o "$webp_path"
  fi
done

This version of the script does not contain any error handling and it’s not particularly well-written, but it should do the trick for personal use.

Add the script to Nemo’s (context) menu

Once you create a script file in Nemo’s script directory, it will be picked up and made available in the File > Scripts menu. All I had left to do was make sure that the script was executable:

chmod +x ~/.local/share/nemo/scripts/process_images.sh

(Of course you could tweak the file permissions to your needs, if you want to limit who can run the script.)

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I didn’t even have to close and reopen my Nemo windows, the script just appeared in the menu as soon as I made it executable.

If your Nemo settings are not the default ones, the Scripts menu item might not appear in the context (right-click) menus. Make sure that you enable Scripts as a visible entry in the context menus.

1. Edit > ⚙️ Preferences
2. Select Context Menus from the left-hand pane
3. Tick ✅ the checkbox next to Scripts in the Selection list

Make it pretty

It can be a bit off-putting to see a .sh file name in the Nemo menus, so to make it look prettier, you can use a link to the script file with a more user-friendly name.

1. Move the script file to a different directory. (For example, you could create a new directory in your user’s home as a designated Nemo script collection)
2. Create a symbolic link to the script file in the actual Nemo scripts directory, but with a more readable name.

# Create the new scripts directoy
mkdir ~/.my_nemo_scripts
# Move your script to the new directory
mv process_images.sh ~/.my_nemo_scripts/
# Create the symlink
ln -s ~/.my_nemo_scripts/process_images.sh ~/.local/share/nemo/scripts/'Convert and Optimize Selected Images'

Now the script should show up in the Nemo menus with the name of the symbolic link:

That’s it. You can run your scripts directly from Nemo.

Note: all of these instructions work with Nautilus a.k.a. Gnome Files, but you might need to replace nemo in the file paths with nautilus