how can I add options to the right-click drop down menu in gnome?

Question

GNOME Shell 3.26.2 | Ubuntu 17.10 | Bash 4.4.12

How can I add options to the right-click drop down menu in GNOME GUI? I want to place an item in the mouse right-click menu that will do echo "$variable" >> ~/notes/notepad.txt where $variable is the currently highlighted text. Is there a way to apply this to the right-click menu globally, like copy/paste? I want to have this option basically anywhere a cut/copy option for text is available.

Answer 1

As far as I know the dropdown menus are program-specific, so to add a system-wide dropdown menu item you would need to adjust nearly every single program's menu accordingly, and there may very well be programs where the menu is hard-coded and not easily modifiable.

I suggest you define a global keyboard shortcut instead, there are several question on this topic here, e.g. GNOME 3 Shell keyboard/mouse shortcuts for GNOME Shell. To capture the currently selected text I recommend xclip, the command is:

xclip -o >>~/notes/notepad.txt

Note that this does not append the content of the clipboard buffer (which is filled e.g. with Ctrl+C) to the file, but the content of the primary buffer instead, which always contains the text you mark(ed). More about this important difference can be found on Unix.SE: What's the difference between Primary Selection and Clipboard Buffer?, wiki.archlinux.org and in this excellent article.
If you want to append the content of the clipboard buffer, use:

xclip -se c -o >>~/notes/notepad.txt

Explanations

• -se c – short for -selection clipboard, uses the clipboard buffer instead of the (default) primary one
• -o – output from the selected buffer instead of writing to it (default)
• >>~/notes/notepad.txt – redirect the output to the file ~/notes/notepad.txt appending to its content

See man xclip for more information.