How to copy a string into the X Window clipboard with the command line on Red Hat without using xsel nor any third-party tool?

Question

On a restricted system where installing new tools is not possible, how could one copy a string into the X Window clipboard (the clipboard that works with Ctrl+C / Ctrl+V) with the command line or at least in an automated way, without using xsel nor any other such third-party tool?

I am using Red Hat.

I would find it hard to believe that achieving such a basic task could not be done using native Linux only.

Answer 1

The Python standard library includes the tkinter module (Tkinter in Python 2), and you can access the X clipboard through that.

python3 -c 'import sys, tkinter; sys.stdout.write(tkinter.Tk().clipboard_get())'
python2 -c 'import sys, Tkinter; sys.stdout.write(Tkinter.Tk().clipboard_get())'

You can also set the clipboard content, but that's a bit more invasive, because the clipboard content is owned by a running application. Programs like xsel leave a background process running while they own the clipboard. Here's a simple code fragment that you need to keep running until you're no longer interested in the content; close the window when you're done.

echo -n 'new clipboard content' | python3 -c 'import tkinter; w = tkinter.Tk(); w.clipboard_clear(); w.clipboard_append(input()); w.mainloop()'
echo -n 'new clipboard content' | python2 -c 'import Tkinter, sys; w = Tkinter.Tk(); w.clipboard_clear(); w.clipboard_append(sys.stdin.read()); w.mainloop()'

(There are better ways to access the clipboard in Python, such as pyperclip which is cross-platform and doesn't require displaying a window, but they aren't part of the standard library.)