Preserve exit code from launcher

[kankaristo]

This change is related to https://github.com/cdown/clipmenu/issues/57#issuecomment-740123283.

If clipmenu "preserves" the exit code from the launcher (exits with the same code as the launcher), the exit codes from Rofi's custom keybindings can be used with clipmenu.

For example, I'm using the following script bound to Super+v:

#!/bin/bash

trap "exit" INT

# Run clipmenu
CM_LAUNCHER=rofi clipmenu -p "Paste" -mesg "Use Shift+Delete to delete an item" \
    -kb-delete-entry "" -kb-custom-1 "Shift+Delete" \
    -kb-accept-alt "" -kb-custom-2 "Shift+Return"

exit_code=$?

case $exit_code in
    0) xdotool key "shift+Insert" ;;
    10) clipdel -d ^"$(xsel -b)"$; "$0" ;;
    *) exit $exit_code ;;
esac

With the above script, I have 3 different options when running clipmenu:

• if I press Return, the selected item is pasted to where my cursor currently is (a bit hackily with xdotool)
• if I press Shift+Return, the selected item is sent to the clipboard ("default" clipmenu behavior)
• if I press Shift+Delete, the selected item is deleted from clipmenu, and the script runs itself again (essentially keeps clipmenu open)

In order for this to work, the only change needed in clipmenu is to preserve the exit codes from the custom keybindings.

[cdown]

Looks good, thanks! Just a couple of nits.

[kankaristo]

@cdown, the requested changes as they are could lead to an error (exit "", which gives an error), so I've asked for more comments.

[kankaristo]

@cdown, I've implemented the suggested changes, and added a check so that the launcher exit code is used only if the variable is set.

[cdown]

Looks good, thanks.