Flameshot is a program for taking screenshots. It has an interactive GUI with controls to select the desired capture region, move and resize the capture window, make edits with common drawing tools (pencil, line, rectangle, circle, blur, undo/redo), and choose the output destination (copy to clipboard, save to disk, upload to Imgur, open with another program).
Install the package, or AUR for the development version.
Sub-commands exit immediately with no output
Option 1: Use dbus-launch
For example, using xinit:
... exec dbus-launch dwm
Seefor more information.
Option 2: Run as background process
Alternatively, you can start Flameshot as a background process at any time during your X session:
$ flameshot &