How to execute ‘base64 --decode’ on selected text in Vim?

Question

I’m trying to execute base64 --decode on a piece of text selected in Visual mode, but it is the entire line that seems to be passed to the base64 comma

Answer 1

If the text to be passed to the shell command is first yanked to a register, say, the unnamed one, one can use the following command:

:echo system('base64 --decode', @")

It is possible to combine copying the selected text and running the command into a single Visual-mode key mapping:

:vnoremap 64 y:echo system('base64 --decode', @")

The mapping can further be modified to replace the selected text with the output of the shell command via the expression register:

:vnoremap 64 c=system('base64 --decode', @")