In Emacs, you can do this by invoking shell-command-on-region, by default bound to C-u M-| - iirc if no region is active it replaces the buffer, but I rarely us

In Emacs, you can do this by invoking shell-command-on-region, by default bound to C-u M-| - iirc if no region is active it replaces the buffer, but I rarely use it that way so I might be wrong about that. At worst, C-x h C-u M-| gets you there.