Macos – Terminal fails with a “Could not create a new process and open a pseudo-tty.” message

The easiest way is by using "ttab"

https://www.npmjs.com/package/ttab

Just run ttab 'ls -la' here ls -la is the command that I want to execute in a new tab.

Note: ttab needs the installation of NPM

I used to deal with this type of situation occasionally, and when it's a general UI freeze, not one particular window being unresponsive, then there's nothing I've found (no process you can kill) that can deal with the problem, other than killing WindowServer. That should cause the session to be logged out.

However, in this particular case, since killing WindowServer didn't return the system to a usable state, I suspect it was doomed anyway.

With regard to the best possible recovery, one thing to note is that it may be possible to cleanly shut down individual applications from SSH:

osascript -e 'tell application "TextEdit" to quit'

Normal GUI applications will not save their files etc. when killed, but will when given this quit event. Of course, if the application pops up a dialog when you tell it to quit, this doesn't help. And if osascript itself hangs, then the Apple Event dispatch system is hung...