How to find the PID(s) of a hung app in macOS from the shell (Terminal)

Terminal supports an extension of the ED (Erase in Display) escape sequence to erase the scroll-back. It is also supported by xterm. The ED command, described in the VT100 manual, accepts these values for the Ps parameter:

ESC [ Ps J

Parameter   Parameter Meaning

0           Erase from the active position to the end of the screen
1           Erase from start of the screen to the active position
2           Erase all of the display

Terminal (and xterm) adds:

3           Erase the scroll-back (aka “Saved Lines”)

Note that this only erases the scroll-back, not the screen. This allows you to erase one or the other, or both by sending two escape sequences.

For example, you can clear the screen and the scroll-back with the following shell command: clear && printf '\e[3J'

(The clear command looks up the appropriate sequence for clearing the screen for the current terminal, but the “erase scroll-back” escape sequence is custom and must be hard-coded. If you put this in a shell script that you don’t know for certain will only ever be run with Terminal, you should check that $TERM_PROGRAM is Apple_Terminal before sending it.)

Editing the .bash_history is just a matter of opening the file with an editor. There are a couple of ways you could achieve this.

1. In the Terminal just type vi ~/.bash_history, then edit the file as you want, and save. This option could be tricky, if you're not used to vi, of course.
2. Make the file visible by following these instructions, for instance, open it as any other file, modify it, and save.
3. In the Terminal just type open -e ~/.bash_history. This command will open the file with TextEdit, you can choose any other text editor, of course. Modify the file and save.

For the changes to be noticeable just restart the bash.