Function: comint-exec

Start up a process named NAME in buffer BUFFER for Comint modes.
Runs the given COMMAND with SWITCHES, and initial input from STARTFILE.

COMMAND should be one of the following:
- a string, denoting an executable program to create via
- a cons pair of the form (HOST . SERVICE), denoting a TCP
connection to be opened via `open-network-stream'
- nil, denoting a newly-allocated pty.

This function blasts any old process running in the buffer, and
does not set the buffer mode. You can use this to cheaply run a
series of processes in the same Comint buffer. The hook
`comint-exec-hook' is run after each exec. (fn BUFFER NAME COMMAND STARTFILE SWITCHES)