process-connection-type

process-connection-type is a variable defined in `C source code'.
Its value is

t

Documentation:
Control type of device used to communicate with subprocesses.
Values are nil to use a pipe, or t or `pty' to use a pty.
The value has no effect if the system has no ptys or if all ptys are busy:
then a pipe is used in any case.
The value takes effect when `start-process' is called.