tty —
return user's terminal name
The tty utility writes the name of the terminal attached
to standard input to standard output. The name that is written is the string
returned by ttyname(3). If the
standard input is not a terminal, the message ``not a tty'' is written. The
options are as follows:
-s
- Don't write the terminal name; only the exit status is affected when this
option is specified. The
-s option is deprecated
in favor of the “test -t 0”
command.
tty exits 0 if the standard input is a
terminal, 1 if the standard input is not a terminal, and >1 if an error
occurs.
The tty utility conforms to IEEE Std
1003.2-1992 (“POSIX.2”).