tty(1)

NAME

tty − get the name of the terminal

tty [ −l ] [ −s ]

tty prints the path name of the user’s terminal.

−l prints the synchronous line number to which the user’s terminal is connected, if it is on an active synchronous line.

−s inhibits printing of the terminal path name, allowing one to test just the exit code.

2 if invalid options were specified,

0 if standard input is a terminal,

1 otherwise.

“not on an active synchronous line” if the standard input is not a synchronous terminal and −l is specified.

“not a tty” if the standard input is not a terminal and −s is not specified.

CX/UX User’s Reference Manual