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.
The
tty
utility exits 0 if the standard input is a terminal, 1 if the standard input
is not a terminal, or >1 if an error occurred.