bsd man page for ttyname

TTYNAME(3)						     Library Functions Manual							TTYNAME(3)

NAME
       ttyname, isatty, ttyslot - find name of a terminal

SYNOPSIS
       char *ttyname(filedes)

       isatty(filedes)

       ttyslot()

DESCRIPTION
       Ttyname returns a pointer to the null-terminated path name of the terminal device associated with file descriptor filedes (this is a system
       file descriptor and has nothing to do with the standard I/O FILE typedef).

       Isatty returns 1 if filedes is associated with a terminal device, 0 otherwise.

       Ttyslot returns the number of the entry in the ttys(5) file for the control terminal of the current process.

FILES
       /dev/*
       /etc/ttys

SEE ALSO
       ioctl(2), ttys(5)

DIAGNOSTICS
       Ttyname returns a null pointer (0) if filedes does not describe a terminal device in directory `/dev'.

       Ttyslot returns 0 if `/etc/ttys' is inaccessible or if it cannot determine the control terminal.

BUGS
       The return value points to static data whose content is overwritten by each call.

7th Edition							   May 15, 1985 							TTYNAME(3)