TTYNAME(3) BSD Library Functions Manual TTYNAME(3)NAME
isatty, ttyname, ttyslot — get name of associated terminal (tty) from
file descriptor
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <unistd.h>
int
isatty(int fildes);
char *
ttyname(int fildes);
int
ttyslot(void);
DESCRIPTION
These functions operate on the system file descriptors for terminal type
devices. These descriptors are not related to the standard I/O FILE
typedef, but refer to the special device files found in /dev and named
/dev/ttyxx and for which an entry exists in the initialization file
/etc/ttys. (See ttys(5).)
The isatty() function determines if the file descriptor fildes refers to
a valid terminal type device.
The ttyname() function gets the related device name of a file descriptor
for which isatty() is true.
The ttyslot() function fetches the current process' control terminal num‐
ber from the ttys(5) file entry.
RETURN VALUES
The ttyname() function returns the null terminated name if the device is
found and isatty() is true; otherwise, a NULL pointer is returned.
The ttyslot() function returns the unit number of the device file if
found; otherwise, the value zero is returned.
FILES
/dev/∗
/etc/ttys
SEE ALSOioctl(2), ttys(5)HISTORY
A isatty(), ttyname(), and ttyslot() function appeared in Version 7 AT&T
UNIX.
BUGS
The ttyname() function leaves its result in an internal static object and
returns a pointer to that object. Subsequent calls to ttyname() will
modify the same object.
BSD June 4, 1993 BSD
