NAME
ttyname,
ttyname_r, isatty,
ttyslot —
get name of associated terminal (tty)
from file descriptor
LIBRARY
library “libc”
SYNOPSIS
#include
<unistd.h>
char *
ttyname(int
fd);
int
ttyname_r(int
fd, char *buf,
size_t len);
int
isatty(int
fd);
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/OFILE 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 fd 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
ttyname()
function returns the name stored in a static buffer which will be
overwritten on subsequent calls. The
ttyname_r()
function takes a buffer and length as arguments to avoid this problem.
The
ttyslot()
function fetches the current process' control terminal number from the
ttys(5) file entry.
RETURN VALUES
The isatty() function returns 1 if the
file descriptor refers to a valid terminal device and 0 otherwise.
The ttyname() function returns the null
terminated name if the device is found and isatty()
is true; otherwise a NULL pointer is returned. The
ttyname_r() function returns 0 if successful.
Otherwise an error number 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
ERRORS
The ttyname(),
ttyname_r(), and isatty()
functions may fail and return the following error codes:
- [
EBADF] - The fd is not a valid open file descriptor.
- [
ENOTTY] - The fd is not associated with a terminal.
- [
ERANGE] - The bufsize argument is smaller than the length of the string to be returned.
SEE ALSO
HISTORY
The isatty(),
ttyname(), and ttyslot()
functions appeared in Version 7 AT&T
UNIX. The ttyname_r() function appeared in
FreeBSD 6.0.