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TTYNAME(3) Library Functions Manual TTYNAME(3)

ttyname, ttyname_r, isatty, ttyslotget name of associated terminal (tty) from file descriptor

library “libc”

#include <unistd.h>

char *
ttyname(int fd);

int
ttyname_r(int fd, char *buf, size_t len);

int
isatty(int fd);

int
ttyslot(void);

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 () function determines if the file descriptor fd refers to a valid terminal type device.

The () function gets the related device name of a file descriptor for which isatty() is true.

The () function returns the name stored in a static buffer which will be overwritten on subsequent calls. The () function takes a buffer and length as arguments to avoid this problem.

The () function fetches the current process' control terminal number from the ttys(5) file entry.

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.

/dev/∗
 
/etc/ttys
 

The ttyname(), ttyname_r(), and isatty() functions may fail and return the following error codes:

[]
The fd is not a valid open file descriptor.
[]
The fd is not associated with a terminal.
[]
The bufsize argument is smaller than the length of the string to be returned.

ioctl(2), ttys(5)

The isatty(), ttyname(), and ttyslot() functions appeared in Version 7 AT&T UNIX. The ttyname_r() function appeared in FreeBSD 6.0.

March 22, 2009 DragonFly-5.6.1