ttyname(), isatty(), ttyslot() - get pathname of associated terminal (tty) from file descriptor
#include <unistd.h>
char * ttyname (int fd)
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.
The isatty(2) function determines if the file descriptor fd refers to a valid terminal type device (serial devices, console windows and pseudo ttys).
The ttyname(2) function gets the related device name
of a file descriptor for which isatty(2) is true. The name
has the form /dev/ttyident, where
the ident string specifies the type of the device and
identifies it.
The ttyslot(3) function returns the index for the curent user's place in /var/adm/utmpx file, the user accounting database. The first entry is 0; the record represents the user's line. (A user's line in the database is an entry where utline matches the terminal device for one of the standard streams.)
The ttyname(2) function returns the null-terminated name if the tty device is found and isatty(2) is true; otherwise it returns NULL and sets errno.
the ttyslot(3) function returns the index number for the entry; on failure, it returns -1 if there was an error, or if none of standard input, output or error for the process is associated with a terminal device.
The isatty(2) call returns zero if fd is not a valid terminal device and non-zero if it is.
The ttyname(2) function can fail for the following reasons:
ctermid(3)