TTYNAME(3)                     Library Routines                     TTYNAME(3)




NAME

       ttyname,  isatty,  ttyslot - get name of associated terminal (tty) from
       file descriptor


SYNOPSIS

       #include <unistd.h>

       char * ttyname (int fd);
       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/O
       FILE typedef, but refer to the special  device  named  .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 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


SEE ALSO

       ioctl(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 mod-
       ify the same object.



GNO                             29 January 1997                     TTYNAME(3)

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