ttyname(3C)                    DG/UX R4.11MU05                   ttyname(3C)


NAME
       ttyname, ttynamer, isatty - find name of a terminal

SYNOPSIS
       #include <stdlib.h>

       char *ttyname (int fildes);

       char *ttynamer (int fildes, char *buffer, int buflen);

       int isatty (int fildes);

DESCRIPTION
       ttyname and ttynamer return a pointer to a string containing the
       null-terminated pathname of the terminal device associated with file
       descriptor fildes.  Instead of returning static data, ttynamer
       returns the string into the location pointed to by buffer. The return
       value of ttynamer is the same as buffer. buffer has a length of
       buflen characters.  If ttynamer detects an error, a NULL is returned
       and errno is set to indicate the error.

       isatty returns 1 if fildes is associated with a terminal device, 0
       otherwise.


   Considerations for Threads Programming
                     +----------+-----------------------------+
                     |          |                      async- |
                     |function  | reentrant   cancel   cancel |
                     |          |             point     safe  |
                     +----------+-----------------------------+
                     |isatty    |     Y         N        N    |
                     |ttyname   |     N         -        -    |
                     |ttynamer |     Y         Y        N    |
                     +----------+-----------------------------+

FILES
       /dev/* - Terminal device files.
       /etc/ttysrch - List of directories under /dev containing tty device
       files.
       /etc/ttymap - Binary database mapping names of device files under
       /dev with their major and minor device numbers.

DIAGNOSTICS
       ttyname, isatty and ttynamer return a NULL pointer if fildes does
       not describe a terminal device in the /dev directory.

   Errors
       If the following condition occurs, ttynamer returns NULL and set
       errno to the corresponding value:

       [ERANGE]  The value of buflen is smaller than the length of the
                 string to be returned.

SEE ALSO
       reentrant(3), ttyslot(3C), ttysrch(4M), ttymap(1M).

NOTES
       The function ttynamer is available only in the shared library,
       libc.so.

       The return value for ttyname and isatty points to static data whose
       content is overwritten by each call.


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