ptsname(3C)                       SDK R4.11                      ptsname(3C)


NAME
       ptsname - get name of the slave pseudo-terminal device

SYNOPSIS
       #include <stdio.h>

       char *ptsname(int fildes);

DESCRIPTION
       The function ptsname() returns the name of the slave pseudo-terminal
       device associated with a master pseudo-terminal device.  fildes is a
       file descriptor returned from a successful open of the master device.

       The behavior of ptsname() depends on the Pseudo-Terminal
       Compatibility Mode currently in use.  This mode is a DG/UX system
       parameter, controllable using the sysadm(1m) command  ( System ->
       Parameters menu ) followed by rebooting the system.  This mode has
       two settings, as follows:

       default   With DG/UX in this mode, ptsname() returns a pointer to a
                 string containing the null-terminated path name of a slave
                 device of the form /dev/pts/N, where N is a decimal integer
                 from 1 to 5 characters in length.  This mode is compatible
                 with the SVID, Third Edition.

       BCS       ptsname() returns a pointer to a string containing the
                 null-terminated path name of a slave device of the form
                 /dev/ptsN, where N is a decimal integer from 1 to 5
                 characters in length.  Names of this form are required by
                 any pre-DG/UX 5.4.2 COFF applications (those built using
                 the m88kbcs and m88kocs SDEs and those built using the dgux
                 COFF SDE prior to 5.4.2) which contain a ttyname() function
                 that is incapable of finding Pseudo-Terminals under the
                 /dev/pts directory.


   Considerations for Threads Programming
                     +---------+-----------------------------+
                     |         |                      async- |
                     |function | reentrant   cancel   cancel |
                     |         |             point     safe  |
                     +---------+-----------------------------+
                     |ptsname  |     N         -        -    |
                     +---------+-----------------------------+

RETURN VALUE
       Upon successful completion, the function ptsname() returns a pointer
       to a string which is the name of the pseudo-terminal slave device.
       This value points to a static data area that is overwritten by each
       call to ptsname().  Upon failure, ptsname() returns NULL.  This could
       occur if fildes is an invalid file descriptor or if the slave device
       name does not exist in the file system.

SEE ALSO
       open(2), reentrant(3), grantpt(3C), ttyname(3C),
       unlockpt(3C).
       Programmer's Guide: STREAMS.
       Managing the DG/UX System.


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