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


NAME
       unlockpt - unlock a pseudo-terminal master/slave pair

SYNOPSIS
       int unlockpt(int fildes);

DESCRIPTION
       The function unlockpt() clears a lock flag associated with the slave
       pseudo-terminal device associated with its master pseudo-terminal
       counterpart so that the slave pseudo-terminal device can be opened.
       fildes is a file descriptor returned from a successful open of a
       master pseudo-terminal device.


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

RETURN VALUE
       Upon successful completion, the function unlockpt() returns 0;
       otherwise it returns -1.  A failure may occur if fildes is not an
       open file descriptor or is not associated with a master pseudo-
       terminal device.

SEE ALSO
       open(2), reentrant(3).
       grantpt(3C), ptsname(3C)
       in the Programmer's Guide: STREAMS.


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