unlockpt - unlock a pseudo-terminal master/slave pair
The unlockpt() function shall unlock the slave pseudo-terminal device associated with the master to which fildes refers.
Conforming applications shall ensure that they call unlockpt() before opening the slave side of a pseudo-terminal device.
Upon successful completion, unlockpt() shall return 0. Otherwise, it shall return -1 and set errno to indicate the error.
The unlockpt() function may fail if:
- The fildes argument is not a file descriptor open for writing.
- The fildes argument is not associated with a master pseudo-terminal device.
See the RATIONALE section for posix_openpt.
grantpt, open, posix_openpt, ptsname
First released in Issue 4, Version 2.
Moved from X/OPEN UNIX extension to BASE.
The normative text is updated to avoid use of the term "must" for application requirements.
POSIX.1-2008, Technical Corrigendum 1, XSH/TC1-2008/0697  is applied.
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