unlockpt - unlock a pseudo-terminal master/slave pair
#include <stdlib.h> int unlockpt(int fildes);
The unlockpt() function unlocks the slave pseudo-terminal device associated with the master to which fildes refers.
Portable applications must call unlockpt() before opening the slave side of a pseudo-terminal device.
Upon successful completion, unlockpt() returns 0. Otherwise, it returns -1 and sets 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.
grantpt(), open(), ptsname(), <stdlib.h>.