UNLOCKPT(3C) Standard C Library Functions UNLOCKPT(3C)

unlockpt
unlock a pseudo-terminal device pair

#include <stdlib.h>

int
unlockpt(int fildes);

When a pseudo-terminal manager device is opened, whether through posix_openpt(3C) or open(2) on a ptm(4D) device, the subsidiary device begins operation in a locked state. The unlockpt() function unlocks the pseudo-terminal subsidiary device associated with the manager device to which fildes refers.

Portable applications must call unlockpt() before opening the pseudo-terminal subsidiary device.

The unlockpt() function returns the value 0 if successful; otherwise the value -1 is returned and the global variable errno is set to indicate the error.

See posix_openpt(3C) for an example that includes a call to unlockpt().

The unlockpt() function may fail if:
The fildes argument is not a file descriptor open for writing.
EINVAL The fildes argument is not associated with a pseudo-terminal manager device.

Committed

Safe

open(2), grantpt(3C), posix_openpt(3C), ptsname(3C), ptm(4D), attributes(7), standards(7)
February 5, 2022 OmniOS