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(7D) device, the subsidiary device begins operation in a locked state. The () function unlocks the pseudo-terminal subsidiary device associated with the manager device to which fildes refers.

Portable applications must call () 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.

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

February 5, 2022 illumos