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

NAME

unlockpt - unlock a pseudo-terminal device pair

SYNOPSIS

#include <stdlib.h>

int
unlockpt(int fildes);

DESCRIPTION

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.

RETURN VALUES

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.

EXAMPLES

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

ERRORS

The unlockpt() function may fail if:

EBADF The fildes argument is not a file descriptor open
for writing.

EINVAL EINVAL The fildes argument is not associated with a
pseudo-terminal manager device.

INTERFACE STABILITY

Committed

MT LEVEL

Safe

SEE ALSO

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

illumos February 5, 2022 illumos