NAME

unlockpt — unlock a pseudo-terminal manager/subsidiary pair

SYNOPSIS

[XSI] #include <stdlib.h>

int unlockpt(int fildes);

DESCRIPTION

The unlockpt() function shall unlock the subsidiary pseudo-terminal device associated with the manager device to which fildes refers.

Conforming applications shall ensure that they call unlockpt() before opening the subsidiary side of a pseudo-terminal device.

RETURN VALUE

Upon successful completion, unlockpt() shall return 0. Otherwise, it shall return -1 and set errno to indicate the error.

ERRORS

The unlockpt() function may fail if:

[EBADF]

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

[EINVAL]

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

EXAMPLES

None.

APPLICATION USAGE

None.

RATIONALE

See the RATIONALE section for posix_openpt.

FUTURE DIRECTIONS

None.

SEE ALSO

grantpt, open, posix_openpt, ptsname

XBD <stdlib.h>

CHANGE HISTORY

First released in Issue 4, Version 2.

Issue 5

Moved from X/OPEN UNIX extension to BASE.

Issue 6

The normative text is updated to avoid use of the term "must" for application requirements.

Issue 7

POSIX.1-2008, Technical Corrigendum 1, XSH/TC1-2008/0697 [96] is applied.

Issue 8

Austin Group Defect 1466 is applied, changing the terminology used for pseudo-terminal devices.