unlockpt(S-osr5)

unlockpt -- unlock a pseudo-terminal master/slave pair

Syntax

cc ...-lc

#include <stdlib.h>

int unlockpt(int fildes);

Description

The function unlockpt(S-osr5) clears a lock flag for the slave pseudo-terminal associated with a master pseudo-terminal, so that the slave can be opened. fildes is a file descriptor referring to a master pseudo-terminal device.

Portable applications must call unlockpt( ) before opening the slave side of a pseudo-terminal device.

Return values

On successful completion, the function unlockpt( ) returns 0; otherwise it returns -1 and sets errno.

Diagnostics

unlockpt( ) fails if fildes is not an open file descriptor or is not associated with a master pseudo-terminal device. Diagnostic codes for this function are described below.

[EBADF]: Either the file descriptor refers to no open file, or the routine tried to write to a read-only file.
[EINVAL]: The file descriptor is not associated with a master pseudo-terminal device.

Standards conformance

unlockpt(S-osr5) is conformant with: