unlockpt(3) Library Functions Manual unlockpt(3)

unlockpt - unlock a pseudoterminal master/slave pair

Standard C library (libc, -lc)

#include <stdlib.h>
int unlockpt(int fd);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):


    Since glibc 2.24:
        _XOPEN_SOURCE >= 500
    glibc 2.23 and earlier:

The unlockpt() function unlocks the slave pseudoterminal device corresponding to the master pseudoterminal referred to by the file descriptor fd.

unlockpt() should be called before opening the slave side of a pseudoterminal.

When successful, unlockpt() returns 0. Otherwise, it returns -1 and sets errno to indicate the error.

The fd argument is not a file descriptor open for writing.
The fd argument is not associated with a master pseudoterminal.

For an explanation of the terms used in this section, see attributes(7).

Interface Attribute Value
unlockpt () Thread safety MT-Safe


glibc 2.1. POSIX.1-2001.

grantpt(3), posix_openpt(3), ptsname(3), pts(4), pty(7)

2024-05-02 Linux man-pages 6.9.1