'\" t .\" %%%LICENSE_START(PUBLIC_DOMAIN) .\" This page is in the public domain. - aeb .\" %%%LICENSE_END .\" .TH unlockpt 3 2024-05-02 "Linux man-pages 6.9.1" .SH NAME unlockpt \- unlock a pseudoterminal master/slave pair .SH LIBRARY Standard C library .RI ( libc ", " \-lc ) .SH SYNOPSIS .nf .B #define _XOPEN_SOURCE .B #include .P .BI "int unlockpt(int " fd ); .fi .P .RS -4 Feature Test Macro Requirements for glibc (see .BR feature_test_macros (7)): .RE .P .BR unlockpt (): .nf Since glibc 2.24: _XOPEN_SOURCE >= 500 .\" || (_XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED) glibc 2.23 and earlier: _XOPEN_SOURCE .fi .SH DESCRIPTION The .BR unlockpt () function unlocks the slave pseudoterminal device corresponding to the master pseudoterminal referred to by the file descriptor .IR fd . .P .BR unlockpt () should be called before opening the slave side of a pseudoterminal. .SH RETURN VALUE When successful, .BR unlockpt () returns 0. Otherwise, it returns \-1 and sets .I errno to indicate the error. .SH ERRORS .TP .B EBADF The .I fd argument is not a file descriptor open for writing. .TP .B EINVAL The .I fd argument is not associated with a master pseudoterminal. .SH ATTRIBUTES For an explanation of the terms used in this section, see .BR attributes (7). .TS allbox; lbx lb lb l l l. Interface Attribute Value T{ .na .nh .BR unlockpt () T} Thread safety MT-Safe .TE .SH STANDARDS POSIX.1-2008. .SH HISTORY glibc 2.1. POSIX.1-2001. .SH SEE ALSO .BR grantpt (3), .BR posix_openpt (3), .BR ptsname (3), .BR pts (4), .BR pty (7)