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+'\" t
+.\" %%%LICENSE_START(PUBLIC_DOMAIN)
+.\" This page is in the public domain. - aeb
+.\" %%%LICENSE_END
+.\"
+.TH unlockpt 3 (date) "Linux man-pages (unreleased)"
+.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 <stdlib.h>
+.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)