1.\" Copyright (c) 2008 Yahoo!, Inc. 2.\" All rights reserved. 3.\" Written by: John Baldwin <jhb@FreeBSD.org> 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 3. Neither the name of the author nor the names of any co-contributors 14.\" may be used to endorse or promote products derived from this software 15.\" without specific prior written permission. 16.\" 17.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 18.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 21.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27.\" SUCH DAMAGE. 28.\" 29.\" $FreeBSD$ 30.\" 31.Dd January 8, 2008 32.Dt FEATURE_PRESENT 3 33.Os 34.Sh NAME 35.Nm feature_present 36.Nd query presence of a kernel feature 37.Sh LIBRARY 38.Lb libc 39.Sh SYNOPSIS 40.In unistd.h 41.Ft int 42.Fn feature_present "const char *feature" 43.Sh DESCRIPTION 44The 45.Fn feature_present 46function provides a method for an application to determine if a specific 47kernel feature is present in the currently running kernel. 48The 49.Fa feature 50argument specifies the name of the feature to check. 51The 52.Fn feature_present 53function will return 1 if the specified feature is present, 54otherwise it will return 0. 55If the 56.Fn feature_present 57function is not able to determine the presence of 58.Fa feature 59due to an internal error it will return 0. 60.Sh RETURN VALUES 61If 62.Fa feature 63is present then 1 is returned; 64otherwise 0 is returned. 65.Sh SEE ALSO 66.Xr sysconf 3 , 67.Xr sysctl 3 68.Sh HISTORY 69The 70.Fn feature_present 71function first appeared in 72.Fx 8.0 . 73