1.\" Copyright (c) 1983, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.\" @(#)gethostname.3 8.1 (Berkeley) 6/4/93 29.\" $FreeBSD: src/lib/libc/gen/gethostname.3,v 1.17 2007/01/09 00:27:54 imp Exp $ 30.\" $DragonFly: src/lib/libc/gen/gethostname.3,v 1.4 2006/05/26 19:39:36 swildner Exp $ 31.\" 32.Dd August 18, 2003 33.Dt GETHOSTNAME 3 34.Os 35.Sh NAME 36.Nm gethostname , 37.Nm sethostname 38.Nd get/set name of current host 39.Sh LIBRARY 40.Lb libc 41.Sh SYNOPSIS 42.In unistd.h 43.Ft int 44.Fn gethostname "char *name" "size_t namelen" 45.Ft int 46.Fn sethostname "const char *name" "int namelen" 47.Sh DESCRIPTION 48The 49.Fn gethostname 50function 51returns the standard host name for the current processor, as 52previously set by 53.Fn sethostname . 54The 55.Fa namelen 56argument 57specifies the size of the 58.Fa name 59array. 60The returned name is null-terminated unless insufficient space is provided. 61.Pp 62The 63.Fn sethostname 64function 65sets the name of the host machine to be 66.Fa name , 67which has length 68.Fa namelen . 69This call is restricted to the super-user and 70is normally used only when the system is bootstrapped. 71.Pp 72Host names are limited to 73.Brq Dv HOST_NAME_MAX 74characters, not including the trailing null, currently 255. 75.Sh RETURN VALUES 76.Rv -std 77.Sh ERRORS 78The following errors may be returned by these calls: 79.Bl -tag -width Er 80.It Bq Er EFAULT 81The 82.Fa name 83or 84.Fa namelen 85argument gave an 86invalid address. 87.It Bq Er ENAMETOOLONG 88The current host name is longer than 89.Fa namelen . 90(For 91.Fn gethostname 92only.) 93.It Bq Er EPERM 94The caller tried to set the host name and was not the super-user. 95.El 96.Sh SEE ALSO 97.Xr sysconf 3 , 98.Xr sysctl 3 99.Sh STANDARDS 100The 101.Fn gethostname 102function conforms to 103.St -p1003.1-2001 . 104Callers should be aware that 105.Brq Dv HOST_NAME_MAX 106may be variable or infinite, but is guaranteed to be no less than 107.Brq Dv _POSIX_HOST_NAME_MAX . 108On older systems, this limit was defined in the non-standard header 109.In sys/param.h 110as 111.Dv MAXHOSTNAMELEN , 112and counted the terminating null. 113The 114.Fn sethostname 115function and the error returns for 116.Fn gethostname 117are not standardized. 118.Sh HISTORY 119The 120.Fn gethostname 121function appeared in 122.Bx 4.2 . 123The 124.Fa namelen 125argument to 126.Fn gethostname 127was changed to 128.Vt size_t 129in 130.Fx 5.2 131for alignment with 132.St -p1003.1-2001 . 133