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.\" $FreeBSD$ 30.\" 31.Dd July 13, 2020 32.Dt GETHOSTNAME 3 33.Os 34.Sh NAME 35.Nm gethostname , 36.Nm sethostname 37.Nd get/set name of current host 38.Sh LIBRARY 39.Lb libc 40.Sh SYNOPSIS 41.In unistd.h 42.Ft int 43.Fn gethostname "char *name" "size_t namelen" 44.Ft int 45.Fn sethostname "const char *name" "int namelen" 46.Sh DESCRIPTION 47The 48.Fn gethostname 49function 50returns the standard host name for the current processor, as 51previously set by 52.Fn sethostname . 53The 54.Fa namelen 55argument 56specifies the size of the 57.Fa name 58array. 59The returned name is null-terminated unless insufficient space is provided. 60.Pp 61The 62.Fn sethostname 63function 64sets the name of the host machine to be 65.Fa name , 66which has length 67.Fa namelen . 68This call is restricted to the super-user and 69is normally used only when the system is bootstrapped. 70.Pp 71Applications should use 72.Fn sysconf _SC_HOST_NAME_MAX 73to find the maximum length of a host name (not including the terminating null). 74.Sh RETURN VALUES 75.Rv -std 76.Sh ERRORS 77The following errors may be returned by these calls: 78.Bl -tag -width Er 79.It Bq Er EFAULT 80The 81.Fa name 82or 83.Fa namelen 84argument gave an 85invalid address. 86.It Bq Er ENAMETOOLONG 87The current host name is longer than 88.Fa namelen . 89(For 90.Fn gethostname 91only.) 92.It Bq Er EPERM 93The caller tried to set the host name and was not the super-user. 94.El 95.Sh SEE ALSO 96.Xr sysconf 3 , 97.Xr sysctl 3 98.Sh STANDARDS 99The 100.Fn gethostname 101function conforms to 102.St -p1003.1-2001 . 103Callers should be aware that 104.Brq Dv HOST_NAME_MAX 105may be variable or infinite, but is guaranteed to be no less than 106.Brq Dv _POSIX_HOST_NAME_MAX . 107On older systems, this limit was defined in the non-standard header 108.In sys/param.h 109as 110.Dv MAXHOSTNAMELEN , 111and counted the terminating null. 112The 113.Fn sethostname 114function and the error returns for 115.Fn gethostname 116are not standardized. 117.Sh HISTORY 118The 119.Fn gethostname 120function appeared in 121.Bx 4.2 . 122The 123.Fa namelen 124argument to 125.Fn gethostname 126was changed to 127.Vt size_t 128in 129.Fx 5.2 130for alignment with 131.St -p1003.1-2001 . 132