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