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.Dd July 13, 2020 29.Dt GETHOSTNAME 3 30.Os 31.Sh NAME 32.Nm gethostname , 33.Nm sethostname 34.Nd get/set name of current host 35.Sh LIBRARY 36.Lb libc 37.Sh SYNOPSIS 38.In unistd.h 39.Ft int 40.Fn gethostname "char *name" "size_t namelen" 41.Ft int 42.Fn sethostname "const char *name" "int namelen" 43.Sh DESCRIPTION 44The 45.Fn gethostname 46function 47returns the standard host name for the current processor, as 48previously set by 49.Fn sethostname . 50The 51.Fa namelen 52argument 53specifies the size of the 54.Fa name 55array. 56The returned name is null-terminated unless insufficient space is provided. 57.Pp 58The 59.Fn sethostname 60function 61sets the name of the host machine to be 62.Fa name , 63which has length 64.Fa namelen . 65This call is restricted to the super-user and 66is normally used only when the system is bootstrapped. 67.Pp 68Applications should use 69.Fn sysconf _SC_HOST_NAME_MAX 70to find the maximum length of a host name (not including the terminating null). 71.Sh RETURN VALUES 72.Rv -std 73.Sh ERRORS 74The following errors may be returned by these calls: 75.Bl -tag -width Er 76.It Bq Er EFAULT 77The 78.Fa name 79or 80.Fa namelen 81argument gave an 82invalid address. 83.It Bq Er ENAMETOOLONG 84The current host name is longer than 85.Fa namelen . 86(For 87.Fn gethostname 88only.) 89.It Bq Er EPERM 90The caller tried to set the host name and was not the super-user. 91.El 92.Sh SEE ALSO 93.Xr sysconf 3 , 94.Xr sysctl 3 95.Sh STANDARDS 96The 97.Fn gethostname 98function conforms to 99.St -p1003.1-2001 . 100Callers should be aware that 101.Brq Dv HOST_NAME_MAX 102may be variable or infinite, but is guaranteed to be no less than 103.Brq Dv _POSIX_HOST_NAME_MAX . 104On older systems, this limit was defined in the non-standard header 105.In sys/param.h 106as 107.Dv MAXHOSTNAMELEN , 108and counted the terminating null. 109The 110.Fn sethostname 111function and the error returns for 112.Fn gethostname 113are not standardized. 114.Sh HISTORY 115The 116.Fn gethostname 117function appeared in 118.Bx 4.2 . 119The 120.Fa namelen 121argument to 122.Fn gethostname 123was changed to 124.Vt size_t 125in 126.Fx 5.2 127for alignment with 128.St -p1003.1-2001 . 129