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.\"     @(#)gethostname.3	8.1 (Berkeley) 6/4/93
.\" $FreeBSD: src/lib/libc/gen/gethostname.3,v 1.17 2007/01/09 00:27:54 imp Exp $
.\"
.Dd August 18, 2003
.Dt GETHOSTNAME 3
.Os
.Sh NAME
.Nm gethostname ,
.Nm sethostname
.Nd get/set name of current host
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In unistd.h
.Ft int
.Fn gethostname "char *name" "size_t namelen"
.Ft int
.Fn sethostname "const char *name" "int namelen"
.Sh DESCRIPTION
The
.Fn gethostname
function
returns the standard host name for the current processor, as
previously set by
.Fn sethostname .
The
.Fa namelen
argument
specifies the size of the
.Fa name
array.
The returned name is null-terminated, unless insufficient space is provided.
.Pp
The
.Fn sethostname
function
sets the name of the host machine to be
.Fa name ,
which has length
.Fa namelen .
This call is restricted to the super-user and
is normally used only when the system is bootstrapped.
.Pp
Host names are limited in length to
.Brq Dv sysconf(_SC_HOST_NAME_MAX)
characters, not including the trailing null, currently 255.
.Sh RETURN VALUES
.Rv -std
.Sh ERRORS
The following errors may be returned by these calls:
.Bl -tag -width Er
.It Bq Er EFAULT
The
.Fa name
or
.Fa namelen
argument gave an
invalid address.
.It Bq Er ENAMETOOLONG
The current host name is longer than
.Fa namelen .
(For
.Fn gethostname
only.)
.It Bq Er EPERM
The caller tried to set the host name and was not the super-user.
.El
.Sh SEE ALSO
.Xr sysconf 3 ,
.Xr sysctl 3
.Sh STANDARDS
The
.Fn gethostname
function conforms to
.St -p1003.1-2001 .
Callers should be aware that
.Brq Dv sysconf(_SC_HOST_NAME_MAX)
may be variable or infinite, but is guaranteed to be no less than
.Brq Dv _POSIX_HOST_NAME_MAX .
On older systems, this limit was defined in the non-standard header
.In sys/param.h
as
.Dv MAXHOSTNAMELEN ,
and counted the terminating null.
The
.Fn sethostname
function and the error returns for
.Fn gethostname
are not standardized.
.Sh HISTORY
The
.Fn gethostname
function appeared in
.Bx 4.2 .
The
.Fa namelen
argument to
.Fn gethostname
was changed to
.Vt size_t
in
.Fx 5.2
for alignment with
.St -p1003.1-2001 .