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.Dd $Mdocdate: September 4 2015 $
.Dt GETHOSTNAME 3
.Os
.Sh NAME
.Nm gethostname ,
.Nm sethostname
.Nd get/set name of current host
.Sh SYNOPSIS
.In unistd.h
.Ft int
.Fn gethostname "char *name" "size_t namelen"
.Ft int
.Fn sethostname "const char *name" "size_t namelen"
.Sh DESCRIPTION
The
.Fn gethostname
function returns the standard host name for the current
machine, as previously set by
.Fn sethostname .
The parameter
.Fa namelen
specifies the size of the
.Fa name
array.
If insufficient space is provided, the returned name is truncated.
The returned name is always NUL terminated.
If no space is provided, an error is returned.
.Pp
.Fn sethostname
sets the name of the host machine to be
.Fa name ,
which has length
.Fa namelen .
This call is restricted to the superuser and
is normally used only when the system is bootstrapped.
.Sh RETURN VALUES
If the call succeeds a value of 0 is returned.
If the call fails, a value of \-1 is returned and an error code is
placed in the global variable
.Va errno .
.Sh ERRORS
The following errors may be returned by these calls:
.Bl -tag -width Er
.It Bq Er EFAULT
The
.Fa name
parameter gave an invalid address.
.It Bq Er ENOMEM
The
.Ar namelen
parameter was zero.
.It Bq Er EPERM
The caller tried to set the hostname and was not the superuser.
.El
.Sh SEE ALSO
.Xr hostname 1 ,
.Xr getdomainname 3 ,
.Xr gethostid 3 ,
.Xr sysctl 3 ,
.Xr sysctl 8 ,
.Xr yp 8
.Sh STANDARDS
The
.Fn gethostname
function call conforms to
.St -xpg4.2 .
.Sh HISTORY
The
.Fn gethostname
function call appeared in
.Bx 4.2 .
.Sh BUGS
Host names are limited to
.Dv MAXHOSTNAMELEN
(from
.In sys/param.h )
characters, currently 256.
This includes the terminating NUL character.
Note that the corresponding POSIX definition
.Dv HOST_NAME_MAX
in
.In limits.h
does
.Em not
include the terminating NUL character.
.Pp
If the buffer passed to
.Fn gethostname
is smaller than
.Dv MAXHOSTNAMELEN ,
other operating systems may not guarantee termination with NUL.