bsd man page for sethostname

GETHOSTNAME(2)							System Calls Manual						    GETHOSTNAME(2)

NAME
       gethostname, sethostname - get/set name of current host

SYNOPSIS
       gethostname(name, namelen)
       char *name;
       int namelen;

       sethostname(name, namelen)
       char *name;
       int namelen;

DESCRIPTION
       Gethostname  returns  the  standard host name for the current processor, as previously set by sethostname.  The parameter namelen specifies
       the size of the name array.  The returned name is null-terminated unless insufficient space is provided.

       Sethostname sets the name of the host machine to be name, which has length namelen.  This call is restricted to the super-user and is  nor-
       mally used only when the system is bootstrapped.

RETURN VALUE
       If the call succeeds a value of 0 is returned.  If the call fails, then a value of -1 is returned and an error code is placed in the global
       location errno.

ERRORS
       The following errors may be returned by these calls:

       [EFAULT]       The name or namelen parameter gave an invalid address.

       [EPERM]	      The caller tried to set the hostname and was not the super-user.

SEE ALSO
       gethostid(2)

BUGS
       Host names are limited to MAXHOSTNAMELEN (from <sys/param.h>) characters, currently 64.

4.2 Berkeley Distribution					   May 22, 1986 						    GETHOSTNAME(2)