Open Source Software

hostname(7)



NAME

   hostname - hostname resolution description

DESCRIPTION

   Hostnames  are domains, where a domain is a hierarchical, dot-separated
   list of subdomains; for example, the machine  monet,  in  the  Berkeley
   subdomain    of    the    EDU    domain   would   be   represented   as
   "monet.Berkeley.EDU".

   Hostnames are often used with network client and server programs, which
   must generally translate the name to an address for use.  (This task is
   generally  performed  by  either   getaddrinfo(3)   or   the   obsolete
   gethostbyname(3).)    Hostnames  are  resolved  by  the  Internet  name
   resolver in the following fashion.

   If the name consists of a single component, that is, contains  no  dot,
   and  if  the  environment  variable HOSTALIASES is set to the name of a
   file, that file is searched for any string matching the input hostname.
   The  file  should consist of lines made up of two white-space separated
   strings, the first of which is the hostname alias, and  the  second  of
   which  is the complete hostname to be substituted for that alias.  If a
   case-insensitive match is found between the hostname to be resolved and
   the  first  field of a line in the file, the substituted name is looked
   up with no further processing.

   If the input name ends  with  a  trailing  dot,  the  trailing  dot  is
   removed,   and  the  remaining  name  is  looked  up  with  no  further
   processing.

   If the input name does not end with a trailing dot, it is looked up  by
   searching  through  a  list  of  domains  until  a match is found.  The
   default search list includes first the local domain,  then  its  parent
   domains  with at least 2 name components (longest first).  For example,
   in the domain CS.Berkeley.EDU, the name lithium.CChem will  be  checked
   first      as     lithium.CChem.CS.Berkeley.EDU     and     then     as
   lithium.CChem.Berkeley.EDU.  Lithium.CChem.EDU will not  be  tried,  as
   there  is  only  one  component  remaining  from the local domain.  The
   search  path  can  be  changed  from  the  default  by  a   system-wide
   configuration file (see resolver(5)).

SEE ALSO

   gethostbyname(3), resolver(5), mailaddr(7), named(8)

COLOPHON

   This  page  is  part of release 4.09 of the Linux man-pages project.  A
   description of the project, information about reporting bugs,  and  the
   latest     version     of     this    page,    can    be    found    at
   https://www.kernel.org/doc/man-pages/.



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