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modify_resolvconf



SYNOPSIS

       modify_resolvconf modify -s <service> -t <text>|- -p <pro­
       cess> [ -i <pid> ] -f <filename of script>  [  -e  <exten­
       sion>  ] [ -l <list of search domains> | -d <domainname> ]
       [ -n <list of nameservers> ] [ -a <filename> ] [ -o <file­
       name> ] [ --resolv ] [ --named ] [ --no_restart ] [ -v ] [
       -q ]

       modify_resolvconf restore -s <service> [ -e <extension>  ]
       [  -n  show  ]  [  -o  <filename>  ] [ -k ] [ --resolv ] [
       --named ] [ --no_restart ] [ -v ] [ -q ]

       modify_resolvconf cleanup [ -n show P ] [ -o <filename>  ]
       [  -k ] [ --resolv ] [ --named ] [ --no_restart ] [ -v ] [
       -q ]

       modify_resolvconf check [ --resolv ] [ --named ] [ -v ]  [
       -q ]

       modify_resolvconf -h, --help


DESCRIPTION

       modify_resolvconf  can  be  used  by programs that have to
       change  /etc/resolv.conf  or  /etc/named.conf  dynamically
       (temporarily). It provides a means to do that in a consis­
       tent way accross the system. The idea is to

       - make a backup
              that can be restored later. Therefore, a fixed nam­
              ing  scheme is used (see below). Every modification
              creates a new backup. These will be  restored  cor­
              rectly even if it happens in another sequence. If a
              service crashes, there is a way to clean  up  stale
              modification and to restore the original configura­
              tion.

       - add an informational header
              to the new configuration file that informs the user
              (or  other  programs) that is was changed temporar­
              ily, who changed the file, why it was done and  how
              to avoid it in the future. This header is automati­
              cally created by modify_resolvconf and is therefore
              standardized.  It  is  just  the  presence  of this
              header what marks it as temporarily modified.

       - trigger needed actions
              like  restarting  named  if   /etc/named.conf   was
              changed  or  copy  a  modified  /etc/resolv.conf to
              postfix's chroot environment.

       It is recommended to  make  use  of  modify_resolvconf  in
       every    script    that   modifies   /etc/resolv.conf   or
       This naming scheme allows  restoring  /etc/resolv.conf  at
       boottime  after  a  crash of the system or at starttime of
       the service (after a crash of the service).

       modify_resolvconf can be controlled with two variables  in
       SuSE's     /etc/sysconfig/network/config.     With    MOD­
       IFY_RESOLV_CONF_DYNAMICALLY you can allow/disallow dynamic
       changes  to  /etc/resolv.conf. If you like /etc/named.conf
       to be modified instead, then set MODIFY_NAMED_CONF_DYNAMI­
       CALLY  to  yes. Since it makes not much sense to write the
       same nameservers to both  files  MODIFY_NAMED_CONF_DYNAMI­
       CALLY has a higher priority then MODIFY_RESOLV_CONF_DYNAM­
       ICALLY.

       Programs which use modify_resolvconf don't need to respect
       these  variables.  They should call modify_resolvconf just
       always.


ACTIONS

       modify write a  new  /etc/resolv.conf  or  /etc/named.conf
              with  the  supplied data and create a backup of the
              old one.

       restore
              take a backup of the given service (if  it  exists)
              and  restore it to the modified file. This might be
              /etc/resolv.conf  or  /etc/named.conf   itself   or
              another  backup  which  was  made in between by any
              other     service.     E.g.     pcmcia     modified
              /etc/resolv.conf  for  an  ethernet  interface  and
              after that ppp modifies it again for a  modem  con­
              nection. If you then eject the pcmcia card but keep
              the modem connection, the  backup  made  by  pcmcia
              will  be  restored  to  the  backup made by ppp and
              leave the /etc/resolv.conf or /etc/named.conf modi­
              fied by ppp untouched.
              If  no extension was given it will remove all other
              backups      of       the       given       service
              (resolv.conf.saved.by.<service>*).

       cleanup
              remove   all   backups   of   /etc/resolv.conf  and
              /etc/named.conf while trying to restore the  origi­
              nal  ones. It does so for both /etc/resolv.conf and
              /etc/named.conf independently of  the  settings  of
              the  variables in /etc/sysconfig/network/config. If
              you want to clean up only for one of these then use
              the --resolv or --named option.

       check  return  0 if /etc/resolv.conf has not been modified
              dynamically and write a status message  to  stderr.


OPTIONS

       -s, --service <service>
              name of the service that requests the modification.
              This will used for the name of the backup,  and  it
              is  put into the Modified_by tag of the info header
              (see example below).

       -e, --extension <string>
              appends an additional extension to the backup file­
              name  (this can be used by a service to create more
              than one backup like for different ppp devices)

       -p, --process <process>
              name of the daemon that causes the modification (if
              applicable)

       -i, --pid <pid>
              process  ID of the daemon that causes the modifica­
              tion (if applicable)

       -f, --script <filename>
              some script is used by the daemon  to  request  the
              modification

       -t, --text <text>
              a  text  written  to  the informational header that
              explains why the change was done and how to prevent
              it in the future. If - is given as <text>, the text
              is read from stdin.

       -l, --searchlist <list of search domains>
              specifies a list of domains,  separated  by  spaces
              and   protected   by   quotes,  to  be  written  to
              /etc/resolv.conf as searchlist

       -d, --domain <domainname>
              the domain to be used

       -n, --nameservers <list of nameservers>
              the (space separated and quoted if necessary)  list
              of nameservers to be used

       -o, --save_now <filename>
              saves       the       current      /etc/resolv.conf
              (/etc/named.conf) to the specified file.  This  may
              be  used  if you are interested in the modification
              after restore or cleanup. Alternatively you can use
              --save_later when modifying.

       -a, --save_later <filename>
              inserts  an  additional  tag into the informational
              header specifying a filename to use for  an  backup

       --named
              restores, cleans up or checks /etc/named.conf inde­
              pendently of  the  settings  of  the  variables  in
              /etc/sysconfig/network/config.   This  variable  is
              ignored with 'modify'.

       --no_restart
              does not trigger any actions like restarting  named
              or  copying /etc/resolv.conf to the chroot environ­
              ment of postfix.

       -v, --verbose
              be verbose

       -q, --quiet
              be quiet

       -h, --help
              show synopsis


EXAMPLE

       This is an example  for  the  /etc/resolv.conf  that  mod­
       ify_resolvconf would create:

       ### BEGIN INFO
       #
       # Modified_by:  dhcpcd
       # Backup:       /etc/resolv.conf.saved.by.dhclient
       # Process:      /sbin/dhcpcd
       # Process_id:   12345
       # Script:
       #
       # Info:         blabla
       #               ...
       #
       ### END INFO
       search suse.de
       nameserver 10.10.0.1
       nameserver 10.10.0.2


FILES

       /etc/resolv.conf
       /etc/named.conf


BUGS

       save_later   does  not  work  properly  if  restoring  one
       /etc/resolv.conf out of a stack of backups.
       Currently modify_resolvconf is dog slow, but this will  be
       enhanced in further versions.

  
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