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ifup(8)								       ifup(8)

NAME
       ifup - bring a network interface up

       ifdown - take a network interface down

       ifquery - parse interface configuration

SYNOPSIS
       ifup  [-nv] [--no-act] [--verbose] [-i FILE|--interfaces=FILE] [--allow
       CLASS] -a|IFACE...
       ifup -h|--help
       ifup -V|--version

       ifdown  [-nv]  [--no-act]   [--verbose]	 [-i   FILE|--interfaces=FILE]
       [--allow CLASS] -a|IFACE...

       ifquery	 [-nv]	 [--no-act]  [--verbose]  [-i  FILE|--interfaces=FILE]
       [--allow CLASS] -a|IFACE...

       ifquery	-l|--list  [-nv]  [--no-act]  [--verbose]  [-i	 FILE|--inter‐
       faces=FILE] [--allow CLASS] -a|IFACE...

       ifquery --state [IFACE...]

DESCRIPTION
       The  ifup  and  ifdown  commands	 may be used to configure (or, respec‐
       tively, deconfigure) network interfaces based on interface  definitions
       in  the	file  /etc/network/interfaces.	ifquery command may be used to
       parse interfaces configuration.

OPTIONS
       A summary of options is included below.

       -a, --all
	      If given to ifup, affect all interfaces marked auto.  Interfaces
	      are  brought  up	in  the	 order	in  which  they are defined in
	      /etc/network/interfaces.	Combined with  --allow,	 acts  on  all
	      interfaces  of  a	 specified class instead.  If given to ifdown,
	      affect all defined interfaces.  Interfaces are brought  down  in
	      the  order in which they are currently listed in the state file.
	      Only  interfaces	defined	 in  /etc/network/interfaces  will  be
	      brought down.

       --force
	      Force configuration or deconfiguration of the interface.

       -h, --help
	      Show summary of options.

       --allow=CLASS
	      Only allow interfaces listed in an allow-CLASS line in /etc/net‐
	      work/interfaces to be acted upon.

       -i FILE, --interfaces=FILE
	      Read interface definitions from FILE instead of  from  /etc/net‐
	      work/interfaces.

       -X PATTERN, --exclude=PATTERN
	      Exclude  interfaces from the list of interfaces to operate on by
	      the PATTERN.  PATTERN uses a usual shell glob syntax.  If	 shell
	      wildcards	 are not used, it must match the exact interface name.
	      This option may be specified multiple times  resulting  in  more
	      than one pattern being excluded.

       -o OPTION=VALUE
	      Set  OPTION  to  VALUE  as though it were in /etc/network/inter‐
	      faces.

       -n, --no-act
	      Don't configure any interfaces or run any "up"  or  "down"  com‐
	      mands.

       --no-mappings
	      Don't  run any mappings.	See interfaces(5) for more information
	      about the mapping feature.

       --no-scripts
	      Don't run any scripts under /etc/network/if-*.d/

       --no-loopback
	      Disable special handling of the loopback interface. By  default,
	      the loopback interface (lo on Linux) is predefined internally as
	      an auto interface, so it's brought up on ifup -a	automatically.
	      In the case the loopback device is redefined by user, the inter‐
	      face is configured just once anyway. If, however, another inter‐
	      face  is	also  defined  as  loopback, it's configured as usual.
	      Specifying this option disables this behaviour, so the  loopback
	      interface won't be configured automatically.

       -V, --version
	      Show copyright and version information.

       -v, --verbose
	      Show commands as they are executed.

       -l, --list
	      For  ifquery,  list all the interfaces which match the specified
	      class.  If no class specified, prints all the interfaces	listed
	      as auto.

       --state
	      For  ifquery,  dump  the state of the interfaces. When no inter‐
	      faces specified, lists all interfaces brought up	together  with
	      logical interfaces assigned to them and exits with a status code
	      indicating success. If one or more interfaces specified, display
	      state  of	 these interfaces only; successful code is returned if
	      all of interfaces given as arguments are	up.  Otherwise,	 0  is
	      returned.

EXAMPLES
       ifup -a
	      Bring  up	 all  the  interfaces  defined	with auto in /etc/net‐
	      work/interfaces

       ifup eth0
	      Bring up interface eth0

       ifup eth0=home
	      Bring up interface eth0 as logical interface home

       ifdown -a
	      Bring down all interfaces that are currently up.

       ifquery -l
	      Print names of all interfaces specified with the auto keyword.

       ifquery -l --allow=hotplug
	      Print names of all interfaces specified with  the	 allow-hotplug
	      keyword.

       ifquery eth0
	      Display  the interface options as specified in the ifupdown con‐
	      figuration. Each key-value pair is  printed  out	on  individual
	      line using ": " as separator.

NOTES
       ifup,  ifdown, and ifquery are actually the same program called by dif‐
       ferent names.

       The program does not configure network interfaces directly; it runs low
       level utilities such as ip to do its dirty work.

       When  invoked,  ifdown  checks  if ifup is still running. In that case,
       SIGTERM is sent to ifup.

FILES
       /etc/network/interfaces
	      definitions of network interfaces	 See  interfaces(5)  for  more
	      information.

       /run/network/ifstate
	      current state of network interfaces

KNOWN BUGS/LIMITATIONS
       The program keeps records of whether network interfaces are up or down.
       Under exceptional circumstances these records can  become  inconsistent
       with the real states of the interfaces.	For example, an interface that
       was brought up using ifup and later deconfigured	 using	ifconfig  will
       still be recorded as up.	 To fix this you can use the --force option to
       force ifup or ifdown to run configuration or  deconfiguration  commands
       despite what it considers the current state of the interface to be.

       The  file  /run/network/ifstate	must be writable for ifup or ifdown to
       work properly.  If that location is not writable (for example,  because
       the  root  filesystem  is  mounted  read-only for system recovery) then
       /run/network/ifstate should be made a symbolic link to a writable loca‐
       tion.   If  that is not possible then you can use the --force option to
       run configuration or  deconfiguration  commands	without	 updating  the
       file.

       Note  that  the program does not run automatically: ifup alone does not
       bring up interfaces that appear as a result of hardware being installed
       and  ifdown  alone  does	 not bring down interfaces that disappear as a
       result of hardware being removed.  To  automate	the  configuration  of
       network	interfaces  you need to install other packages such as udev(7)
       or ifplugd(8).

AUTHOR
       The  ifupdown  suite  was  written  by  Anthony	Towns	<aj@azure.hum‐
       bug.org.au>.

SEE ALSO
       interfaces(5), ip(8), ifconfig(8).

IFUPDOWN			  22 May 2004			       ifup(8)
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