*BASH User Commands Ubuntu 10.04.4 LTS Server coreutils
ifup(8)                                                                ifup(8)

       ifup - bring a network interface up

       ifdown - take a network interface down

       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...

       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.

       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.  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 configuration or deconfiguration of the interface.

       -h, --help
              Show summary of options.

              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-

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

              Don't  run any mappings.  See interfaces(5) for more information
              about the mapping feature.

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

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

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

       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.

       ifup  and  ifdown  are  actually  the  same program called by different

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

              definitions  of  network  interfaces  See interfaces(5) for more

              current state of network interfaces

       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 /var/run/network/ifstate must be writable for ifup  or  ifdown
       to  work  properly.   On  Ubuntu  the  /var/run location is a temporary
       filesystem which is always writable and thrown away on  shutdown.   You
       can also 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  hot-
       plug(8) or ifplugd(8).

       The   ifupdown  suite  was  written  by  Anthony  Towns  <aj@azure.hum-

       interfaces(5), ifconfig(8).

IFUPDOWN                          22 May 2004                          ifup(8)