Provided by: ifupdown_0.8.17ubuntu1_amd64 bug

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] [--state-dir=DIR] [--allow
       CLASS] -a|IFACE...
       ifup -h|--help
       ifup -V|--version

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

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

       ifquery -l|--list  [-nv]  [--no-act]  [--verbose]  [-i  FILE|--interfaces=FILE]  [--state-
       dir=DIR] [--allow CLASS] -a|IFACE...

       ifquery --state [IFACE...]

DESCRIPTION

       The  ifup  and  ifdown  commands  may be used to configure (or, respectively, 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.

       --ignore-errors
              If any of the commands of scripts fails, continue.

       -h, --help
              Show summary of options.

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

       -i FILE, --interfaces=FILE
              Read interface definitions from FILE instead of from /etc/network/interfaces.

       --interfaces=DIR
              Keep interface state in DIR instead of in /run/network.

       -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/interfaces.

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

       --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 interface  is  configured  just  once  anyway.  If,  however,  another
              interface  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 interfaces 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/network/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 configuration. 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 different 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.

       During interface deconfiguration, ifdown ignores errors the same way as if --ignore-errors
       was specified.

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 location.  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.humbug.org.au>.

SEE ALSO

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