ifquery <root
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|--interfaces=FILE] [--allow CLASS]
       -a|IFACE...

       ifquery --state [IFACE...]

DESCRIPTION
       The ifup and ifdown commands may be used to configure (or, respectively, deconfigure) net‐
       work  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/net‐
              work/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.

       -X PATTERN, --exclude=PATTERN
              Exclude interfaces from the list of interfaces to operate on by the PATTERN.   PAT‐
              TERN 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 inter‐
              face  (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 inter‐
       faces.  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 configu‐
       ration 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 .

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

IFUPDOWN                                   23 May 2014                                    ifup(8)

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