ifup(8)                   (11 Jan 2017)                   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] [--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] [--verbose] [-i FILE|--interfaces=FILE]
          [--state-dir=DIR] [--allow CLASS] IFACE...

          ifquery -l|--list [-nv] [--verbose] [-i
          FILE|--interfaces=FILE] [--state-dir=DIR] [--allow CLASS]
          [-a|IFACE...]

          ifquery --state [--state-dir=DIR] [--allow CLASS]
          [-a|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 inter-
               faces.  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

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               Force configuration or deconfiguration of the inter-
               face.

          --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.

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

          -X PATTERN, --exclude=PATTERN
               Exclude interfaces from the list of interfaces to oper-
               ate 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 prede-
               fined 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 config-
               ured 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

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               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 ifup-
               down configuration. Each key-value pair is printed out
               on individual line using ": " as separator.

     NOTES
          ifup, ifdown, and ifquery are actually the same program

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          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

     CONCURRENCY
          Ifupdown uses per-interface locking to ensure that concur-
          rent ifup and ifdown calls to the same interface are run in
          serial.  However, calls to different interfaces will be able
          to run in parallel.

     EXIT STATUS
          For ifup and ifdown, the exit status will be 0 if the given
          interface(s) have all been (de)configured successfully, 1 if
          there was any error.  The result of these commands is idem-
          potent; running ifup on an interface that is already up will
          result in an exit status of 0, and similarly running ifdown
          on an interface that is not up will also result in an exit
          status of 0.

          ifquery will normally return with exit status 0 if an inter-
          face with a matching iface stanza, 1 if there is no matching
          stanza.  ifquery --state will also return with exit status 1
          if the given interface was known but was not up.

     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 deconfigura-
          tion 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

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          (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 con-
          figuration 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 inter-
          faces you need to install other packages such as udev(7) or
          ifplugd(8).

     AUTHORS
          The ifupdown suite was created by Anthony Towns
          <aj@azure.humbug.org.au>, currently maintained by Santiago
          Ruano Rincón <santiago@debian.org> and Josue Ortega
          <josue@debian.org>

          Many others have helped develop ifupdown over time, see
          /usr/share/doc/ifupdown/changelog.Debian.gz for a full his-
          tory.

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

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