focal (8) ifup.8.gz

Provided by: ifupdown_0.8.35ubuntu1_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] [--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 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.

       --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 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

CONCURRENCY

       Ifupdown uses per-interface locking to ensure that concurrent 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 idempotent; 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 interface 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 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).

AUTHORS

       The  ifupdown suite was created by Anthony Towns <aj@azure.humbug.org.au>, and is currently maintained by
       Guus Sliepen <guus@debian.org>.

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

SEE ALSO

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