On Apache
Under GNU General Public License
2024-05-23 08:02 @18.223.206.204 CrawledBy Mozilla/5.0 AppleWebKit/537.36 (KHTML, like Gecko; compatible; ClaudeBot/1.0; +claudebot@anthropic.com)
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] [--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) net-
work interfaces based on interface definitions in the file /etc/network/interfaces. if-
query 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.
--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. 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 ex-
its 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 in-
terfaces 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 sta-
tus 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 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 if-
plugd(8).
AUTHORS
The ifupdown suite was created by Anthony Towns <aj AT azure.au>, and is currently
maintained by Guus Sliepen <guus AT debian.org>.
Many others have helped develop ifupdown over time, see /usr/share/doc/ifup-
down/changelog.Debian.gz for a full history.
SEE ALSO
interfaces(5), ip(8), ifconfig(8).
IFUPDOWN 11 Jan 2017 ifup(8)
Generated by $Id: phpMan.php,v 4.55 2007/09/05 04:42:51 chedong Exp $ Author: Che Dong
On Apache
Under GNU General Public License
2024-05-23 08:02 @18.223.206.204 CrawledBy Mozilla/5.0 AppleWebKit/537.36 (KHTML, like Gecko; compatible; ClaudeBot/1.0; +claudebot@anthropic.com)