Portable way to get list of all active network interfaces
I would like to get the list of all active network interfaces (e.g. eth0, wlan0). I assume I'll have to parse the output of ifconfig, but the formatting is different across the various OS's. Does anybody have a portable way to get this information so it can be used on the majority of unices (linux, *bsd, mac).
Not sure about portabilty because a list of network interfaces may be related to the kernel implementation and linux is not related at all to *bsd/mac... however if ifconfig is not good for you you can try netstat -i
Check out the facter package. It is used mostly by the puppet config management program to grab metadata from installed machines, but it can be run in a standalone fashion for similar purposes. Its output does include information about network interfaces found on the machine, and its formatting will be consistent across platforms.
Example output:
user@host:~$ facter
architecture => i386
domain => members.linode.com
facterversion => 1.3.8
fqdn => host.members.linode.com
hardwareisa => unknown
hardwaremodel => i686
hostname => host
id => user
ipaddress => 1.2.3.4
ipaddress_eth0 => 1.2.3.4
kernel => Linux
kernelrelease => 2.6.32.16-linode28
lsbdistcodename => hardy
lsbdistdescription => Ubuntu 8.04.4 LTS
lsbdistid => Ubuntu
lsbdistrelease => 8.04
macaddress => 76:c9:3e:0b:xx:xx
macaddress_eth0 => fe:fd:43:12:xx:xx
memoryfree => 393.08 MB
memorysize => 498.68 MB
operatingsystem => Debian
operatingsystemrelease => 2.6.32.16-linode28
processor0 => Intel(R) Xeon(R) CPU L5335 @ 2.00GHz
processor1 => Intel(R) Xeon(R) CPU L5335 @ 2.00GHz
processor2 => Intel(R) Xeon(R) CPU L5335 @ 2.00GHz
processor3 => Intel(R) Xeon(R) CPU L5335 @ 2.00GHz
processorcount => 4
ps => ps -ef
rubysitedir => /usr/local/lib/site_ruby/1.8
rubyversion => 1.8.6
swapfree => 186.84 MB
swapsize => 255.99 MB
uniqueid => 007f0101
The following will return a list of active interfaces on all the common Linux distros:
ifconfig | grep "Link encap" | awk '{ print $1 '}
If you want to also include interfaces which are currently down (inactive), simply add the -a flag as follows:
ifconfig -a | grep "Link encap" | awk '{ print $1 '}
As far as I know, there is no common method which can be used on any POSIX system to retrieve a list of network interfaces, so you'll have to localize your command for the OS currently in use.