ifup - Man Page

• Enable interface eth0: ifup eth0
• Enable all the interfaces defined with "auto" in /etc/network/interfaces: ifup -a

tldr.sh

ifup — bring a network interface up

ifdown — take a network interface down

ifup CONFIG [boot]
ifdown CONFIG

The ifup and ifdown commands may be used to configure (or, respec- tively, deconfigure) network interfaces based on interface definitions in the files /etc/sysconfig/network and /etc/sysconfig/network-scripts/ifcfg-<configuration>

These scripts take one argument normally: the name of the configuration (e.g. eth0). They are called with a second argument of "boot" during the boot sequence so that devices that are not meant to be brought up on boot (ONBOOT=no, see below) can be ignored at that time.

/etc/sysconfig/network

/etc/sysconfig/network-scripts/ifcfg-<configuration>

The file defining an interface.

/usr/share/doc/initscripts-*/sysconfig.txt