Sometimes you may want to know what the state of an Ethernet card is. But lets say you don't have root, to use tools like ethtool or mii-tool.

Heres a quick tip

grep ''  /sys/class/net/eth0/*
/sys/class/net/eth0/address:00:1b:21:6a:85:d6
/sys/class/net/eth0/addr_len:6
/sys/class/net/eth0/broadcast:ff:ff:ff:ff:ff:ff
/sys/class/net/eth0/carrier:1
/sys/class/net/eth0/dev_id:0x0
/sys/class/net/eth0/dormant:0
/sys/class/net/eth0/duplex:full
/sys/class/net/eth0/features:0xba9
/sys/class/net/eth0/flags:0x1003
/sys/class/net/eth0/ifindex:2
/sys/class/net/eth0/iflink:2
/sys/class/net/eth0/link_mode:0
/sys/class/net/eth0/mtu:1500
/sys/class/net/eth0/operstate:up
/sys/class/net/eth0/speed:100
/sys/class/net/eth0/tx_queue_len:1000
/sys/class/net/eth0/type:1
/sys/class/net/eth0/uevent:INTERFACE=eth0
/sys/class/net/eth0/uevent:IFINDEX=2

HTH

Brent