ifconfig eth0 取行取列

[root@xusx xusx]# ifconfig eth0
eth0      Link encap:Ethernet HWaddr 00:0C:29:9A:CD:B1
          inet addr:192.168.138.138 Bcast:192.168.138.255 Mask:255.255.255.0
          inet6 addr: fe80::20c:29ff:fe9a:cdb1/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
          RX packets:68094 errors:0 dropped:0 overruns:0 frame:0
          TX packets:41042 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:28601665 (27.2 MiB) TX bytes:5618664 (5.3 MiB)

第一种

[root@xusx ~]# ifconfig eth0|awk -F "[: ]+" 'NR==2{print $4}'
192.168.138.138

第二种

[root@xusx ~]# ifconfig eth0|sed -n '2p'|sed -r 's#(^.*r:)|(Bc.*$)##g'
192.168.138.138

[root@xusx ~]# ifconfig eth0|sed -nr '2s#^.*r:| Bc.*$##gp'
192.168.138.138

第三种

[root@xusx ~]# ifconfig eth0|egrep -o "inet addr:[0-9.]*"
inet addr:192.168.138.138
[root@xusx ~]# ifconfig eth0|egrep -o "inet addr:[0-9.]*"|egrep -o "[0-9.]*"
192.168.138.138

第四种