Under Linux, how to execute the ifconfig command with regular expressions, only extract the IP address!

The method is too many, first simple to concise and gradual.

1.

[Email protected] ~]# ifconfig eth0|grep ' inet addr: ' # # #过滤不是IP地址的行

inet addr:192.168.16.100 bcast:192.168.16.255 mask:255.255.255.0

Or

[Email protected] ~]# ifconfig eth0|sed-n ' 2p ' # # #过滤不是IP地址的行

inet addr:192.168.16.100 bcast:192.168.16.255 mask:255.255.255.0

[Email protected] ~]# ifconfig eth0|sed-n ' 2p ' |sed-n ' s#^.*dr:# #gp '

192.168.16.100 bcast:192.168.16.255 mask:255.255.255.0 # # #已经去掉IP地址头部了.

[Email protected] ~]# ifconfig eth0|sed-n ' 2p ' |sed-n ' s#^.*dr:# #gp ' |sed-n ' s#b.*$# #gp '
# # #去掉IP地址尾巴.

192.168.16.100

2, using grep or sed &&cut combination extraction

Ifconfig eth0|grep "inet addr:" |cut-d ":"-f2|cut-d ""-f1

Ifconfig eth0|grep "inet addr:" |cut-f2-d ":" |cut-f1-d ""

Ifconfig eth0|grep "inet addr:" |cut-d:-f2|cut-d ""-f1

Ifconfig eth0|sed-n ' 2p ' |cut-c21-35

3. Use grep or sed &&awk to extract

ifconfig eth0|grep "inet addr" |awk-f ' [:]+ ' {print $4} '

Ifconfig eth0|sed-n '/inet addr/p ' |awk-f ' [:]+ ' {print $4} '

4, directly using SED regular expression to match

ifconfig eth0|sed-rn ' S#^.*DR: (. *) B.*$#\1#GP '

Ifconfig eth0|sed-n ' s#^.*dr:\ (. *\) B.*$#\1#GP '

5. Match with awk regular expressions directly

Ifconfig eth0|awk-f ' [:]+ ' nr==2 {print $4} '

ifconfig eth0|awk-f ' [:]+ '/bcast/{print $4} '

Ifconfig eth0|awk-f ' [:]+ '/inet addr:/ {Print $4} '

Ifconfig eth0|awk-f ' [:]+ ' $ $ ~ ' inet addr ' {print $4} '

6, directly with the grep regular expression to match the IP address number

Ifconfig eth0|grep-o ' \ ([1-9]\{1,3\}\.\) \{3\}[0-4]\{3,\} '

#####[0-4] do not exceed 4 otherwise the subnet mask will be extracted.

7.

IP Addr|grep-po ' [^]+ (? =/\d) ' |sed-n ' 3p '

8. Direct extraction of IP address files.

/etc/sysconfig/network-scripts/Ifcfg-eth0

Cat/etc/sysconfig/network-scripts/ifcfg-eth0|sed-n ' 10p ' |cut-d "="-f2

Under Linux, how to execute the ifconfig command with regular expressions, only extract the IP address!