提取邮箱和URL
[root@test88 ~]# cat url_email.txt
root@gmail.com,http://blog.peter.com,peter@qq.com
[root@test88 ~]# egrep -o '[A-Za-z0-9._]+@[A-Za-z0-9.]+\.[A-Za-z]{2,4}' url_email.txt
root@gmail.com
peter@qq.com
[root@test88 ~]# egrep -o "http://[A-Za-z0-9.]+\.[A-Za-z]{2,4}" url_email.txt
http://blog.peter.com
常用选项整理
grep -v 排除内容
grep -B 显示匹配行和之前num行
grep -A 显示匹配行和之后num行
grep -C 显示匹配行和前后num行
grep --color=auto 匹配字符串加色显示
grep -n 打印行号
grep -i 不区分大小写
grep -w 匹配单词
grep -E 即egrep使用扩展正则表达式
grep -e 匹配多个模式
grep -c 匹配到的行数
[root@test88 ~]# cat test.txt
one
two
three
four
five
ONE
TWO
THREE
FOUR
FIVE
#grep -v 取反
[root@test88 ~]# grep -v t test.txt
one
four
five
#grep -n 行号
[root@test88 ~]# grep -n t test.txt
2:two
3:three
#grep -c 行数
[root@test88 ~]# grep -c t test.txt
2
#grep -i 不区分大小写
[root@test88 ~]# grep -i t test.txt
two
three
TWO
THREE
#grep -e 匹配多个模式
[root@test88 ~]# grep -e t -e f test.txt
two
three
four
five
#grep -B 匹配行和前面n行
[root@test88 ~]# grep -n four -B 3 test.txt
1-one
2-two
3-three
4:four
#grep -A 匹配行和后面n行
[root@test88 ~]# grep -n one -A 3 test.txt
1:one
2-two
3-three
4-four
#grep -C 匹配行和前后n行
[root@test88 ~]# grep -n two -C 1 test.txt
1-one
2:two
3-three
#grep -w 匹配单词
[root@test88 ~]# grep -w two test.txt
two
#grep -E 使用扩展正则表达式，等同egrep
[root@test88 ~]# grep -E "t|f" test.txt
two
three
four
five
