$ cat re-file I had a lovely time on our little picnic. Lovers were all around us. It is springtime. Oh love, how much I adore you. Do you know the extent of my love? Oh, by the way, I think I lost my gloves somewhere out in that field of clover. Did you see them? I can only hope love. is forever. I live for you. It's hard to get back in the groove.
文件内容摘录自<<UNIX/SHELL范例精解第四版>>
1 2 3 4 5 6 7 8 9
$ cat linux.txt Linux is a good god assdxw bcvnbvbjk greatttttt wexcvxc operaaaating dhfghfvx gooodfs awrerdxxhkl gdsystem awxxxx glad good
正则表达式元字符
元字符
功能
^
以什么开头
$
以什么结尾
.
匹配一个字符
*
匹配0个或多个
[]
匹配集合中的
[x-y]
匹配集合范围内的
[^ ]
匹配不在集合中的
\
转义
特殊的元字符
元字符
功能
实例
怎么匹配
<
以什么开头
‘<love’
匹配以love开头的所有行
>
以什么结尾
‘love>’
匹配love结尾的所有行
\(…\)
标签匹配以后使用的字符
‘(love)able \1er’
用位置\1\2引导前面做好的标签，最大支持9个
x\{m\} or x\{m,\} or x\{m,n\}
重复字符x，m次，至少m次，至少m且不超过n次
o\{5,10\}
o字符重复5到10次的行
扩展的正则表达式
元字符
说明
+
重复前一个字符一个或一个以上
?
0个或者一个字符
丨
表示或，查找多个字符串
（）
分组过滤匹配
实操
匹配以love开头的所有行
1 2
$ grep '^love' re-file love, how much I adore you. Do you know
匹配love结尾的所有行
1 2
$ grep 'love$' re-file clover. Did you see them? I can only hope love.
匹配以l开头，中间包含两个字符，结尾是e的所有行
1 2 3 4 5 6 7
$ grep 'l..e' re-file I had a lovely time on our little picnic. love, how much I adore you. Do you know the extent of my love? Oh, by the way, I think I lost my gloves somewhere out in that field of clover. Did you see them? I can only hope love. is forever. I live for you. It's hard to get back in the
匹配0个或多个空行，后面是love的字符
1 2 3 4 5 6
$ grep ' *love' re-file I had a lovely time on our little picnic. love, how much I adore you. Do you know the extent of my love? Oh, by the way, I think I lost my gloves somewhere out in that field of clover. Did you see them? I can only hope love.
匹配love或Love
1 2 3 4 5 6 7
$ grep '[Ll]ove' re-file # 对l不区分大小写 I had a lovely time on our little picnic. Lovers were all around us. It is springtime. Oh love, how much I adore you. Do you know the extent of my love? Oh, by the way, I think I lost my gloves somewhere out in that field of clover. Did you see them? I can only hope love.
匹配A-Z的字母，其次是ove
1 2
$ grep '[A-Z]ove' re-file Lovers were all around us. It is springtime. Oh
匹配不在A-Z范围内的任何字符行，所有的小写字符
1 2 3 4 5 6 7 8 9
$ grep '[^A-Z]' re-file I had a lovely time on our little picnic. Lovers were all around us. It is springtime. Oh love, how much I adore you. Do you know the extent of my love? Oh, by the way, I think I lost my gloves somewhere out in that field of clover. Did you see them? I can only hope love. is forever. I live for you. It's hard to get back in the groove.
匹配love.
1 2
$ grep 'love\.' re-file clover. Did you see them? I can only hope love.
匹配空格
1
$ grep '^$' re-file
匹配任意字符
1 2 3 4 5 6 7 8 9
$ grep '.*' re-file I had a lovely time on our little picnic. Lovers were all around us. It is springtime. Oh love, how much I adore you. Do you know the extent of my love? Oh, by the way, I think I lost my gloves somewhere out in that field of clover. Did you see them? I can only hope love. is forever. I live for you. It's hard to get back in the groove.
前面o字符重复2到4次
1 2
$ grep 'o\{2,4\}' re-file groove.
重复o字符至少2次
1 2
$ grep 'o\{2,\}' re-file groove.
重复0字符最多2次
1 2 3 4 5 6 7 8 9
$ grep 'o\{,2\}' re-file I had a lovely time on our little picnic. Lovers were all around us. It is springtime. Oh love, how much I adore you. Do you know the extent of my love? Oh, by the way, I think I lost my gloves somewhere out in that field of clover. Did you see them? I can only hope love. is forever. I live for you. It's hard to get back in the groove.
重复前一个字符一个或一个以
1 2 3 4 5
$ egrep "go+d" linux.txt Linux is a good god assdxw bcvnbvbjk gooodfs awrerdxxhkl good
0个或者一个字符
1 2 3
ansheng@Ubuntu:/tmp$ egrep "go?d" linux.txt god assdxw bcvnbvbjk gdsystem awxxxx
或，查找多个字符串
1 2 3 4
$ egrep "gd|good" linux.txt Linux is a good gdsystem awxxxx good
分组过滤匹配
1 2 3 4
$ egrep "g(la|oo)d" linux.txt Linux is a good glad good
