# 17 个案例带你 5 分钟搞定 Linux 正则表达式

1. Shell元字符，由Linux Shell进行解析；

2. 正则表达式元字符，由vi/grep/sed/awk等文本处理工具进行解析；

$alias grep='grep --color=auto' 这样每次过滤出来的字符串都会带色彩了。 在开始之前还需要做一件事情，就是创建一个测试用的re-file文件，内容如下： $ 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.

• 特殊的元字符

• 扩展的正则表达式

### 实操

• 匹配以love开头的所有行

$grep '^love' re-file love, how much I adore you. Do you know • 匹配love结尾的所有行 $ 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 $ 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

$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 $ 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

$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 $ 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.

$grep 'love\.' re-file clover. Did you see them? I can only hope love. • 匹配空格 $ grep '^$' re-file • 匹配任意字符 $ 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

$grep 'o\{2,4\}' re-file groove. • 重复o字符至少2次 $ grep 'o\{2,\}' re-file
groove.
• 重复0字符最多2次

$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 $ egrep "go+d" linux.txt
Linux is a good
god assdxw bcvnbvbjk
gooodfs awrerdxxhkl
good
• 0个或者一个字符

ansheng@Ubuntu:/tmp$egrep "go?d" linux.txt god assdxw bcvnbvbjk gdsystem awxxxx • 或，查找多个字符串 $ egrep "gd|good" linux.txt
Linux is a good
gdsystem awxxxx
good
• 分组过滤匹配

\$ egrep "g(la|oo)d" linux.txt
Linux is a good
glad
good

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