* - matches all of the content information
[Application Scene One: Find data] when the Find / Oldboy -name "* .txt" the Find / -name Oldboy "Oldboy *" the Find / -name Oldboy "Oldboy * .txt " [application scene 2: operations Manager data] LL / Oldboy / Oldboy * RM -rf / Oldboy / * cp -a / Oldboy / * / tmp / RM / Oldboy / * -> cd / Oldboy RM -rf / * {} - matching the content information sequence {01..100} {a..z} {A..Z } {a scenario: generating a sequence of information] echo {01..10} --- generate a continuous sequence of echo {01..10..2} --- generate arithmetic sequence [the root @ localhost ~] # echo {A..Z} A B C D E F G H I J K L m n-O P Q R & lt S T U V W X Y Z [the root @ localhost ~] # echo {a..z..2} A C E G I K m O Q S U W Y [root @ localhost ~] # echo {01,03,07,08,09}
0103070809
Application Scene 2: sequence generating composition echo {01..03} {} A..C 01A 01B 01C 02A 02B 02C 03A 03B 03C echo {A, B} -> A AB echo oldboy.txt { , .bak} -> oldboy.txt oldboy.txt.bak CP /etc/selinux/config{,.bak} --- fast data backup method of echo B {A,} -> A AB echo oldboy.txt { .bak,} -> oldboy.txt.bak oldboy.txt CP oldboy.txt .bak {,} --- quick restore method
Regular expressions:
text-matching mode processing a large number of string
Note:
a.linux regular expression can be processed in units
b.alias grep = 'grep --color = auto ', so that the contents match the display color
c attention. character set. C = the LC_ALL Export
[the root @ localhost ~] # Export the LC_ALL = C
[the root @ localhost ~] $ # echo the LC_ALL
C
- [BRE] regular basis
locator tip: while anchoring the beginning and end, do an exact match; a single anchor the beginning and end, do fuzzy matching.
定位符 说明
^ 锚定开头 ^a 以a开头 默认锚定一个字符
$ 锚定结尾 a$ 以a结尾 默认锚定一个字符
找出文件/etc/service 以s开头的信息
找出/oldboy目录中 文件内容是oldboy开头的文件
老三: grep
grep "^s" /etc/services
[root@localhost oldboy]# grep -r "^oldboy" /oldboy
/oldboy/oldboy.txt:oldboy
/oldboy/oldbaby.txt:oldboy01
/oldboy/oldboy01/oldboy.txt:oldboy
/oldboy/oldboy01/oldbaby.txt:oldboy01
老二: sed
sed -n '/^s/p' /etc/services
老大: awk
awk '/^s/' /etc/services
. --- 匹配任意一个且只有一个字符信息
* --- 匹配星号字符前面的一个字符 连续出现0次或者多次的情况
.* --- 匹配所有内容信息
正则符号匹配字符信息时,有贪婪匹配特性
1) 将有特殊意义的符号变得没有意义
2) 将没有页数意义的字符变得有意义
\n --- 换行字符
\r --- 换行字符
\t --- 制表符
3) 取消别名功能
\rm -rf /oldboy.txt
二、特殊字符
匹配符:匹配字符串，包括普通字符（例如，a 到 z 之间的字母）和特殊字符（称为"元字符"）。它是一种字符串匹配的模式，可以用来检查一个字符串是否含有某种子串、
将匹配的子串替换或者从某个字符串中取出某个条件的子串
[ ] ---------定义字符类，匹配括号中的一个字符
[abc]: 匹配字符集合内的任意一个字符[a-z,A-Z],[0-9]等
匹配出文件中所有的字母信息（大小写问题）
~~~测试文件中以I开头行和以m开头的行都找出来】
[^abc]：匹配不包含^后面的任意一个字符的内容
练习题: 去除文件中所有符号信息
grep "[^0-9a-Z]" oldboy.txt
【表示匹配不包含I， ^， o的信息】
[ ^ ] 表示否定括号中出现字符类中的字符,取反。
+ --- 匹配加号字符前面的一个字符 连续出现1次或者多次的情况