通配符與正則表達式
通配符
通配符是用來匹配文件名的（最起碼linux系統(tǒng)中是這樣的）麻裳。
image
正則表達式與通配符的區(qū)別
正則表達式用來在文件中匹配符合條件的字符串完丽，正則是包含匹配。grep、awk兵罢、sed等命令可以支持正則表達式。
以下是列出install.log中所包含字符串net的行：
[root@localhost ~]# grep net install.log -n
203:Installing net-tools-1.60-110.el6_2.x86_64
413:Installing net-snmp-libs-5.5-49.el6.x86_64
521:Installing python-netaddr-0.7.5-4.el6.noarch
867:Installing net-snmp-5.5-49.el6.x86_64
929:Installing system-config-network-tui-1.6.0.el6.2-1.el6.noarch
通配符用來匹配符合條件的文件名滓窍，通配符是完全匹配卖词。ls、find吏夯、cp這些命令不支持正則表達式此蜈，所以只能使用shell自己的通配符來進行匹配了即横。
[root@localhost ~]# ls
anaconda-ks.cfg Downloads Hello.sh Music rightfile testfile
Desktop error install.log Pictures Templates Videos
Documents errorfile install.log.syslog Public test
[root@localhost ~]# ls install.log
install.log
[root@localhost ~]# ls install
ls: cannot access install: No such file or directory
基礎(chǔ)正則表達式
image
“*”前一個字符匹配0次，或任意多次
[root@localhost ~]# vim test
[root@localhost ~]# cat test
a1
aa2
aaa3
aaaa4
aaaaa5
[root@localhost ~]# grep "a*" test #匹配所有內(nèi)容裆赵，包括空白行
a1
aa2
aaa3
aaaa4
aaaaa5
[root@localhost ~]# grep "aa*" test #匹配至少包含有一個a的行
a1
aa2
aaa3
aaaa4
aaaaa5
[root@localhost ~]# grep "aaa*" test #匹配最少包含兩個連續(xù)a的字符串
aa2
aaa3
aaaa4
aaaaa5
[root@localhost ~]# grep "aaaa*" test #匹配最少包含三個連續(xù)a的字符串
aaa3
aaaa4
aaaaa5
[root@localhost ~]# grep "aaaaa*" test #匹配最少包含四個連續(xù)a的字符串
aaaa4
aaaaa5
[root@localhost ~]# grep "aaaaaa*" test #匹配最少包含五個連續(xù)a的字符串
aaaaa5
“.” 匹配除了換行符外任意一個字符
[root@localhost ~]# vim test
[root@localhost ~]# cat test
a1
aa2
aaa3
aaaa4
aaaaa5
seed seeed s d
s!@#d s123d
sd
[root@localhost ~]# grep "s..d" test #“s..d”會匹配在s和d這兩個字母之間一定有兩個字符的內(nèi)容
seed seeed s d
[root@localhost ~]# grep "s.*d" test #匹配在s和d字母之間有任意字符
seed seeed s d
s!@#d s123d
sd
[root@localhost ~]# grep ".*" test #匹配所有內(nèi)容
a1
aa2
aaa3
aaaa4
aaaaa5
seed seeed s d
s!@#d s123d
sd
“^”匹配行首东囚，“$”匹配行尾
root@localhost ~]# grep "^a" test #匹配以字母"a"開頭的行
a1
aa2
aaa3
aaaa4
aaaaa5
[root@localhost ~]# grep "d$" test #匹配以字母"d"結(jié)尾的行
seed seeed s d
s!@#d s123d
sd
[root@localhost ~]# grep -n "^$" test #匹配空白行
4:
7:
“[]”匹配中括號中指定的任意一個字符，只匹配一個字符
[root@localhost ~]# vim test
[root@localhost ~]# cat test
a1
aa2
aaa3
aaaa4
aaaaa5
seed seeed s d
s!@#d s123d
sd
saoid
said
soid
s1d
s2d
ABS
Abb
1
2
7
8
24
91
[root@localhost ~]# grep "s[ao]id" test #匹配s和i字母中战授，要么是a页藻、要么是o
said
soid
[root@localhost ~]# grep "[0-9]" test #匹配任意一個數(shù)字
a1
aa2
aaa3
aaaa4
aaaaa5
s!@#d s123d
s1d
s2d
1
2
7
8
24
91
[root@localhost ~]# grep "^[a-z]" test #匹配以小寫字母開頭的行
a1
aa2
aaa3
aaaa4
aaaaa5
seed seeed s d
s!@#d s123d
sd
saoid
said
soid
s1d
s2d
[root@localhost ~]# grep "^[A-Z]" test #匹配以大寫字母開頭的行
ABS
Abb
“[^]”匹配除中括號的字符以外的任意一個字符
[root@localhost ~]# grep "^[^a-z]" test #匹配不以小寫字母開頭的行
ABS
Abb
1
2
7
8
24
91
[root@localhost ~]# grep "^[^a-zA-Z]" test #匹配不以字母開頭的行
1
2
7
8
24
91
“\” 轉(zhuǎn)義符
[root@localhost ~]# grep . test
a1
aa2
aaa3
aaaa4
aaaaa5
seed seeed s d
s!@#d s123d
sd
saoid
said
soid
s1d
s2d
ABS
Abb
1
2
7
8
24
91
[root@localhost ~]# vim test
[root@localhost ~]# cat test
a1
aa2
aaa3
aaaa4
aaaaa5
seed seeed s d.
s!@#d s123d.
sd.
saoid
said
soid
s1d
s2d
ABS
Abb
1
2
7
8
24
91
[root@localhost ~]# grep "\.$" test
seed seeed s d.
s!@#d s123d.
sd.
“\{n\}” 表示其前面的字符恰好出現(xiàn)n次
[root@localhost ~]# grep "a\{3\}" test #匹配a字母連續(xù)出現(xiàn)三次的字符串
aaa3
aaaa4
aaaaa5
[root@localhost ~]# grep "[0-9]\{2\}" test #匹配包含連續(xù)的兩個數(shù)字的字符串
s!@#d s123d.
24
91
“\{n,\}”表示其前面的字符出現(xiàn)不小于n次
[root@localhost ~]# vim test
[root@localhost ~]# cat test
the a1
the aa2
the aaa3
the aaaa4
the aaaaa5
google
gooogle
goooogle
oogle
ooogle
oooogle
12saoid
123said
1234soid
12345s1d
[root@localhost ~]# grep "^[0-9]\{3,\}[a-z]" test #匹配至少以連續(xù)三個數(shù)字開頭的行
123said
1234soid
12345s1d
[root@localhost ~]# grep "^[0-9]\{4,\}[a-z]" test #匹配至少以連續(xù)四個數(shù)字開頭的行
1234soid
12345s1d
“\{n,m\}”匹配其前面的字符至少出現(xiàn)n次，最多出現(xiàn)m次陈醒。
[root@localhost ~]# vim test
[root@localhost ~]# cat test
the a1
the aa2
the aaa3
the aaaa4
the aaaaa5
google
gooogle
goooogle
oogle
ooogle
oooogle
abc
abbc
abbbc
adc
addc
ac
[root@localhost ~]# grep "ab\{1,3\}c" test #匹配在字母a和c
abc
abbc
abbbc
反向選擇
[root@localhost ~]# grep -vn "the" test
#取不以“the”開頭的行并顯示行號
6:
7:google
8:gooogle
9:goooogle
10:oogle
11:ooogle
12:oooogle
13:
14:abc
15:abbc
16:abbbc
17:adc
18:addc
19:ac
[root@localhost ~]# grep -v "the" test
#取不以“the”開頭的行
google
gooogle
goooogle
oogle
ooogle
oooogle
abc
abbc
abbbc
adc
addc
ac
