Linux学习之shell 编程基础（一）

程序员文章站 2022-06-24 20:31:33

...

一、linux中经常和正则表达式联合使用的工具

grep

sed

awk（自己去研究吧）.

二，以grep为例，有以下正则操作

**特殊符号汇总**
特殊符号	代表意义
[:alnum:]	代表英文大小写字符及数字，亦0-9，A-Z，a-z
[:alpha:]	代表任何英文大小写字符，亦A-Z，a-z
[:blank:]	代表空格键与[Tab]按键两者
[:cntrl:]	代表键盘上面的控制按键，亦即包括CR、LF、Tab、Del..等等
[:digit:]	代表数字而已，亦即0-9
[:graph:]	除了空格符（空格键与[Tab]按键）外的其他所有按键
[:lower:]	代表小写字符，亦即a-z
[:print:]	代表任何可以被打印出来的字符
[:punct:]	代表标点符号（punctuation,symbol),亦即A：" ' ?!;:#$...
[:upper:]	代表大写字符，亦即A-Z
[:space:]	任何会产生空白的字符，包括空格键，[Tab],CR等等
[:xdigit:]	代表16进位的数字类型，因此包括：0-9,A-F,a-f的数字与字符

**基础正则表示法字符汇总**
RE字符	意义与范例
^word	意义：待搜寻的字符串（word）在行首！范例：搜寻行首为#开始的那一行，并列出行号 grep -n '^#' regular_express.txt
word$	意义：带搜寻的字符串（word）在行尾！范例：将行尾为！的那一行打印出来，并列出行号 grep -n '!$' regular_express.txt
.	意义：代表一定有一个任意字符的字符！范例：搜寻的字符串可以是(eve) (eae) (eee) (e e),但不能仅有(ee) ! 亦即e与e中间一定仅有一个字符，而空格符也是字符！ grep -n 'e.e' reg
\	意义：跳脱字符，将特殊符号的特殊意义去除！范例：搜寻含有单引号'的那一行！ grep -n \' regular_express.txt
*	意义：重复零个到无穷多个的前一个RE字符范例：找出含有(es)(ess)(esss)等等的字符串，注意，因为可以是0个，所以es也是符合待搜寻字符串。另外，因为为重复前一个RE字符的符号，因此，在之前必须要紧接着一个RE字符喔！例如任意字符则为 .
[list]	意义：字符集合的RE字符，里面列出想要的字符！范例：搜寻含有(gl)或(gd)的那一行，需要特别留意的是，在[]当中仅代表一个待搜寻的字符，例如a[afl]y代表搜寻的字符串可以是aay,afy,aly即[afl]代表a或f或l的意思！ grep -n 'g[ld]' regular_express.txt
[n1-n2]	意义：字符集合的RE字符，里面列出想要获取的字符范围！范例：搜寻含有任意数字的那一行！需特别留意，在字符集合[]中的减号 - 是有特殊意义的，他代表两个字符之间的所有连续字符！但这个连续与否与ASCII编码有关，因此，你的编码需要设定正确（在bash当中，需要确定LANG与LANGUAGE的变量是否正确！）例如所有大写字符则为[A-Z] grep -n '[0-9]' regular_express.txt 或 grep -n '[[:digit:]]' regular_express.txt
[^list]	意义：字符集合的RE字符，里面列出不要的字符串或范围！范例：搜寻的字符串可以是(oog) (ood) 但不能是(oot),那个^在[]内时，代表的意义是反向选择的意思。例如，我不要大写字符，则为[^A-Z]。但是，需要特别注意的是，如果以grep -n [^A-Z] regular_express.txt 来搜寻，却发现该档案内的所有行都被列出，为什么？因为这个[^A-Z]是非大写字符的意思，因为每一行均有非大写字符，例如第一行的"Open Source" 就有p,e,n,o...等等的小写字 grep -n 'oo[^t]' regular_express.txt
\{n,m\}	意义：连续n到m个的前一个RE字符意义：若为\{n\}则是连续n个的前一个RE字符。意义：若是\{n,\}则是连续n个以上的前一个RE字符！范例：在g与g之间有2个到3个的o存在的字符串，亦即（goog）(gooog) grep -n 'go\{2,3\}g' regular_express.txt

延伸型正则表达式字符
RE字符	意义与范例
+	意义：重复一个或一个以上的前一个RE字符范例：搜寻(god)(good)(goood)...等等的字符串。那个o+代表一个以上o，所以，底下的执行成果会将1，9，13行列出来。 egrep -n 'go+d' regular_express.txt
？	意义：零个或一个的前一个RE字符范例：搜寻(gd)(god)这两个字符串。那个o?代表空的或1个o，所以，上面的执行成果会将第13，14行列出来。有没有发现到，这两个案例('go+d'与’go?d')的结果集合与'go*d'相同？想想看，为啥呢 egrep -n 'go?d' regular_express.txt
\|	意义：用或(or)的方法找出数个字符串范例：搜寻gd或good这两个字符串，注意，是或！所以，第1，9，14这三行都可以被打印出来，那如果还想找出dog呢？ egrep -n 'gd\|good' regular_express.txt egrep -n 'gd\|good\|dog' regular_express.txt
()	意义：找出群组字符串范例：搜寻(glad)或(good)这两个字符串，因为g与d是重复的，所以，我就可以将la与oo列于()当中，并以\|来分隔开来，就可以啦！ egrep -n 'g(la\|oo)d' regular_express.txt
()+	意义：多个重复群组的判别范例：将AxyzxyzxyzxyzC 用echo叫出，然后再使用如下的方法搜寻一下！ echo 'AxyzxyzxyzC'\|egrep 'A(xyz)+C' 上面的例子意思是说，我要找开头是A结尾是C，中间有一个以上的'xyz'字符串的意思。

三、sed工具

1) 以行为单位的新增/删除功能

删除2-5行

[[email protected] ~]$ nl regular_express.txt |sed '2,5d'
     1	"Open Source" is a good mechanism to develop programs.
     6	GNU is free air not free beer.
     7	Her hair is very beauty.
     8	I can't finish the test.
     9	Oh! The soup taste good.
    10	motorcycle is cheap than car.
    11	This window is clear.
    12	the symbol '*' is represented as start.
    13	Oh!	My god!
    14	The gd software is a library for drafting programs.
    15	You are the best is mean you are the no. 1.
    16	The world <Happy> is the same with "glad".
    17	I like dog.
    18	google is the best tools for search keyword.
    19	goooooogle yes!
    20	go! go! Let's go.
    21	# I am VBird

删除第6行

[[email protected] ~]$ nl regular_express.txt |sed '6d'
     1	"Open Source" is a good mechanism to develop programs.
     2	apple is my favorite food.
     3	Football game is not use feet only.
     4	this dress doesn't fit me.
     5	However, this dress is about $ 3183 dollars.
     7	Her hair is very beauty.
     8	I can't finish the test.
     9	Oh! The soup taste good.
    10	motorcycle is cheap than car.
    11	This window is clear.
    12	the symbol '*' is represented as start.
    13	Oh!	My god!
    14	The gd software is a library for drafting programs.
    15	You are the best is mean you are the no. 1.
    16	The world <Happy> is the same with "glad".
    17	I like dog.
    18	google is the best tools for search keyword.
    19	goooooogle yes!
    20	go! go! Let's go.
    21	# I am VBird

删除第6行到最后一行

[[email protected] ~]$ nl regular_express.txt |sed '6,$d'
     1	"Open Source" is a good mechanism to develop programs.
     2	apple is my favorite food.
     3	Football game is not use feet only.
     4	this dress doesn't fit me.
     5	However, this dress is about $ 3183 dollars.

在第二行后（亦即是加在第三行）加上dalianmao字样

[[email protected] ~]$ nl regular_express.txt |sed '2a dalianmao'
     1	"Open Source" is a good mechanism to develop programs.
     2	apple is my favorite food.
dalianmao
     3	Football game is not use feet only.
     4	this dress doesn't fit me.
     5	However, this dress is about $ 3183 dollars.
     6	GNU is free air not free beer.
     7	Her hair is very beauty.
     8	I can't finish the test.
     9	Oh! The soup taste good.
    10	motorcycle is cheap than car.
    11	This window is clear.
    12	the symbol '*' is represented as start.
    13	Oh!	My god!
    14	The gd software is a library for drafting programs.
    15	You are the best is mean you are the no. 1.
    16	The world <Happy> is the same with "glad".
    17	I like dog.
    18	google is the best tools for search keyword.
    19	goooooogle yes!
    20	go! go! Let's go.
    21	# I am VBird

增加三行如下，每行末尾用\分隔

[[email protected] ~]$ nl regular_express.txt |sed '2a dalianmao\
> 23:root\
> 45:fidss\'
     1	"Open Source" is a good mechanism to develop programs.
     2	apple is my favorite food.
dalianmao\
23:root\
45:fidss
     3	Football game is not use feet only.
     4	this dress doesn't fit me.
     5	However, this dress is about $ 3183 dollars.
     6	GNU is free air not free beer.
     7	Her hair is very beauty.
     8	I can't finish the test.
     9	Oh! The soup taste good.
    10	motorcycle is cheap than car.
    11	This window is clear.
    12	the symbol '*' is represented as start.
    13	Oh!	My god!
    14	The gd software is a library for drafting programs.
    15	You are the best is mean you are the no. 1.
    16	The world <Happy> is the same with "glad".
    17	I like dog.
    18	google is the best tools for search keyword.
    19	goooooogle yes!
    20	go! go! Let's go.
    21	# I am VBird

注：如果增加在前面，把a换成i即可。

2) 以行为单位的取代与显示功能

sed [-nefr][动作]
选项与参数：
-n :使用安静(silent)模式。在一般sed的用法中，所有来自STDIN的数据一般都会被列出到屏幕上。但如果加上-n参数后，则只有经过sed特殊处理的那一行（或者动作）才会被列出来。

-e ：直接在指令列模式上进行sed的动作编辑；
-i ：直接修改读取的档案内容，而不是由屏幕输出。

动作说明：[n1[,n2]]function
n1,n2：不见得会存在，一般代表选择进行动作的行数，举例来说，如果我的动作是需要在10到20行之间进行的，则10，20[动作行为]

function有如下这些：

a：新增，a的后面可以接字符串，而这些字符串会在新的一行出现（目前的下一行）
c：取代，c的后面可以接字符串，这些字符串可以取代n1,n2之间的行
d：删除，因为是删除，所以d后面通常不接任何东西；
i：插入，i的后面可以接字符串，而这些字符串会在新的一行出现（目前的上一行);
s：取代，可以直接进行取代的工作，通常这个s的动作可以搭配正则表达式，例如'1,20s/old/new/g'就是了，如果new为变量的话，外面用双引号。

将第2-5 行的内容取代成为 'No 2-5 number'

[[email protected] ~]$ nl regular_express.txt |sed '2,5c No 2-5 number'
     1	"Open Source" is a good mechanism to develop programs.
No 2-5 number
     6	GNU is free air not free beer.
     7	Her hair is very beauty.
     8	I can't finish the test.
     9	Oh! The soup taste good.
    10	motorcycle is cheap than car.
    11	This window is clear.
    12	the symbol '*' is represented as start.
    13	Oh!	My god!
    14	The gd software is a library for drafting programs.
    15	You are the best is mean you are the no. 1.
    16	The world <Happy> is the same with "glad".
    17	I like dog.
    18	google is the best tools for search keyword.
    19	goooooogle yes!
    20	go! go! Let's go.
    21	# I am VBird

列出5-7行内容

[[email protected] ~]$ nl regular_express.txt |sed -n '5,7p'
     5	However, this dress is about $ 3183 dollars.
     6	GNU is free air not free beer.
     7	Her hair is very beauty.

3) 部分数据的搜寻并取代的功能

sed 's/要被取代的字符串/新的字符串/g'

获取ip地址

[[email protected] ~]$ /sbin/ifconfig eth0|grep 'inet addr'|sed 's/^.*addr://g'|sed 's/Bcast.*$//g'
192.168.235.129

只要MAN存在的那几行数据，但是含有#在内的批注我不要，而且空白行也不要

[[email protected] ~]$ cat /etc/man.config |grep 'MAN'|sed 's/#.*$//g'|sed '/^$/d'
MANPATH	/usr/man
MANPATH	/usr/share/man
MANPATH	/usr/local/man
MANPATH	/usr/local/share/man
MANPATH	/usr/X11R6/man
MANPATH_MAP	/bin			/usr/share/man
MANPATH_MAP	/sbin			/usr/share/man
MANPATH_MAP	/usr/bin		/usr/share/man
MANPATH_MAP	/usr/sbin		/usr/share/man
MANPATH_MAP	/usr/local/bin		/usr/local/share/man
MANPATH_MAP	/usr/local/sbin		/usr/local/share/man
MANPATH_MAP	/usr/X11R6/bin		/usr/X11R6/man
MANPATH_MAP	/usr/bin/X11		/usr/X11R6/man
MANPATH_MAP	/usr/bin/mh		/usr/share/man
MANSECT		1:1p:8:2:3:3p:4:5:6:7:9:0p:n:l:p:o:1x:2x:3x:4x:5x:6x:7x:8x

4)直接修改档案内容（危险操作！！！！）

将regular_express.txt 内每一行结尾若为.，则换成！

[[email protected] ~]$ sed -i 's/\.$/\!/g' regular_express.txt 
[[email protected] ~]$ cat regular_express.txt 
"Open Source" is a good mechanism to develop programs!
apple is my favorite food!
Football game is not use feet only!
this dress doesn't fit me!
However, this dress is about $ 3183 dollars.
GNU is free air not free beer.
Her hair is very beauty.
I can't finish the test.
Oh! The soup taste good.
motorcycle is cheap than car!
This window is clear!
the symbol '*' is represented as start!
Oh!	My god!
The gd software is a library for drafting programs.
You are the best is mean you are the no. 1!
The world <Happy> is the same with "glad"!
I like dog!
google is the best tools for search keyword!
goooooogle yes!
go! go! Let's go!
# I am VBird

利用sed直接在regular_express.txt 最后一行加入 #Hi，dalianmao

[[email protected] ~]$ sed -i '$a # Hi,dalianmao' regular_express.txt 
[[email protected] ~]$ cat regular_express.txt 
"Open Source" is a good mechanism to develop programs!
apple is my favorite food!
Football game is not use feet only!
this dress doesn't fit me!
However, this dress is about $ 3183 dollars.
GNU is free air not free beer.
Her hair is very beauty.
I can't finish the test.
Oh! The soup taste good.
motorcycle is cheap than car!
This window is clear!
the symbol '*' is represented as start!
Oh!	My god!
The gd software is a library for drafting programs.
You are the best is mean you are the no. 1!
The world <Happy> is the same with "glad"!
I like dog!
google is the best tools for search keyword!
goooooogle yes!
go! go! Let's go!
# I am VBird

# Hi,dalianmao

注：通过 wget http://linux.vbird.org/linux_basic/0330regularex/regular_express.txt 自行下载文档练习

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RE字符	意义与范例
^word	意义：待搜寻的字符串（word）在行首！范例：搜寻行首为#开始的那一行，并列出行号 grep -n '^#' regular_express.txt
word$	意义：带搜寻的字符串（word）在行尾！范例：将行尾为！的那一行打印出来，并列出行号 grep -n '!$' regular_express.txt
.	意义：代表一定有一个任意字符的字符！范例：搜寻的字符串可以是(eve) (eae) (eee) (e e),但不能仅有(ee) ! 亦即e与e中间一定仅有一个字符，而空格符也是字符！ grep -n 'e.e' reg
\	意义：跳脱字符，将特殊符号的特殊意义去除！范例：搜寻含有单引号'的那一行！ grep -n \' regular_express.txt
*	意义：重复零个到无穷多个的前一个RE字符范例：找出含有(es)(ess)(esss)等等的字符串，注意，因为可以是0个，所以es也是符合待搜寻字符串。另外，因为为重复前一个RE字符的符号，因此，在之前必须要紧接着一个RE字符喔！例如任意字符则为 .
[list]	意义：字符集合的RE字符，里面列出想要的字符！范例：搜寻含有(gl)或(gd)的那一行，需要特别留意的是，在[]当中仅代表一个待搜寻的字符，例如a[afl]y代表搜寻的字符串可以是aay,afy,aly即[afl]代表a或f或l的意思！ grep -n 'g[ld]' regular_express.txt
[n1-n2]	意义：字符集合的RE字符，里面列出想要获取的字符范围！范例：搜寻含有任意数字的那一行！需特别留意，在字符集合[]中的减号 - 是有特殊意义的，他代表两个字符之间的所有连续字符！但这个连续与否与ASCII编码有关，因此，你的编码需要设定正确（在bash当中，需要确定LANG与LANGUAGE的变量是否正确！）例如所有大写字符则为[A-Z] grep -n '[0-9]' regular_express.txt 或 grep -n '[[:digit:]]' regular_express.txt
[^list]	意义：字符集合的RE字符，里面列出不要的字符串或范围！范例：搜寻的字符串可以是(oog) (ood) 但不能是(oot),那个^在[]内时，代表的意义是反向选择的意思。例如，我不要大写字符，则为[^A-Z]。但是，需要特别注意的是，如果以grep -n [^A-Z] regular_express.txt 来搜寻，却发现该档案内的所有行都被列出，为什么？因为这个[^A-Z]是非大写字符的意思，因为每一行均有非大写字符，例如第一行的"Open Source" 就有p,e,n,o...等等的小写字 grep -n 'oo[^t]' regular_express.txt
\{n,m\}	意义：连续n到m个的前一个RE字符意义：若为\{n\}则是连续n个的前一个RE字符。意义：若是\{n,\}则是连续n个以上的前一个RE字符！范例：在g与g之间有2个到3个的o存在的字符串，亦即（goog）(gooog) grep -n 'go\{2,3\}g' regular_express.txt

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