基础正则表达式
语系对正则表达式的影响
不同语系下，字符的编码数据可能不同。
LANG=C：012……ABC……abc……
LANG=zh_CN：012……aAbB……
因此，使用[A-Z]时，搜索到的字符也不一样。
| 特殊符号 | 代表意义 |
| [:alnum:] | 大小写字符及数字，0-9，A-Z，a-z |
| [:alpha:] | 英文大小写字符 |
| [:blank:] | 空格键与tab键 |
| [:cntrl:] | 控制按键，CR，LF，TAB，DEL等 |
| [:digit:] | 代表数字 |
| [:graph:] | 除空格符（空格和Tab）外其他按键 |
| [:lower:] | 小写字符 |
| [:print:] | 可以被打印出来的字符 |
| [:punct:] | 标点字符，" ' ? ; : # $ |
| [:upper:] | 大写字符 |
| [:space:] | 任何会产生空白的字符 |
| [:xdigit:] | 十六进制数字 |
grep的一些高级参数
除了上一章介绍的基本用法，grep还有一些高级用法。
grep [-A] [-B] [--color=auto} '搜寻字符串‘ filename
参数：
-A：后面可加数字n，为after的意思，除了列出该列，后面的n列也列出来
-B：后面可加数字n，为after的意思，除了列出该列，前面的n列也列出来
--color=auto：对正确选取的数据着色
//-n用于显示行号 [root@localhost 桌面]# dmesg | grep -n --color=auto 'eth' 1730:[ 10.210383] e1000 0000:02:01.0 eth0: (PCI:66MHz:32-bit) 00:0c:29:7f:dd:91 1731:[ 10.210404] e1000 0000:02:01.0 eth0: Intel(R) PRO/1000 Network Connection
注：grep搜索到字符串后都是以整行为单位显示。
基础正则表达式练习
以下是练习文本
[root@localhost 桌面]# 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 [root@localhost 桌面]#
例题一：查找特定字符串
//查找含有the的行 [root@localhost 桌面]# grep -n 'the' regular_express.txt 8:I can't finish the test. 12:the symbol '*' is represented as start. 15:You are the best is mean you are the no. 1. 16:The world <Happy> is the same with "glad". 18:google is the best tools for search keyword. //查找不含有the的行 [root@localhost 桌面]# grep -vn 'the' regular_express.txt 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. 6:GNU is free air not free beer. 7:Her hair is very beauty. 9:Oh! The soup taste good. 10:motorcycle is cheap than car. 11:This window is clear. 13:Oh! My god! 14:The gd software is a library for drafting programs. 17:I like dog. 19:goooooogle yes! 20:go! go! Let's go. 21:# I am VBird 22: [root@localhost 桌面]#
例题二：利用中括号[]来查找集合字符
//查找tast或test字符串 [root@localhost 桌面]# grep -n 't[ae]st' regular_express.txt 8:I can't finish the test. 9:Oh! The soup taste good. //查找不是以g开头的oo字符串 [root@localhost 桌面]# grep -n '[^g]oo' regular_express.txt 2:apple is my favorite food. 3:Football game is not use feet only. 18:google is the best tools for search keyword. 19:goooooogle yes! //查找数字 [root@localhost 桌面]# grep -n '[0-9]' regular_express.txt 5:However, this dress is about $ 3183 dollars. 15:You are the best is mean you are the no. 1. 查找不是以小写字母开头的oo字符串 [root@localhost 桌面]# grep -n '[^[:lower:]]oo' regular_express.txt 3:Football game is not use feet only. [root@localhost 桌面]#
例题三：行首与行尾字符^$
//以the开头的行 [root@localhost 桌面]# grep -n '^the' regular_express.txt 12:the symbol '*' is represented as start. //以小写字母开头的行 [root@localhost 桌面]# grep -n '^[a-z]' regular_express.txt 2:apple is my favorite food. 4:this dress doesn't fit me. 10:motorcycle is cheap than car. 12:the symbol '*' is represented as start. 18:google is the best tools for search keyword. 19:goooooogle yes! 20:go! go! Let's go. //以小数点结尾的（需要转义） [root@localhost 桌面]# grep -n '.$' regular_express.txt 1:"Open Source" is a good mechanism to develop programs. 2:apple is my favorite food. 3:Football game is not use feet only. 4:this dress doesn't fit me. 10:motorcycle is cheap than car. 11:This window is clear. 12:the symbol '*' is represented as start. 15:You are the best is mean you are the no. 1. 16:The world <Happy> is the same with "glad". 17:I like dog. 18:google is the best tools for search keyword. 20:go! go! Let's go. //查找空白行 [root@localhost 桌面]# grep -n '^$' regular_express.txt 22: [root@localhost 桌面]#
例题四：任意字符.和重复字符*
.（小数点）：代表一定有一个任意字符的意思
*：代表重复前一个0到无穷的意思
//查找以g开头，d结尾，中间两个字符的字符 [root@localhost 桌面]# grep -n 'g..d' regular_express.txt 1:"Open Source" is a good mechanism to develop programs. 9:Oh! The soup taste good. 16:The world <Happy> is the same with "glad". //查找至少含有两个o，后面跟0到无穷个o的字符 [root@localhost 桌面]# grep -n 'ooo*' regular_express.txt 1:"Open Source" is a good mechanism to develop programs. 2:apple is my favorite food. 3:Football game is not use feet only. 9:Oh! The soup taste good. 18:google is the best tools for search keyword. 19:goooooogle yes! [root@localhost 桌面]#
例题五：限定连续RE字符范围{}
{}必须转义
//查找o重复两次的字符 [root@localhost 桌面]# grep -n 'o{2}' regular_express.txt 1:"Open Source" is a good mechanism to develop programs. 2:apple is my favorite food. 3:Football game is not use feet only. 9:Oh! The soup taste good. 18:google is the best tools for search keyword. 19:goooooogle yes! //查找o重复2到5次的字符 [root@localhost 桌面]# grep -n 'o{2,5}' regular_express.txt 1:"Open Source" is a good mechanism to develop programs. 2:apple is my favorite food. 3:Football game is not use feet only. 9:Oh! The soup taste good. 18:google is the best tools for search keyword. 19:goooooogle yes! //查找o重复两次以上的 [root@localhost 桌面]# grep -n 'go{2,}g' regular_express.txt 18:google is the best tools for search keyword. 19:goooooogle yes! [root@localhost 桌面]#
基础正则表达式字符
经过上节的五个例题，可将基础的正则表达式总结如下：
| RE字符 | 意义 | |
| ^word | 带查找的字符串在行首 | |
| word$ | 待查找的字符串在行尾 | |
| . | 代表一定有一个任意字符的字符 | |
| 转义字符 | ||
| * | 重复零到无穷多个前一个字符 | |
| [list] | 从字符集合的RE字符里找到想要选取的字符 | |
| [n1-n2] | 从字符集合的RE字符里找到想要选取的字符范围 | |
| [^list] |
|
|
| {n,m} | 前一个字符重复n到m次 |
sed工具
sed本身也是管道命令，不仅可以分析标准输出数据，还可以将数据进行替换、删除、新增和选取特定行等功能。
sed [-nefr] [动作]
参数：
-n：安静模式。默认情况下，所有来自STDIN的数据都会列在屏幕上，加上-n后，只有经过sed指令特殊处理的那一行才会显示出来
-e：直接在命令行模式上进行sed动作编辑
-f：直接将sed的动作写在一个文件内，-f filename则可以执行filename内的sed动作
-r：sed动作支持扩展性正则表达式（默认是基础型正则表达式）
-i：直接修改读取的文件内容，而不是屏幕输出
动作说明：[n1[,n2]] function
n1,n2不一定存在，一般代表选择动作的行数。
function有以下参数：
a：新增，a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：替换，c的后面可以接字符串，可以替换n1-n2行之间的行
d：删除
i：插入，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）
p：打印
s：替换，通常搭配正则表达式
//原始文本 [root@localhost 桌面]# cat -n test.txt 1 this a test text! 2 i like linux ! 3 today is monday! 4 my name is fw. 5 //删除2-3行 [root@localhost 桌面]# cat -n test.txt | sed '2,3d' 1 this a test text! 4 my name is fw. 5 //删除第3行及后面的 [root@localhost 桌面]# cat -n test.txt | sed '3,$d' 1 this a test text! 2 i like linux ! //新增（在后面） [root@localhost 桌面]# cat -n test.txt | sed '2a this line is new' 1 this a test text! 2 i like linux ! this line is new 3 today is monday! 4 my name is fw. 5 ////插入（在前面） [root@localhost 桌面]# cat -n test.txt | sed '2i this line is new' 1 this a test text! this line is new 2 i like linux ! 3 today is monday! 4 my name is fw. 5 //替换 [root@localhost 桌面]# cat -n test.txt | sed '2c this line is new' 1 this a test text! this line is new 3 today is monday! 4 my name is fw. 5 //显示2-4行 [root@localhost 桌面]# cat -n test.txt | sed -n '2,4p' 2 i like linux ! 3 today is monday! 4 my name is fw.
查找并替换：sed ‘s/要替换的字符串/新的字符串/g’
查找字符串可以使用正则表达式
//查看原文本 [root@localhost 桌面]# cat -n test.txt 1 this a test text! 2 i like linux ! 3 today is monday! 4 my name is fw. 5 //将this替换成that [root@localhost 桌面]# cat -n test.txt | sed 's/this/that/g' 1 that a test text! 2 i like linux ! 3 today is monday! 4 my name is fw. 5 //将结尾的！替换成小数点. [root@localhost 桌面]# cat -n test.txt | sed 's/!$/./g' 1 this a test text. 2 i like linux . 3 today is monday. 4 my name is fw. 5 //将开头的this删除 [root@localhost 桌面]# cat -n test.txt | sed 's/^.*this//g' a test text! 2 i like linux ! 3 today is monday! 4 my name is fw. 5 [root@localhost 桌面]#
直接修改文件内容：
-i参数
//查看原文件 [root@localhost 桌面]# cat test.txt this a test text! i like linux ! today is monday! my name is fw. //将this替换成that，写入原文件 [root@localhost 桌面]# sed -i 's/this/that/g' test.txt //查看原文件 [root@localhost 桌面]# cat test.txt that a test text! i like linux ! today is monday! my name is fw.
扩展正则表达式
该部分暂时略过。
文件的格式化与相关处理
格式化打印:printf
printf '打印格式' 实际内容
参数：
几个格式方面的特殊样式：
a：警告声音输出
：退格键
f：清除屏幕
：输出新的一行
：Enter按键
：水平Tab按键
v：垂直Tab按键
xNN：NN为两位数的数字，可以转换数字为字符
c程序语言内常见变量格式：
%ns：n是数字，s代表string，即多少个字符
%ni：n是数字，i代表integer，即多少个整数字数
%N.nf：n和N都是数字，f代表float
//查看原文本 [root@localhost 桌面]# cat test.txt Name Chinese English Math Average Tom 80 60 92 77.33 Sherry 75 55 80 70.00 John 60 90 70 73.33 [root@localhost 桌面]# printf '%s %s %s %s %s ' $(cat test.txt) Name Chinese English Math Average Tom 80 60 92 77.33 Sherry 75 55 80 70.00 John 60 90 70 73.33 [root@localhost 桌面]# printf '%10s %5i %5i %5i %8.3f ' $(cat test.txt) bash: printf: Chinese: 无效数字 bash: printf: English: 无效数字 bash: printf: Math: 无效数字 bash: printf: Average: 无效数字 Name 0 0 0 0.000 Tom 80 60 92 77.330 Sherry 75 55 80 70.000 John 60 90 70 73.330 //输出编码值为45的字符 [root@localhost 桌面]# printf 'x45 ' E [root@localhost 桌面]#
awk：好用的数据处理工具
awk ‘条件类型1{动作1} 条件类型2{动作2}……’ filename
[root@localhost 桌面]# last -n 5 root pts/0 :0 Mon Jul 18 14:19 still logged in root :0 :0 Mon Jul 18 14:10 still logged in (unknown :0 :0 Mon Jul 18 14:08 - 14:10 (00:01) reboot system boot 3.10.0-327.el7.x Mon Jul 18 14:08 - 16:00 (01:52) root pts/0 :0 Sun Jul 17 15:44 - crash (22:23) wtmp begins Mon Apr 25 13:36:45 2016 [root@localhost 桌面]# last -n 5 | awk '{print $1 " " $4}' root Mon root Mon (unknown Mon reboot 3.10.0-327.el7.x root Sun wtmp Apr [root@localhost 桌面]#
awk指令会把每一行根据空格或者tab分割，然后将所有片段依次赋值给$1,$2,……变量。
awk内置变量
NF：每行字段总数
NR：目前awk所处理的是第几行数据
FS：目前的分割字符，默认是空格
[root@localhost 桌面]# last -n 5 | awk '{print $1 " lines:" NR " cplumes:" NF}' root lines:1 cplumes:10 root lines:2 cplumes:10 (unknown lines:3 cplumes:10 reboot lines:4 cplumes:11 root lines:5 cplumes:10 lines:6 cplumes:0 wtmp lines:7 cplumes:7
awk的逻辑运算符
>：大于
<：小于
>=：大于等于
<=：小于等于
==：等于
!=：不等于
[root@localhost 桌面]# cat /etc/passwd root:x:0:0:root:/root:/bin/bash bin:x:1:1:bin:/bin:/sbin/nologin daemon:x:2:2:daemon:/sbin:/sbin/nologin adm:x:3:4:adm:/var/adm:/sbin/nologin lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin sync:x:5:0:sync:/sbin:/bin/sync shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown halt:x:7:0:halt:/sbin:/sbin/halt mail:x:8:12:mail:/var/spool/mail:/sbin/nologin operator:x:11:0:operator:/root:/sbin/nologin games:x:12:100:games:/usr/games:/sbin/nologin ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin //以下一“：”作为分隔符，但第一行会失效 [root@localhost 桌面]# cat /etc/passwd | > awk '{FS=":"} $3<10 {print $1 " " $3}' root:x:0:0:root:/root:/bin/bash bin 1 daemon 2 adm 3 lp 4 sync 5 shutdown 6 halt 7 mail 8 //以下利用BEGIN预先设置变量，第一行便不会失效 [root@localhost 桌面]# cat /etc/passwd | > awk 'BEGIN {FS=":"} $3<10 {print $1 " " $3}' root 0 bin 1 daemon 2 adm 3 lp 4 sync 5 shutdown 6 halt 7 mail 8 [root@localhost 桌面]#
awk的计算功能
//查看原文本 [root@localhost 桌面]# cat pay.txt Name 1st 2nd 3th Tom 2300 3200 1200 Sherry 3400 1200 7400 //在awk中变量可以直接使用，不需要$,awk的{}动作内若有多个命令辅助时，使用“；”分隔 [root@localhost 桌面]# cat pay.txt | > awk 'NR==1{printf "%10s %10s %10s %10s %10s ",$1,$2,$3,$4,"Total"} > NR>=2{total=$2+$3+$4;printf "%10s %10d %10d %10d %10.2f ",$1,$2,$3,$4,total}' Name 1st 2nd 3th Total Tom 2300 3200 1200 6700.00 Sherry 3400 1200 7400 12000.00
文件比较工具
diff
用于相似文件的比较。
diff [-bBi] fileA fileB
参数：
-b：忽略一行中多个空格的区别
-B：忽略空白行的区别
-i：忽略大小写区别
[root@localhost 桌面]# vim fileA [root@localhost 桌面]# cp fileA fileB [root@localhost 桌面]# vim fileB [root@localhost 桌面]# cat fileA this is fileA [root@localhost 桌面]# cat fileB this is fileB ok [root@localhost 桌面]# diff fileA fileB 1,2c1 < this is fileA < --- > this is fileB 3a3 > ok [root@localhost 桌面]#
patch
该命令与diff密不可分，加入fileA和fileB是两个不同版本的文件，想用fileB来更新fileA，则先通过diff比较两个文件的区别，并将区别文件制作成补丁文件，再由补丁文件更新旧文件。
patch -pN < patchFile 《==更新
patch -R -pN < patchFile 《==还原
参数：
-p：后面N表示取消几层目录
-R：代表还原
[root@localhost 桌面]# cat fileA this is fileA [root@localhost 桌面]# cat fileB this is fileB ok //制作补丁文件 [root@localhost 桌面]# diff -Naur fileA fileB > file.patch [root@localhost 桌面]# cat file.patch --- fileA 2016-07-18 16:36:24.371373349 +0800 +++ fileB 2016-07-18 16:37:31.523401652 +0800 @@ -1,3 +1,3 @@ -this is fileA - +this is fileB +ok //使用补丁文件更新旧文件，因为在当前目录，因此N为0 [root@localhost 桌面]# patch -p0 < file.patch patching file fileA [root@localhost 桌面]# cat fileA this is fileB ok [root@localhost 桌面]#