Linux Shell常用技巧(二)
转自：http://www.cnblogs.com/stephen-liu74/archive/2011/11/14/2243694.html
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七. grep家族:
?? ?
???1.? grep退出状态：
?? ?0: 表示成功；
?? ?1: 表示在所提供的文件无法找到匹配的pattern；
?? ?2: 表示参数中提供的文件不存在。
?? ?见如下示例：
?? ?/> grep 'root' /etc/passwd
?? ?root:x:0:0:root:/root:/bin/bash
?? ?operator:x:11:0:operator:/root:/sbin/nologin
?? ?/> echo $?
?? ?0
?? ?
?? ?/> grep 'root1' /etc/passwd? #用户root1并不存在
?? ?/> echo $?
?? ?1
?? ?
?? ?/> grep 'root' /etc/passwd1? #这里的/etc/passwd1文件并不存在
?? ?grep: /etc/passwd1: No such file or directory
?? ?/> echo $?
?? ?2
?? ?
???2.? grep中应用正则表达式的实例：
?? ?需要说明的是下面所涉及的正则表达式在上一篇中已经给出了详细的说明，因此在看下面例子的时候，可以与前一篇的正则说明部分结合着看。
?? ?/> cat testfile
??? northwest??????? NW????? Charles Main?????????? 3.0???? .98???? 3?????? 34
?? ?western?????????? WE?????? Sharon Gray????????? 5.3???? .97???? 5?????? 23
?? ?southwest?????? SW?????? Lewis Dalsass???????? 2.7???? .8?????? 2?????? 18
?? ?southern???????? SO?????? Suan Chin?????????????? 5.1???? .95???? 4?????? 15
?? ?southeast?????? SE??????? Patricia Hemenway??? 4.0???? .7?????? 4?????? 17
?? ?eastern?????????? EA??????? TB Savage??????????? ? 4.4???? .84???? 5?????? 20
?? ?northeast??????? NE??????? AM Main Jr.????????????? 5.1???? .94???? 3?????? 13
?? ?north????????????? NO?????? Margot Weber????????? 4.5???? .89???? 5?????? 9
?? ?central??????? ? ? CT??????? Ann Stephens????????? 5.7???? .94???? 5?????? 13
????
?? ?/> grep NW testfile???? #打印出testfile中所有包含NW的行。
?? ?northwest?????? NW????? Charles Main?? ??? ?3.0???? .98???? 3?????? 34
?? ?
?? ?/> grep '^n' testfile?? #打印出以n开头的行。
?? ?northwest?????? NW????? Charles Main?? ??? ?3.0???? .98???? 3?????? 34
?? ?northeast??????? NE?????? AM Main Jr.??? ??? ? 5.1???? .94???? 3?????? 13
?? ?north????????????? NO????? Margot Weber?? ?? 4.5???? .89???? 5?????? 9
?? ?
?? ?/> grep '4$' testfile?? #打印出以4结尾的行。
?? ?northwest?????? NW????? Charles Main?? ??? ?3.0???? .98???? 3?????? 34
?? ?
?? ?/> grep '5\..' testfile?#打印出第一个字符是5，后面跟着一个.字符，在后面是任意字符的行。
?? ?western???????? WE????? Sharon Gray??? ??? ?5.3???? .97???? 5?????? 23
?? ?southern??????? SO????? Suan Chin????? ??? ?? 5.1???? .95???? 4?????? 15
?? ?northeast?????? NE????? AM Main Jr.??? ??? ??? 5.1???? .94???? 3?????? 13
?? ?central?????????? CT????? Ann Stephens?? ??? ?5.7???? .94???? 5?????? 13
?? ?
?? ?/> grep '\.5' testfile? #打印出所有包含.5的行。
?? ?north?????????? NO????? Margot Weber?? ??? ?4.5???? .89???? 5?????? 9
?? ?/> grep '^[we]' testfile?#打印出所有以w或e开头的行。
?? ?western???????? WE????? Sharon Gray??? ??? ?5.3???? .97???? 5?????? 23
?? ?eastern????????? EA????? TB Savage????? ??? ? 4.4???? .84???? 5?????? 20
?? ?
?? ?/> grep '[^0-9]' testfile?#打印出所有不是以0-9开头的行。
?? ?northwest?????? NW???? Charles Main?? ??? ????? 3.0???? .98????? 3?????? 34
?? ?western????????? WE????? Sharon Gray??? ??? ???? 5.3???? .97???? 5?????? 23
?? ?southwest?????? SW???? Lewis Dalsass? ??? ???? 2.7???? .8?????? 2?????? 18
?? ?southern???????? SO????? Suan Chin????? ??? ????? 5.1???? .95???? 4?????? 15
?? ?southeast??????? SE????? Patricia Hemenway?? ? 4.0???? .7????? 4?????? 17
?? ?eastern?????????? EA????? TB Savage????? ??? ????? 4.4???? .84???? 5?????? 20
?? ?northeast??????? NE????? AM Main Jr.??? ??? ??????? 5.1???? .94???? 3?????? 13
?? ?north????????????? NO????? Margot Weber?? ??? ??? 4.5???? .89???? 5?????? 9
?? ?central??????????? CT????? Ann Stephens?? ??? ???? 5.7???? .94???? 5?????? 13
?? ?/> grep '[A-Z][A-Z] [A-Z]' testfile?#打印出所有包含前两个字符是大写字符，后面紧跟一个空格及一个大写字母的行。
?? ?eastern????????? EA????? TB Savage?????? 4.4???? .84???? 5?????? 20
?? ?northeast?????? NE????? AM Main Jr.????? 5.1???? .94???? 3?????? 13
?? ?注：在执行以上命令时，如果不能得到预期的结果，即grep忽略了大小写，导致这一问题的原因很可能是当前环境的本地化的设置问题。对于以上命令，如果我将当前语言设置为en_US的时候，它会打印出所有的行，当我将其修改为中文环境时，就能得到我现在的输出了。
?? ?/> export LANG=zh_CN? #设置当前的语言环境为中文。
?? ?/> export LANG=en_US? #设置当前的语言环境为美国。
????/> export LANG=en_Br? #设置当前的语言环境为英国。
?? ?
?? ?/> grep '[a-z]\{9\}' testfile?#打印所有包含每个字符串至少有9个连续小写字符的字符串的行。
?? ?northwest??????? NW????? Charles Main?? ??? ?? 3.0???? .98???? 3?????? 34
?? ?southwest?????? SW????? Lewis Dalsass? ??? ?? 2.7???? .8?????? 2?????? 18
?? ?southeast??????? SE????? Patricia Hemenway?? 4.0???? .7?????? 4?????? 17
?? ?northeast??????? NE????? AM Main Jr.??? ??? ????? 5.1???? .94???? 3?????? 13
?? ?
?? ?#第一个字符是3，紧跟着一个句点，然后是任意一个数字，然后是任意个任意字符，然后又是一个3，然后是制表符，然后又是一个3，需要说明的是，下面正则中的\1表示\(3\)。
?? ?/> grep '\(3\)\.[0-9].*\1??? *\1' testfile?
?? ?northwest?????? NW????? Charles Main?? ??? ?3.0???? .98???? 3?????? 34
?? ?
????/> grep '\<north' testfile????#打印所有以north开头的单词的行。
?? ?northwest?????? NW????? Charles Main?? ??? ?? 3.0???? .98???? 3?????? 34
?? ?northeast??????? NE?????? AM Main Jr.??? ??? ??? 5.1???? .94???? 3?????? 13
?? ?north????????????? NO????? Margot Weber?? ??? ?4.5???? .89???? 5?????? 9
?? ?
?? ?/> grep '\<north\>' testfile??#打印所有包含单词north的行。
?? ?north?????????? NO????? Margot Weber?? ??? ?4.5???? .89???? 5?????? 9
?? ?
?? ?/> grep '^n\w*' testfile????? #第一个字符是n，后面是任意字母或者数字。
?? ?northwest?????? NW???? Charles Main?? ??? ?? 3.0???? .98???? 3?????? 34
?? ?northeast??????? NE????? AM Main Jr.??? ??? ??? 5.1???? .94???? 3?????? 13
?? ?north???????????? NO????? Margot Weber?? ??? ?4.5???? .89???? 5?????? 9
?? ?
?? ?3.? 扩展grep(grep -E 或者 egrep)：
?? ?使用扩展grep的主要好处是增加了额外的正则表达式元字符集。下面我们还是继续使用实例来演示扩展grep。
?? ?/> egrep 'NW|EA' testfile???? #打印所有包含NW或EA的行。如果不是使用egrep，而是grep，将不会有结果查出。
?? ?northwest?????? NW????? Charles Main?? ??? ?3.0???? .98???? 3?????? 34
?? ?eastern???????? EA????? TB Savage????? ??? ?4.4???? .84???? 5?????? 20
?? ?
?? ?/> grep 'NW\|EA' testfile???? #对于标准grep，如果在扩展元字符前面加\，grep会自动启用扩展选项-E。
?? ?northwest?????? NW????? Charles Main?? ??? ?3.0???? .98???? 3?????? 34
?? ?eastern?????????? EA?????? TB Savage????? ??? ?4.4???? .84???? 5?????? 20
?? ?
????/> egrep '3+' testfile
?? ?/> grep -E '3+' testfile
?? ?/> grep '3\+' testfile??????? #这3条命令将会打印出相同的结果，即所有包含一个或多个3的行。
?? ?northwest?????? NW????? Charles Main?? ??? ? 3.0???? .98???? 3?????? 34
?? ?western????????? WE????? Sharon Gray??? ??? ?5.3???? .97???? 5?????? 23
?? ?northeast??????? NE?????? AM Main Jr.??? ??? ?? 5.1???? .94???? 3?????? 13
?? ?central??????????? CT?????? Ann Stephens?? ??? 5.7???? .94???? 5?????? 13
?? ?
?? ?/> egrep '2\.?[0-9]' testfile?
?? ?/> grep -E '2\.?[0-9]' testfile
?? ?/> grep '2\.\?[0-9]' testfile?#首先含有2字符，其后紧跟着0个或1个点，后面再是0和9之间的数字。
?? ?western???????? WE?????? Sharon Gray??? ??? ? 5.3???? .97???? 5?????? 23
?? ?southwest????? SW????? Lewis Dalsass? ??? ?? 2.7???? .8????? 2?????? 18
?? ?eastern????????? EA?????? TB Savage????? ??? ?? 4.4???? .84???? 5?????? 20
?? ?
?? ?/> egrep '(no)+' testfile
?? ?/> grep -E '(no)+' testfile
?? ?/> grep '\(no\)\+' testfile?? #3个命令返回相同结果，即打印一个或者多个连续的no的行。
?? ?northwest?????? NW????? Charles Main?? ??? ?3.0???? .98???? 3?????? 34
?? ?northeast??????? NE?????? AM Main Jr.??? ??? ? 5.1???? .94???? 3?????? 13
?? ?north????????????? NO????? Margot Weber?? ?? 4.5???? .89???? 5?????? 9
?? ?
?? ?/> grep -E '\w+\W+[ABC]' testfile?#首先是一个或者多个字母，紧跟着一个或者多个非字母数字，最后一个是ABC中的一个。
?? ?northwest?????? NW???? Charles Main?? ??? 3.0???? .98???? 3?????? 34
?? ?southern??????? SO????? Suan Chin????? ??? ?5.1???? .95???? 4?????? 15
?? ?northeast?????? NE????? AM Main Jr.??? ??? ? 5.1???? .94???? 3?????? 13
?? ?central?????????? CT????? Ann Stephens?? ?? 5.7???? .94???? 5?????? 13
?? ?
?? ?/> egrep '[Ss](h|u)' testfile
?? ?/> grep -E '[Ss](h|u)' testfile
?? ?/> grep '[Ss]\(h\|u\)' testfile?? #3个命令返回相同结果，即以S或s开头，紧跟着h或者u的行。
?? ?western???????? WE????? Sharon Gray??? ?? 5.3???? .97???? 5?????? 23
?? ?southern??????? SO????? Suan Chin????? ??? 5.1???? .95???? 4?????? 15
?? ?
?? ?/> egrep 'w(es)t.*\1' testfile??? #west开头，其中es为\1的值，后面紧跟着任意数量的任意字符，最后还有一个es出现在该行。
?? ?northwest?????? NW????? Charles Main?? ??? ?3.0???? .98???? 3?????? 34
???
??? 4.? grep选项：
?? ?这里先列出grep常用的命令行选项：
??? /> grep -n '^south' testfile? #-n选项在每一个匹配行的前面打印行号。
?? ?3:southwest???? SW????? Lewis Dalsass? ??? ?? 2.7???? .8????? 2?????? 18
?? ?4:southern?????? SO????? Suan Chin????? ??? ???? 5.1???? .95???? 4?????? 15
?? ?5:southeast????? SE????? Patricia Hemenway??? 4.0???? .7????? 4?????? 17
????/> grep -i 'pat' testfile???? #-i选项关闭了大小写敏感。
?? ?southeast?????? SE????? Patricia Hemenway?????? 4.0???? .7????? 4?????? 17
????/> grep -v 'Suan Chin' testfile?#打印所有不包含Suan Chin的行。
?? ?northwest?????? NW????? Charles Main?? ??? ?? 3.0???? .98???? 3?????? 34
?? ?western????????? WE????? Sharon Gray??? ??? ?? 5.3???? .97??? 5? ???? 23
?? ?southwest?????? SW????? Lewis Dalsass? ??? ? 2.7???? .8????? 2?????? 18
?? ?southeast??????? SE????? Patricia Hemenway?? 4.0???? .7????? 4?????? 17
?? ?eastern?????????? EA????? TB Savage????? ??? ??? 4.4???? .84???? 5? ???? 20
?? ?northeast??????? NE????? AM Main Jr.??? ??? ???? 5.1???? .94???? 3?????? 13
?? ?north????????????? NO????? Margot Weber?? ??? ?4.5???? .89???? 5?????? 9
?? ?central??????????? CT????? Ann Stephens?? ??? ? 5.7???? .94???? 5?????? 13
????/> grep -l 'ss' testfile??#-l使得grep只打印匹配的文件名，而不打印匹配的行。
?? ?testfile
????/> grep -c 'west' testfile?#-c使得grep只打印有多少匹配模板的行。
?? ?3
????/> grep -w 'north' testfile?#-w只打印整个单词匹配的行。
?? ?north?????????? NO????? Margot Weber??? 4.5???? .89???? 5?????? 9
????/> grep -C 2 Patricia testfile?#打印匹配行及其上下各两行。
?? ?southwest????? SW???? Lewis Dalsass? ??? ?? 2.7???? .8?????? 2?????? 18
?? ?southern??????? SO????? Suan Chin????? ??? ??? 5.1???? .95???? 4?????? 15
?? ?southeast?????? SE????? Patricia Hemenway?? 4.0???? .7????? 4?????? 17
?? ?eastern????????? EA????? TB Savage????? ??? ??? 4.4???? .84???? 5?????? 20
?? ?northeast?????? NE????? AM Main Jr.??? ??? ???? 5.1???? .94???? 3?????? 13
????/> grep -B 2 Patricia testfile?#打印匹配行及其前两行。
?? ?southwest????? SW????? Lewis Dalsass? ??? ?? 2.7???? .8????? 2?????? 18
?? ?southern??????? SO????? Suan Chin????? ??? ???? 5.1???? .95??? 4?????? 15
?? ?southeast?????? SE????? Patricia Hemenway?? 4.0???? .7????? 4?????? 17
????/> grep -A 2 Patricia testfile?#打印匹配行及其后两行。
?? ?southeast?????? SE????? Patricia Hemenway?? 4.0???? .7????? 4?????? 17
?? ?eastern?????????? EA????? TB Savage????? ??? ??? 4.4???? .84???? 5?????? 20
?? ?northeast?????? NE?????? AM Main Jr.??? ??? ???? 5.1???? .94???? 3?????? 13