七.　grep家族:
?? ?
?? 1.? grep退出狀態(tài)：
?? ?0: 表示成功；
?? ?1: 表示在所提供的文件無法找到匹配的pattern；
?? ?2: 表示參數(shù)中提供的文件不存在。
?? ?見如下示例：
?? ?/> 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? #用戶root1并不存在
?? ?/> echo $?
?? ?1
?? ?
?? ?/> grep 'root' /etc/passwd1? #這里的/etc/passwd1文件并不存在
?? ?grep: /etc/passwd1: No such file or directory
?? ?/> echo $?
?? ?2
?? ?
?? 2.? grep中應(yīng)用正則表達(dá)式的實(shí)例：
?? ?需要說明的是下面所涉及的正則表達(dá)式在上一篇中已經(jīng)給出了詳細(xì)的說明，因此在看下面例子的時(shí)候，可以與前一篇的正則說明部分結(jié)合著看。
?? ?/> 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開頭的行。
?? ?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結(jié)尾的行。
?? ?northwest?????? NW????? Charles Main?? ??? ?3.0???? .98???? 3?????? 34
?? ?
?? ?/> grep '5\..' testfile #打印出第一個(gè)字符是5，后面跟著一個(gè).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開頭的行。
?? ?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開頭的行。
?? ?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 #打印出所有包含前兩個(gè)字符是大寫字符，后面緊跟一個(gè)空格及一個(gè)大寫字母的行。
?? ?eastern????????? EA????? TB Savage?????? 4.4???? .84???? 5?????? 20
?? ?northeast?????? NE????? AM Main Jr.????? 5.1???? .94???? 3?????? 13
?? ?注：在執(zhí)行以上命令時(shí)，如果不能得到預(yù)期的結(jié)果，即grep忽略了大小寫，導(dǎo)致這一問題的原因很可能是當(dāng)前環(huán)境的本地化的設(shè)置問題。對于以上命令，如果我將當(dāng)前語言設(shè)置為en_US的時(shí)候，它會打印出所有的行，當(dāng)我將其修改為中文環(huán)境時(shí)，就能得到我現(xiàn)在的輸出了。
?? ?/> export LANG=zh_CN? #設(shè)置當(dāng)前的語言環(huán)境為中文。
?? ?/> export LANG=en_US? #設(shè)置當(dāng)前的語言環(huán)境為美國。
?? ?/> export LANG=en_Br? #設(shè)置當(dāng)前的語言環(huán)境為英國。
?? ?
?? ?/> grep '[a-z]\{9\}' testfile #打印所有包含每個(gè)字符串至少有9個(gè)連續(xù)小寫字符的字符串的行。
?? ?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
?? ?
?? ?#第一個(gè)字符是3，緊跟著一個(gè)句點(diǎn)，然后是任意一個(gè)數(shù)字，然后是任意個(gè)任意字符，然后又是一個(gè)3，然后是制表符，然后又是一個(gè)3，需要說明的是，下面正則中的\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開頭的單詞的行。
?? ?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? #打印所有包含單詞north的行。
?? ?north?????????? NO????? Margot Weber?? ??? ?4.5???? .89???? 5?????? 9
?? ?
?? ?/> grep '^n\w*' testfile????? #第一個(gè)字符是n，后面是任意字母或者數(shù)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.? 擴(kuò)展grep(grep -E 或者 egrep)：
?? ?使用擴(kuò)展grep的主要好處是增加了額外的正則表達(dá)式元字符集。下面我們還是繼續(xù)使用實(shí)例來演示擴(kuò)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，將不會有結(jié)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???? #對于標(biāo)準(zhǔn)grep，如果在擴(kuò)展元字符前面加\，grep會自動啟用擴(kuò)展選項(xiàng)-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??????? #這3條命令將會打印出相同的結(jié)果，即所有包含一個(gè)或多個(gè)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，其后緊跟著0個(gè)或1個(gè)點(diǎn)，后面再是0和9之間的數(shù)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個(gè)命令返回相同結(jié)果，即打印一個(gè)或者多個(gè)連續(xù)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 #首先是一個(gè)或者多個(gè)字母，緊跟著一個(gè)或者多個(gè)非字母數(shù)字，最后一個(gè)是ABC中的一個(gè)。
?? ?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個(gè)命令返回相同結(jié)果，即以S或s開頭，緊跟著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開頭，其中es為\1的值，后面緊跟著任意數(shù)量的任意字符，最后還有一個(gè)es出現(xiàn)在該行。
?? ?northwest?????? NW????? Charles Main?? ??? ?3.0???? .98???? 3?????? 34
???

??? 4.? grep選項(xiàng)：
?? ?這里先列出grep常用的命令行選項(xiàng)：

選項(xiàng)	說明
-c	只顯示有多少行匹配，而不具體顯示匹配的行。
-h	不顯示文件名。
-i	在字符串比較的時(shí)候忽略大小寫。
-l	只顯示包含匹配模板的行的文件名清單。
-L	只顯示不包含匹配模板的行的文件名清單。
-n	在每一行前面打印改行在文件中的行數(shù)。
-v	反向檢索，只顯示不匹配的行。
-w	只顯示完整單詞的匹配。
-x	只顯示完整行的匹配。
-r/-R	如果文件參數(shù)是目錄，該選項(xiàng)將遞歸搜索該目錄下的所有子目錄和文件。

??? /> grep -n '^south' testfile? #-n選項(xiàng)在每一個(gè)匹配行的前面打印行號。
?? ?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選項(xiàng)關(guān)閉了大小寫敏感。
?? ?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只打印整個(gè)單詞匹配的行。
?? ?north?????????? NO????? Margot Weber??? 4.5???? .89???? 5?????? 9

??? /> grep -C 2 Patricia testfile #打印匹配行及其上下各兩行。
?? ?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 #打印匹配行及其前兩行。
?? ?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 #打印匹配行及其后兩行。
?? ?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

總結(jié)

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