diff --git a/sources/tech/Linux or UNIX grep Command Tutorial series/20151127 Linux or UNIX grep Command Tutorial series 2--Regular Expressions In grep.md b/sources/tech/Linux or UNIX grep Command Tutorial series/20151127 Linux or UNIX grep Command Tutorial series 2--Regular Expressions In grep.md deleted file mode 100644 index 8bac50fe25..0000000000 --- a/sources/tech/Linux or UNIX grep Command Tutorial series/20151127 Linux or UNIX grep Command Tutorial series 2--Regular Expressions In grep.md +++ /dev/null @@ -1,290 +0,0 @@ -(translating by runningwater) -Regular Expressions In grep -================================================================================ -How do I use the Grep command with regular expressions on a Linux and Unix-like operating systems? - -Linux comes with GNU grep, which supports extended regular expressions. GNU grep is the default on all Linux systems. The grep command is used to locate information stored anywhere on your server or workstation. - -### Regular Expressions ### - -Regular Expressions is nothing but a pattern to match for each input line. A pattern is a sequence of characters. Following all are examples of pattern: - - ^w1 - w1|w2 - [^ ] - -#### grep Regular Expressions Examples #### - -Search for 'vivek' in /etc/passswd - - grep vivek /etc/passwd - -Sample outputs: - - vivek:x:1000:1000:Vivek Gite,,,:/home/vivek:/bin/bash - vivekgite:x:1001:1001::/home/vivekgite:/bin/sh - gitevivek:x:1002:1002::/home/gitevivek:/bin/sh - -Search vivek in any case (i.e. case insensitive search) - - grep -i -w vivek /etc/passwd - -Search vivek or raj in any case - - grep -E -i -w 'vivek|raj' /etc/passwd - -The PATTERN in last example, used as an extended regular expression. - -### Anchors ### - -You can use ^ and $ to force a regex to match only at the start or end of a line, respectively. The following example displays lines starting with the vivek only: - - grep ^vivek /etc/passwd - -Sample outputs: - - vivek:x:1000:1000:Vivek Gite,,,:/home/vivek:/bin/bash - vivekgite:x:1001:1001::/home/vivekgite:/bin/sh - -You can display only lines starting with the word vivek only i.e. do not display vivekgite, vivekg etc: - - grep -w ^vivek /etc/passwd - -Find lines ending with word foo: -grep 'foo$' filename - -Match line only containing foo: - - grep '^foo$' filename - -You can search for blank lines with the following examples: - - grep '^$' filename - -### Character Class ### - -Match Vivek or vivek: - - grep '[vV]ivek' filename - -OR - - grep '[vV][iI][Vv][Ee][kK]' filename - -You can also match digits (i.e match vivek1 or Vivek2 etc): - - grep -w '[vV]ivek[0-9]' filename - -You can match two numeric digits (i.e. match foo11, foo12 etc): - - grep 'foo[0-9][0-9]' filename - -You are not limited to digits, you can match at least one letter: - - grep '[A-Za-z]' filename - -Display all the lines containing either a "w" or "n" character: - - grep [wn] filename - -Within a bracket expression, the name of a character class enclosed in "[:" and ":]" stands for the list of all characters belonging to that class. Standard character class names are: - -- [:alnum:] - Alphanumeric characters. -- [:alpha:] - Alphabetic characters -- [:blank:] - Blank characters: space and tab. -- [:digit:] - Digits: '0 1 2 3 4 5 6 7 8 9'. -- [:lower:] - Lower-case letters: 'a b c d e f g h i j k l m n o p q r s t u v w x y z'. -- [:space:] - Space characters: tab, newline, vertical tab, form feed, carriage return, and space. -- [:upper:] - Upper-case letters: 'A B C D E F G H I J K L M N O P Q R S T U V W X Y Z'. - -In this example match all upper case letters: - - grep '[:upper:]' filename - -### Wildcards ### - -You can use the "." for a single character match. In this example match all 3 character word starting with "b" and ending in "t": - - grep '\' filename - -Where, - -- \< Match the empty string at the beginning of word -- \> Match the empty string at the end of word. - -Print all lines with exactly two characters: - - grep '^..$' filename - -Display any lines starting with a dot and digit: - - grep '^\.[0-9]' filename - -#### Escaping the dot #### - -The following regex to find an IP address 192.168.1.254 will not work: - - grep '192.168.1.254' /etc/hosts - -All three dots need to be escaped: - - grep '192\.168\.1\.254' /etc/hosts - -The following example will only match an IP address: - - egrep '[[:digit:]]{1,3}\.[[:digit:]]{1,3}\.[[:digit:]]{1,3}\.[[:digit:]]{1,3}' filename - -The following will match word Linux or UNIX in any case: - - egrep -i '^(linux|unix)' filename - -### How Do I Search a Pattern Which Has a Leading - Symbol? ### - -Searches for all lines matching '--test--' using -e option Without -e, grep would attempt to parse '--test--' as a list of options: - - grep -e '--test--' filename - -### How Do I do OR with grep? ### - -Use the following syntax: - - grep 'word1|word2' filename - -OR - - grep 'word1\|word2' filename - -### How Do I do AND with grep? ### - -Use the following syntax to display all lines that contain both 'word1' and 'word2' - - grep 'word1' filename | grep 'word2' - -### How Do I Test Sequence? ### - -You can test how often a character must be repeated in sequence using the following syntax: - - {N} - {N,} - {min,max} - -Match a character "v" two times: - - egrep "v{2}" filename - -The following will match both "col" and "cool": - - egrep 'co{1,2}l' filename - -The following will match any row of at least three letters 'c'. - - egrep 'c{3,}' filename - -The following example will match mobile number which is in the following format 91-1234567890 (i.e twodigit-tendigit) - - grep "[[:digit:]]\{2\}[ -]\?[[:digit:]]\{10\}" filename - -### How Do I Hightlight with grep? ### - -Use the following syntax: - - grep --color regex filename - -How Do I Show Only The Matches, Not The Lines? - -Use the following syntax: - - grep -o regex filename - -### Regular Expression Operator ### - -注：表格 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Regex operatorMeaning
.Matches any single character.
?The preceding item is optional and will be matched, at most, once.
*The preceding item will be matched zero or more times.
+The preceding item will be matched one or more times.
{N}The preceding item is matched exactly N times.
{N,}The preceding item is matched N or more times.
{N,M}The preceding item is matched at least N times, but not more than M times.
-Represents the range if it's not first or last in a list or the ending point of a range in a list.
^Matches the empty string at the beginning of a line; also represents the characters not in the range of a list.
$Matches the empty string at the end of a line.
\bMatches the empty string at the edge of a word.
\BMatches the empty string provided it's not at the edge of a word.
\<Match the empty string at the beginning of word.
\> Match the empty string at the end of word.
- -#### grep vs egrep #### - -egrep is the same as **grep -E**. It interpret PATTERN as an extended regular expression. From the grep man page: - - In basic regular expressions the meta-characters ?, +, {, |, (, and ) lose their special meaning; instead use the backslashed versions \?, \+, \{, - \|, \(, and \). - Traditional egrep did not support the { meta-character, and some egrep implementations support \{ instead, so portable scripts should avoid { in - grep -E patterns and should use [{] to match a literal {. - GNU grep -E attempts to support traditional usage by assuming that { is not special if it would be the start of an invalid interval specification. - For example, the command grep -E '{1' searches for the two-character string {1 instead of reporting a syntax error in the regular expression. - POSIX.2 allows this behavior as an extension, but portable scripts should avoid it. - -References: - -- man page grep and regex(7) -- info page grep` - --------------------------------------------------------------------------------- - -via: http://www.cyberciti.biz/faq/grep-regular-expressions/ - -作者：Vivek Gite -译者：[runningwater](https://github.com/runningwater) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 \ No newline at end of file diff --git a/translated/tech/Linux or UNIX grep Command Tutorial series/20151127 Linux or UNIX grep Command Tutorial series 2--Regular Expressions In grep.md b/translated/tech/Linux or UNIX grep Command Tutorial series/20151127 Linux or UNIX grep Command Tutorial series 2--Regular Expressions In grep.md new file mode 100755 index 0000000000..8389f4c339 --- /dev/null +++ b/translated/tech/Linux or UNIX grep Command Tutorial series/20151127 Linux or UNIX grep Command Tutorial series 2--Regular Expressions In grep.md @@ -0,0 +1,288 @@ +## grep 中的正则表达式 +================================================================================ +在 Linux 、类 Unix 系统中我该如何使用 Grep 命令的正则表达式呢？ + +Linux 附带有 GNU grep 命令工具，它支持正则表达式，而且 GNU grep 在所有的 Linux 系统中都是默认有的。Grep 命令被用于搜索定位存储在您服务器或工作站的信息。 + +### 正则表达式 ### + +正则表达式仅仅是对每个输入行的匹配的一种模式，即对字符序列的匹配模式。下面是范例： + + ^w1 + w1|w2 + [^ ] + +#### grep 正则表达式示例 #### + +在 /etc/passswd 目录中搜索 'vivek' + + grep vivek /etc/passwd + +输出例子: + + vivek:x:1000:1000:Vivek Gite,,,:/home/vivek:/bin/bash + vivekgite:x:1001:1001::/home/vivekgite:/bin/sh + gitevivek:x:1002:1002::/home/gitevivek:/bin/sh + +摸索任何情况下的 vivek(即不区分大小写的搜索) + + grep -i -w vivek /etc/passwd + +摸索任何情况下的 vivek 或 raj + + grep -E -i -w 'vivek|raj' /etc/passwd + +上面最后的例子显示的，就是一个正则表达式扩展的模式。 + +### 锚 ### + +你可以分别使用 ^ 和 $ 符号来正则匹配输入行的开始或结尾。下面的例子搜索显示仅仅以 vivek 开始的输入行： + + grep ^vivek /etc/passwd + +输出例子: + + vivek:x:1000:1000:Vivek Gite,,,:/home/vivek:/bin/bash + vivekgite:x:1001:1001::/home/vivekgite:/bin/sh + +你可以仅仅只搜索出以单词 vivek 开始的行，即不显示 vivekgit、vivekg 等 + + grep -w ^vivek /etc/passwd + +找出以单词 word 结尾的行： + + grep 'foo$' 文件名 + +匹配仅仅只包含 foo 的行： + + grep '^foo$' 文件名 + +如下所示的例子可以搜索空行： + + grep '^$' 文件名 + +### 字符类 ### + +匹配 Vivek 或 vivek： + + grep '[vV]ivek' 文件名 + +或者 + + grep '[vV][iI][Vv][Ee][kK]' 文件名 + +也可以匹配数字 (即匹配 vivek1 或 Vivek2 等等): + + grep -w '[vV]ivek[0-9]' 文件名 + +可以匹配两个数字字符(即 foo11、foo12 等): + + grep 'foo[0-9][0-9]' 文件名 + +不仅仅局限于数字，也能匹配至少一个字母的: + + grep '[A-Za-z]' 文件名 + +显示含有"w" 或 "n" 字符的所有行： + + grep [wn] 文件名 + +在括号内的表达式，即包在"[:" 和 ":]" 之间的字符类的名字，它表示的是属于此类的所有字符列表。标准的字符类名称如下： + +- [:alnum:] - 字母数字字符. +- [:alpha:] - 字母字符 +- [:blank:] - 空字符: 空格键符 和 制表符. +- [:digit:] - 数字: '0 1 2 3 4 5 6 7 8 9'. +- [:lower:] - 小写字母: 'a b c d e f g h i j k l m n o p q r s t u v w x y z'. +- [:space:] - 空格字符: 制表符、换行符、垂直制表符、换页符、回车符和空格键符. +- [:upper:] - 大写字母: 'A B C D E F G H I J K L M N O P Q R S T U V W X Y Z'. + +例子所示的是匹配所有大写字母: + + grep '[:upper:]' 文件名 + +### 通配符 ### + +你可以使用 "." 来匹配单个字符。例子中匹配以"b"开头以"t"结尾的3个字符的单词： + + grep '\' 文件名 + +在这儿, + +- \< 匹配单词前面的空字符串 +- \> 匹配单词后面的空字符串 + +打印出只有两个字符的所有行: + + grep '^..$' 文件名 + +显示以一个点和一个数字开头的行： + + grep '^\.[0-9]' 文件名 + +#### 点号转义 #### + +下面要匹配到 IP 地址为 192.168.1.254 的正则式是不会工作的: + + egrep '192.168.1.254' /etc/hosts + +三个点符号都需要转义： + + grep '192\.168\.1\.254' /etc/hosts + +下面的例子仅仅匹配出 IP 地址： + + egrep '[[:digit:]]{1,3}\.[[:digit:]]{1,3}\.[[:digit:]]{1,3}\.[[:digit:]]{1,3}' 文件名 + +下面的例子会匹配任意大小写的 Linux 或 UNIX 这两个单词： + + egrep -i '^(linux|unix)' 文件名 + +### 怎么样搜索以 - 符号开头的匹配模式？ ### + +要使用 -e 选项来搜索匹配 '--test--' 字符串，如果不使用 -e 选项，grep 命令会试图把 '--test--' 当作自己的选项参数来解析： + + grep -e '--test--' 文件名 + +### 怎么使用 grep 的 OR 匹配? ### + +使用如下的语法： + + grep 'word1|word2' 文件名 + +或者是 + + grep 'word1\|word2' 文件名 + +### 怎么使用 grep 的 AND 匹配? ### + +使用下面的语法来显示既包含 'word1' 又包含 'word2' 的所有行 + + grep 'word1' 文件名 | grep 'word2' + +### 怎么样使用序列检测? ### + +使用如下的语法，您可以检测一个字符在序列中重复出现次数： + + {N} + {N,} + {min,max} + +要匹配字符 “v" 出现两次： + + egrep "v{2}" 文件名 + +下面的命令能匹配到 "col" 和 "cool" ： + + egrep 'co{1,2}l' 文件名 + +下面的命令将会匹配出至少有三个 'c' 字符的所有行。 + + egrep 'c{3,}' 文件名 + +下面的例子会匹配 91-1234567890（即二个数字-十个数字） 这种格式的手机号。 + + grep "[[:digit:]]\{2\}[ -]\?[[:digit:]]\{10\}" 文件名 + +### 怎么样使 grep 命令突出显示？### + +使用如下的语法： + + grep --color regex 文件名 + +### 怎么样仅仅只显示匹配出的字符，而不是匹配出的行？ ### + +使用如下语法： + + grep -o regex 文件名 + +### 正则表达式限定符### + +注：表格 + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
限定符描述
.匹配任意的一个字符.
?匹配前面的子表达式,最多一次。
*匹配前面的子表达式零次或多次。
+匹配前面的子表达式一次或多次。
{N}匹配前面的子表达式 N 次。
{N,}匹配前面的子表达式 N 次到多次。
{N,M}匹配前面的子表达式 N 到 M 次，至少 N 次至多 M 次。
-只要不是在序列开始、结尾或者序列的结束点上，表示序列范围
^匹配一行开始的空字符串；也表示字符不在要匹配的列表中。
$匹配一行末尾的空字符串。
\b匹配一个单词前后的空字符串。
\B匹配一个单词中间的空字符串
\<匹配单词前面的空字符串。
\> 匹配单词后面的空字符串。
+ +#### grep 和 egrep #### + +egrep 跟 **grep -E** 是一样的。他会以正则表达式的模式来解释。下面是 grep 的帮助页(man): + + 基本的正则表达式元字符 ?、+、 {、 |、 ( 和 ) 已经失去了他们特殊的意义，要使用的话用反斜线的版本 \?、\+、\{、\|、\( 和 \) 来代替。 + 传统的 egrep 不支持 { 元字符，一些 egrep 的实现是以 \{ 替代的，所以有 grep -E 的通用脚本应该避免使用 { 符号，要匹配字面的 { 应该使用 [}]。 + GNU grep -E 试图支持传统的用法，如果 { 出在在无效的间隔规范字符串这前，它就会假定 { 不是特殊字符。 + 例如，grep -E '{1' 命令搜索包含 {1 两个字符的串，而不会报出正则表达式语法错误。 + POSIX.2 标准允许对这种操作的扩展，但在可移植脚本文件里应该避免这样使用。 + +引用: + +- grep 和 regex 帮助手册页(7) +- grep 的 info 页` + +-------------------------------------------------------------------------------- + +via: http://www.cyberciti.biz/faq/grep-regular-expressions/ + +作者：Vivek Gite +译者：[runningwater](https://github.com/runningwater) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 \ No newline at end of file