【Shell命令】linux grep 查找匹配命令详解
【Shell命令】linux grep 查找匹配命令详解本文主要内容来自Linux man 手册
命令名称：
grep（global search regular express and print out line）打印匹配的行（内容）
类似的命令包括egrep、fgrep、rgrep
命令用法：
grep [选项] 匹配项 []表示可选参数
grep [选项[ [-e 匹配项]... [-f PATTERN]... PATTERN为正则表达式
命令概述：
grep在指定的文件中搜索包含PATTERN匹配的行。如果不指定文件或指定了“-”，则从标准输入中进行搜
索。 默认情况下，grep打印匹配的行。
此外，grep还有很多演变命令，如egrep、fgrep和rgpre，分别对应grep -E、grep -F和grep -r。
这些变种已经弃用，但他们被提供用作向后兼容。
命令参数：
1.匹配方式的选择
grep正则表达式（BRE、ERE、PCRE）
-E, --extended-regexp
将PATTERN作为扩展的正则表达式（ERE)
-F，--fixed-strings
将PATTERN作为为固定字符串的列表，由换行符分隔，匹配其中任意一个
-G, --basic-regexp
将PATTERN作为基本正则表达式（BRE），该选项为默认设置
-P，--perl-regexp
将PATTERN作为perl兼容正则表达式（PCRE)。
2.匹配控制
-e PATTERN, --regexp=PATTERN
将PATTERN作为匹配项，如果该选项被多次使用或和-f（--file）选项一起使用，匹配所有
的匹配项。该选项可以用来保护以'-'开头的匹配项。
-f FILE，--file=FILE
将FILE中的每行都作为匹配项，如果此选项被多次使用或与-e（--regexp）选项组合使用，搜索所有
给定的匹配项。空文件包含零个匹配项，因此不匹配任何内容
-i，--ignore-case
忽略匹配项的大小写
-v，--invert-match
反向匹配，选择没有匹配上的行
-w，--word-regexp
仅匹配完整单词，匹配的子字符串必须位于行的开头，或者前面有一个非字词字符。类似地，它必须位于
行尾或后面跟非字词组成字符（字词组成字符是字母、数字和下划线）。
-x，--line-regexp
仅选择与整行完全匹配的匹配项。对于正则表达式匹配项，这类似于将匹配项括起来，然后用^和$将其
包围。
-y 和-i作用相同，但已过时
3.通用输出控制
-c，--count
不打印匹配结果，而是打印匹配的行数
--color[=WHEN]，--colour[=WHEN]
将匹配到的字符串、行、上下文行、文件名、行号、字节偏移量和带转义符的分隔符（用于字段和上下文
行组）序列着色，颜色有环境变量GREP_COLORS决定，虽然GREP_COLOR已经过时，但grep依然支持该
环境变量，只不过优先权比GREP_COLORS低。WHEN可以为never、always和auto。相关环境变量介绍
：略。
-L，--files-without-match
不打印正常匹配结果，而是打印没有匹配上的文件的名称，扫描将在第一次匹配时停止。
-l，--files-with-matches
不打印正常匹配结果，而是打印匹配上的输入文件的名称，扫描将在第一次匹配时停止
-m NUM --max-count=NUM
在匹配到NUM行后停止读取文件
-o，--only-matching
仅打印匹配行中（非空的）匹配部分，每个部分在单独的输出行上
-q，--quiet，--silent
不向标准输出打印任何内容，匹配到内容立刻退出，即使检测到错误
-s，--no-messages
当文件不存在或文件不可读取时，不显示错误信息
4.输出行前缀控制
-b，--byte-offset
在每行输出之前，打印输入文件中基于0的字节偏移量。如果指定了-o（--only-matching），则打印
匹配项本身的偏移量
-H，--with-filename
打印每个匹配的文件名，当匹配到多个匹配项时，该选项为默认配置
-h，--no-filename
在输出中不显示文件名，只匹配到单个结果时，默认不显示文件名
--label=LABEL
将标准输入显示为来自文件标签的输入（？？？不理解）
-n，--line-number
显示行号
-T，--initial-tab
使匹配结果中每行的第一个字符位于制表位上，以便制表的对齐看起来显得正常。该选项对一些给输出内
容加前缀的选项很有作用：-H、-n和-b
-u，--unix-byt-offsets
报告Unix样式的字节偏移量，此开关使grep报告字节偏移量，就像文件是Unix样式的文本文件一样，即
去掉CR字符。这将产生与在Unix机器上运行grep相同的结果。除非同时使用-b选项，否则此选项无效，
它对MS-DOS和MS Windows以外的平台没有影响。
-Z，--null
将文件名后面的符号（冒号或回车）改为零字节（ASCII NUL 字符），例如，grep -lZ在每个文件名
后输出一个零字节，而不是通常的换行。此选项使输出明确，甚至如果文件名包含不寻常的字符，如新行。
此选项可与其他命令一起使用，如find -print0、perl-0、sort-z和xargs-0来处理任意文件名，
甚至包含换行符的文件名。
5.上下文行控制
-A NUM，--after-context=NUM
在匹配行之后打印下文的NUM行,连续的匹配组之间用分隔符“--”隔开。和-o或--only-matching选项
一起使用时，该选项没有任何效果，并且会发出警告
-B NUM，--before-context=NUM
在匹配行的前面打印上文的NUM行，,连续的匹配组之间用分隔符“--”隔开。和-o或--only-matching
选项一起使用时，该选项没有任何效果，并且会发出警告
-C NUM，-NUM，--context=NUM
打印匹配行的上下文各NUM行，连续的匹配组之间用分隔符“--”隔开。和-o或--only-matching选项
一起使用时，该选项没有任何效果，并且会发出警告
6.文件及目录的选择
-a，--text
像处理文本一样处理二进制文件，相当于--binary-files=text选项
--binary-files=TYPE
如果文件的前几个字节指示该文件包含二进制数据，则假定文件的类型为TYEP。默认情况下，TYPE为
binary，grep通常只输出一行表示二进制文件匹配的消息，或者因为没有匹配结果而没有输出；如果
TYPE为without-match，则grep不对二进制文件进行匹配，相当于-I选项；如果TYPE为text，grep
将二进制文件当作文本文件处理，这相当于-a选项，处理二进制数据时，grep可以将非文本字节视为行
终止符，例如，模式“.”（句点）可能不能匹配空字节，因为空字节可能被视为行终止符。警告：grep
--binary-files=text可能输出二进制垃圾，如果输出是终端且终端驱动程序将其中一些文本解释为
命令则可能会产生严重的副作用。
-D ACTION，--devices=ACTION
如果输入文件是一个设备、FIFO或则套接字，使用ACTION去处理它，ACTION默认为read，意味着该文
件将被当作普通文件进行读取。如果ACTION为skip，设备文件被忽略。
-d ACTION，--directories=ACTION
如果输入文件为一个目录，使用ACTION处理它。ACTION默认为read，即将目录作为普通文件处理。如果
ACTION为skip，跳过该目录。如果ACTION为recurse，递归读取目录下的所有文件，并且遵循命令行
符号链接，相当于-r选项
--exclude=GLOB
跳过名称与GLOB匹配的文件（使用通配符匹配），文件名glob可以使用*、？、和[…]作为通配符，并逐
字引用通配符或反斜杠字符。
--exclude-from=FILE
跳过其基名称与从FILE读取的任意文件名通过glob匹配的文件（使用通配符匹配，如--exclude下所述）
--exclude-dir=DIR
从递归搜索中排除与DIR匹配的目录
-I
处理二进制文件，就像它不包含匹配的数据一样，这相当于--binary-files=without-match选项。
--include=GLOB
搜索名称与从GLOB匹配的文件（使用通配符匹配，如--exclude下所述）
-r，--recursive
递归读取目录下的所有文件，并且遵循命令行符号链接。如果没有给定文件操作数，grep将搜索当前工作
目录。该命令相当于-d recurse选项
-R，--dereference-recursive
递归读取目录下所有文件，遵循所有符号链接
7.其他选项
--line-buffered
在输出上使用行缓冲，这可能会导致性能下降
-U，--binary
将文件视为二进制文件，默认情况下，在MS-DOS和MS-Window中，grep通过读取文件前32KB的内容决
定这个文件的类型，如果文件为文本文件，grep从原始文件中删除CR字符（使带有‘^'和’$'的正则表达
式能正常工作），指定-U可以让其对文件进行逐字读取。如果文件为文本文件，每行末尾有CR/LF，这将
造成一些正则表达式失效。该选项对MS-DOS和MS-Windows以外的平台无影响。
-z，--null-data
将输入视为一组行，每个行以零字节（ASCII NUL字符）而不是换行符终止，与-Z或--null选项类似，
此选项可以与sort -z等命令一起使用，以处理任意文件名。
8.通用信息
--help
显示帮助信息
--version
显示版本信息
示例：
1. grep PATTERN…
grep的第一种用法 ，不带任何参数，根据匹配项PATTERN进行匹配。
xiaohui@ubuntu:~/work/grep_learn$ ls | grep .c
grep_test_2.c
grep_test_3.c
grep_test.c
xiaohui@ubuntu:~/work/grep_learn$
通过管道，grep，可以从其他命令的输出中查找匹配项。
2. grep PATTERN… FILE…
grep的第二种用法 ，不带任何参数，根据匹配项进行匹配。
xiaohui@ubuntu:~/work/grep_learn$ cat grep_test.c
iigrep....
learn
text
xiaohui@ubuntu:~/work/grep_learn$ grep text ./grep_test.c
text
xiaohui@ubuntu:~/work/grep_learn$
3. grep -E/-G PATTERN…
由于在grep中，基本正则表达式和扩展正则表达式在使用时的区别在于：在基本正则表达式中，元字符？、+、{、|、(、和)失去了特殊意义，需要使用反斜杠版本\？、+、{、|、(、和\）。如果不加任何匹配方式的选项，默认为-G，即基本正则表达式。
xiaohui@ubuntu:~/work/grep_learn$ cat grep_test_2.c
apple
banana
cat
dog
egg
fire
glof
12
34
56
78
90
xiaohui@ubuntu:~/work/grep_learn$ grep -G grep_test_2.c
apple
banana
cat
dog
egg
fire
glof
xiaohui@ubuntu:~/work/grep_learn$ grep -G grep_test_2.c
xiaohui@ubuntu:~/work/grep_learn$
4. grep -F PATTERN…
将PATTERN作为固定字符串形式的匹配项，不识别正则表达式。
xiaohui@ubuntu:~/work/grep_learn$ cat grep_test.c
^abc
abc
efg$
efg
text*
textxx
headxxxxend
headaaaaend
head*end
xiaohui@ubuntu:~/work/grep_learn$ grep ^abc grep_test.c
abc
xiaohui@ubuntu:~/work/grep_learn$ grep -F ^abc grep_test.c
^abc
xiaohui@ubuntu:~/work/grep_learn$ grep efg$ grep_test.c
efg
xiaohui@ubuntu:~/work/grep_learn$ grep -F efg$ grep_test.c
efg$
xiaohui@ubuntu:~/work/grep_learn$ greptext* grep_test.c
text*
textxx
xiaohui@ubuntu:~/work/grep_learn$ grep -Ftext* grep_test.c
text*
xiaohui@ubuntu:~/work/grep_learn$
5. grep -e PATTERN… 和grep -f FILE…
-e的作用和不加参数时类似，唯一区别是可以保护以‘-’开头的匹配项
xiaohui@ubuntu:~/work/grep_learn$ grep -e -* grep_test.c
^abc
abc
efg$
efg
text*
textxx
headxxxxend
headaaaaend
head*end
-test //-符号标红
test
xiaohui@ubuntu:~/work/grep_learn$ grep -test grep_test.c
grep: invalid option -- 't'
Usage: grep ... PATTERN ...
Try 'grep --help' for more information.
xiaohui@ubuntu:~/work/grep_learn$ grep -e -test grep_test.c
-test
xiaohui@ubuntu:~/work/grep_learn$
-e选项可以多次使用，匹配更多的内容
xiaohui@ubuntu:~/work/grep_learn$ grep -e -test -e test grep_test.c
-test
test
xiaohui@ubuntu:~/work/grep_learn$
-f的作用是将FILE中的每行都作为匹配项，和-e一样可以多次使用
xiaohui@ubuntu:~/work/grep_learn$ grep -f grep_file.c grep_*.c
grep_file.c:test
grep_file.c:text
grep_file.c:head
grep_file.c:end
grep_test_2.c:text_2
grep_test_2.c:test_2
grep_test_3.c:text_3
grep_test_3.c:test_3
grep_test.c:text*
grep_test.c:textxx
grep_test.c:headxxxxend
grep_test.c:headaaaaend
grep_test.c:head*end
grep_test.c:-test
grep_test.c:test
xiaohui@ubuntu:~/work/grep_learn$ cat grep_file.c
test
text
head
end
xiaohui@ubuntu:~/work/grep_learn$ echo > grep_file_2.c
xiaohui@ubuntu:~/work/grep_learn$ grep -f grep_file_2.c -f grep_file.c grep_*.c
grep_file_2.c:
grep_file.c:test
grep_file.c:text
grep_file.c:head
grep_file.c:end
grep_test_2.c:apple
grep_test_2.c:banana
grep_test_2.c:cat
grep_test_2.c:text_2
grep_test_2.c:test_2
grep_test_3.c:text_3
grep_test_3.c:test_3
grep_test.c:^abc
grep_test.c:abc
grep_test.c:text*
grep_test.c:textxx
grep_test.c:headxxxxend
grep_test.c:headaaaaend
grep_test.c:head*end
grep_test.c:-test
grep_test.c:test
xiaohui@ubuntu:~/work/grep_learn$
-e和-f也可以同时使用，匹配所有匹配项。
xiaohui@ubuntu:~/work/grep_learn$ grep -f grep_file.c -e test grep_test.c
text*
textxx
headxxxxend
headaaaaend
head*end
-test
test
xiaohui@ubuntu:~/work/grep_learn$ cat grep_file.c
test
text
head
end
xiaohui@ubuntu:~/work/grep_learn$
6. grep -i PATTERN…
忽略匹配项PATTERN的大小写
xiaohui@ubuntu:~/work/grep_learn$ grep -i test grep_test.c
TEST
-test
test
xiaohui@ubuntu:~/work/grep_learn$ grep test grep_test.c
-test
test
xiaohui@ubuntu:~/work/grep_learn$
7. grep -v PATTERN…
反向匹配
xiaohui@ubuntu:~/work/grep_learn$ grep test grep_test.c
-test
test
xiaohui@ubuntu:~/work/grep_learn$ grep -v test grep_test.c
^abc
abc
efg$
efg
text*
textxx
TEXT
TEST
xiaohui@ubuntu:~/work/grep_learn$
8. grep -w PATTERN…
匹配完整的单词，单词前后不能有其他字母或数字，但允许单词前面有非字词符号。
xiaohui@ubuntu:~/work/grep_learn$ grep test grep_test_3.c
xxtest
testxx
_test
-test
test_3
test
test_
xxx xxxtest-
This is a test file.
xiaohui@ubuntu:~/work/grep_learn$ grep -w test grep_test_3.c
-test
test
xxx xxxtest-
This is a test file.
xiaohui@ubuntu:~/work/grep_learn$
9. grep -x PATTERN…
整行匹配
xiaohui@ubuntu:~/work/grep_learn$ grep test grep_test_3.c
xxtest
testxx
_test
-test
test_3
test
test_
xxx xxxtest-
This is a test file.
xiaohui@ubuntu:~/work/grep_learn$ grep "This is a test file" grep_test_3.c
This is a test file.
xiaohui@ubuntu:~/work/grep_learn$
10. grep -c PATTERN…
打印匹配的行数（不是行号），而不打印匹配内容
xiaohui@ubuntu:~/work/grep_learn$ grep test grep_test_3.c
xxtest
testxx
_test
-test
test_3
test test test
test_
xxx xxxtest-
This is a test file.
xiaohui@ubuntu:~/work/grep_learn$ grep test -c grep_test_3.c
9
xiaohui@ubuntu:~/work/grep_learn$
11. grep -color[=WHEN] PATTERN…
匹配结果颜色设置，ubuntu默认用红色进行标识
12. grep -L PATTERN…
不打印匹配的内容，打印FILE中没有匹配上的文件
xiaohui@ubuntu:~/work/grep_learn$ grep "test" grep_*.c
grep_file.c:test
grep_test_2.c:test_2
grep_test_3.c:xxtest
grep_test_3.c:testxx
grep_test_3.c:_test
grep_test_3.c:-test
grep_test_3.c:test_3
grep_test_3.c:test test test
grep_test_3.c:test_
grep_test_3.c:xxx xxxtest-
grep_test_3.c:This is a test file.
grep_test.c:-test
grep_test.c:test
xiaohui@ubuntu:~/work/grep_learn$ grep "test" grep_*.c -L
grep_file_2.c
xiaohui@ubuntu:~/work/grep_learn$
13. grep -l PATTERN…
不打印匹配的内容，而是打印FILE中匹配上的文件的名称
xiaohui@ubuntu:~/work/grep_learn$ grep "test" grep_*.c
grep_file.c:test
grep_test_2.c:test_2
grep_test_3.c:xxtest
grep_test_3.c:testxx
grep_test_3.c:_test
grep_test_3.c:-test
grep_test_3.c:test_3
grep_test_3.c:test test test
grep_test_3.c:test_
grep_test_3.c:xxx xxxtest-
grep_test_3.c:This is a test file.
grep_test.c:-test
grep_test.c:test
xiaohui@ubuntu:~/work/grep_learn$ grep "test" grep_*.c -l
grep_file.c
grep_test_2.c
grep_test_3.c
grep_test.c
xiaohui@ubuntu:~/work/grep_learn$
14. grep -m NUM PATTERN…
每个文件最多匹配出NUM行，
xiaohui@ubuntu:~/work/grep_learn$ grep "test" grep_test_3.c -m 5
xxtest
testxx
_test
-test
test_3
xiaohui@ubuntu:~/work/grep_learn$ grep "test" grep_test_3.c
xxtest
testxx
_test
-test
test_3
test test test
test_
xxx xxxtest-
This is a test file.
xiaohui@ubuntu:~/work/grep_learn$ grep "test" grep_*.c -m 3
grep_file.c:test
grep_test_2.c:test_2
grep_test_3.c:xxtest
grep_test_3.c:testxx
grep_test_3.c:_test
grep_test.c:-test
grep_test.c:test
xiaohui@ubuntu:~/work/grep_learn$
15. grep -o PATTERN…
仅打印匹配的内容，而不是匹配的一整行
xiaohui@ubuntu:~/work/grep_learn$ grep "test" grep_test_3.c
xxtest
testxx
_test
-test
test_3
test test test
test_
xxx xxxtest-
This is a test file.
xiaohui@ubuntu:~/work/grep_learn$ grep "test" grep_test_3.c -o
test
test
test
test
test
test
test
test
test
test
test
xiaohui@ubuntu:~/work/grep_learn$
16. grep -q PATTERN…
不显示匹配结果，匹配结束立刻退出
xiaohui@ubuntu:~/work/grep_learn$ grep "test" grep_test_3.c
xxtest
testxx
_test
-test
test_3
test test test
test_
xxx xxxtest-
This is a test file.
xiaohui@ubuntu:~/work/grep_learn$ grep "test" grep_test_3.c -q
xiaohui@ubuntu:~/work/grep_learn$
17. grep -s PATTERN…
不显示文件不存在和读取失败的错误信息
xiaohui@ubuntu:~/work/grep_learn$ grep test file.c
grep: file.c: No such file or directory
xiaohui@ubuntu:~/work/grep_learn$ grep test file.c -s
xiaohui@ubuntu:~/work/grep_learn$
xiaohui@ubuntu:~/work/grep_learn$ grep test /root/*
grep: /root/*: Permission denied
xiaohui@ubuntu:~/work/grep_learn$ grep test /root/* -s
xiaohui@ubuntu:~/work/grep_learn$
18. grep -b PATTERN…
打印匹配项基于文件开头的偏移量
19. grep -H PATTERN…
打印匹配项所在文件的文件名，匹配结果多于一个文件时，默认显示文件名。
20. grep -h PATTERN…
不显示文件名，单个文件匹配时，默认不显示文件名
xiaohui@ubuntu:~/work/grep_learn$ grep "test" grep_test_3.c
xxtest
testxx
_test
-test
test_3
test test test
test_
xxx xxxtest-
This is a test file.
xiaohui@ubuntu:~/work/grep_learn$ grep "test" grep_test*.c
grep_test_2.c:test_2
grep_test_3.c:xxtest
grep_test_3.c:testxx
grep_test_3.c:_test
grep_test_3.c:-test
grep_test_3.c:test_3
grep_test_3.c:test test test
grep_test_3.c:test_
grep_test_3.c:xxx xxxtest-
grep_test_3.c:This is a test file.
grep_test.c:-test
grep_test.c:test
xiaohui@ubuntu:~/work/grep_learn$ grep "test" grep_test*.c -h
test_2
xxtest
testxx
_test
-test
test_3
test test test
test_
xxx xxxtest-
This is a test file.
-test
test
xiaohui@ubuntu:~/work/grep_learn$
21. grep -n PATTERN…
显示匹配项在文件中的行号
22. grep -T PATTERN…
显示时使用制表符
xiaohui@ubuntu:~/work/grep_learn$ grep "test" grep_test*.c -n -H -b
grep_test_2.c:14:57:test_2
grep_test_3.c:1:0:xxtest
grep_test_3.c:2:7:testxx
grep_test_3.c:3:14:_test
grep_test_3.c:4:20:-test
grep_test_3.c:5:26:test_3
grep_test_3.c:6:33:test test test
grep_test_3.c:7:48:test_
grep_test_3.c:8:54:xxx xxxtest-
grep_test_3.c:9:69:This is a test file.
grep_test.c:9:41:-test
grep_test.c:10:47:test
xiaohui@ubuntu:~/work/grep_learn$ grep "test" grep_test*.c -n -H -b -T
grep_test_2.c:14: 57 :test_2
grep_test_3.c: 1: 0 :xxtest
grep_test_3.c: 2: 7 :testxx
grep_test_3.c: 3: 14 :_test
grep_test_3.c: 4: 20 :-test
grep_test_3.c: 5: 26 :test_3
grep_test_3.c: 6: 33 :test test test
grep_test_3.c: 7: 48 :test_
grep_test_3.c: 8: 54 :xxx xxxtest-
grep_test_3.c: 9: 69 :This is a test file.
grep_test.c: 9: 41:-test
grep_test.c:10: 47:test
xiaohui@ubuntu:~/work/grep_learn$
23. grep -Z PATTERN…
文件名后面的符号改为零字节（ASCII NUL字符）
xiaohui@ubuntu:~/work/grep_learn$ grep test grep_test.c -H
grep_test.c:-test
grep_test.c:test
xiaohui@ubuntu:~/work/grep_learn$ grep test grep_test.c -H -Z
grep_test.c-test
grep_test.ctest
xiaohui@ubuntu:~/work/grep_learn$ grep test grep_test* -Z -H -l
grep_test_2.cgrep_test_3.cgrep_test.cxiaohui@ubuntu:~/work/grep_learn$
24. grep -A NUM PATTERN…
将匹配行后面的NUM行也打印出来
xiaohui@ubuntu:~/work/grep_learn$ grep TEST -A 0 grep_test.c
TEST
xiaohui@ubuntu:~/work/grep_learn$ grep TEST -A 1 grep_test.c
TEST
-test
xiaohui@ubuntu:~/work/grep_learn$ grep TEST -A 2 grep_test.c
TEST
-test
test
xiaohui@ubuntu:~/work/grep_learn$ grep TEST -A 3 grep_test.c
TEST
-test
test
xiaohui@ubuntu:~/work/grep_learn$
25. grep -B NUM PATTERN…
将匹配行前面的NUM行也打印出来
xiaohui@ubuntu:~/work/grep_learn$ grep test grep_test_2.c -B 0
test_2
xiaohui@ubuntu:~/work/grep_learn$ grep test grep_test_2.c -B 1
text_2
test_2
xiaohui@ubuntu:~/work/grep_learn$ grep test grep_test_2.c -B 2
90
text_2
test_2
xiaohui@ubuntu:~/work/grep_learn$ grep test grep_test_2.c -B -1
grep: -1: invalid context length argument
xiaohui@ubuntu:~/work/grep_learn$
26. grep -C NUM PATTERN…
将匹配行前面和后面的NUM行也打印出来
xiaohui@ubuntu:~/work/grep_learn$ grep TEXT grep_test.c -C 0
TEXT
xiaohui@ubuntu:~/work/grep_learn$ grep TEXT grep_test.c -C 1
textxx
TEXT
TEST
xiaohui@ubuntu:~/work/grep_learn$ grep TEXT grep_test.c -C 2
text*
textxx
TEXT
TEST
-test
xiaohui@ubuntu:~/work/grep_learn$ grep TEXT grep_test.c -C 3
efg
text*
textxx
TEXT
TEST
-test
test
xiaohui@ubuntu:~/work/grep_learn$
27. grep -a PATTERN…
将二进制文件当做文本文件来处理。
下图中hello_grep.out为二进制文件（可执行文件），不加-a参数，grep会提示二进制文件无法进行匹配。
28. grep --binary-files=TYPE PATTERN…
TYPE的值可以为：binary（默认）、without-match、text，binary和without-match的区别是前者使用时会提示二进制文件无法匹配，后者不会提示，–binary-files=text相当于-a选项。
xiaohui@ubuntu:~/work/grep_learn$ grep hello hello_grep.out --binary-files=without-match
xiaohui@ubuntu:~/work/grep_learn$ grep hello hello_grep.out --binary-files=binary
Binary file hello_grep.out matches
xiaohui@ubuntu:~/work/grep_learn$ grep hello hello_grep.out --binary-files=text
29. grep -D ACTION PATTERN…
当FILE为设备文件、FIFO或套接字时，使用ACTION去处理它，ACTION默认为read，也可以为skip，前者将该文件作为普通文件处理，后者则跳过读取该文件。
先用mkfifo创建一个fifo件，将test字符串在后台写入：
xiaohui@ubuntu:~/work/grep_learn$ echo test > my_fifo &
11012
xiaohui@ubuntu:~/work/grep_learn$ grep test my_fifo -D read
test
+Done echo test > my_fifo
xiaohui@ubuntu:~/work/grep_learn$ echo test > my_fifo &
11015
xiaohui@ubuntu:~/work/grep_learn$ grep test my_fifo -D skip
xiaohui@ubuntu:~/work/grep_learn$ jobs
+Broken pipe echo test > my_fifo
xiaohui@ubuntu:~/work/grep_learn$
30. grep -d ACTION PATTERN…
当FILE为目录时，使用ACTION去处理它，ACTION默认为read，也可以为skip或recurse，ACTION为read时，grep将该文件作为普通文件处理，为skip时跳过读取该文件，为recurse时，递归读取所有文件。
xiaohui@ubuntu:~/work/grep_learn$ grep text dir/
grep: dir/: Is a directory
xiaohui@ubuntu:~/work/grep_learn$ grep text dir/ -d read
grep: dir/: Is a directory
xiaohui@ubuntu:~/work/grep_learn$ grep text dir/ -d skip
xiaohui@ubuntu:~/work/grep_learn$ grep text dir/ -d recurse
dir/grep_test.c:text_0
dir/dir1/grep_test.c:text_1
dir/dir2/grep_test.c:text_2
xiaohui@ubuntu:~/work/grep_learn$
31. grep --exclude=GLOB PATTERN…
跳过与GLOB匹配的文件，文件名可以使用通配符
xiaohui@ubuntu:~/work/grep_learn$ grep test --exclude=grep_test_3.c grep_test*.cgrep_test_2.c:test_2
grep_test.c:-test
grep_test.c:test
xiaohui@ubuntu:~/work/grep_learn$ grep test grep_test*.cgrep_test_2.c:test_2
grep_test_3.c:xxtest
grep_test_3.c:testxx
grep_test_3.c:_test
grep_test_3.c:-test
grep_test_3.c:test_3
grep_test_3.c:test test test
grep_test_3.c:test_
grep_test_3.c:xxx xxxtest-
grep_test_3.c:This is a test file.
grep_test.c:-test
grep_test.c:test
xiaohui@ubuntu:~/work/grep_learn$
<
32. grep --exclude-from=FILE PATTERN…
从FILE（要匹配的文件）中排除与FILE（–exclude-from=选项中的FILE）文件内容匹配的文件
grep_test_4.c中有grep_test_3*，所以匹配时排除文件名与grep_test_3*匹配的文件
xiaohui@ubuntu:~/work/grep_learn$ cat grep_test_4.c
xxxx
grep_test_3*
xiaohui@ubuntu:~/work/grep_learn$ grep test --exclude-from=grep_test_4.c grep_test*.c
grep_test_2.c:test_2
grep_test_4.c:grep_test_3*
grep_test.c:-test
grep_test.c:test
xiaohui@ubuntu:~/work/grep_learn$ grep testgrep_test*.cgrep_test_2.c:test_2
grep_test_3.c:xxtest
grep_test_3.c:testxx
grep_test_3.c:_test
grep_test_3.c:-test
grep_test_3.c:test_3
grep_test_3.c:test test test
grep_test_3.c:test_
grep_test_3.c:xxx xxxtest-
grep_test_3.c:This is a test file.
grep_test_4.c:grep_test_3*
grep_test.c:-test
grep_test.c:test
xiaohui@ubuntu:~/work/grep_learn$
33. grep --exclude-dir=DIR PATTERN…
从FILE（目录文件）中排除目录名/文件名与DIR匹配的文件
xiaohui@ubuntu:~/work/grep_learn$ grep text --exclude-dir=dir ./ -r
./grep_test.c:text*
./grep_test.c:textxx
./grep_file.c:text
./text_0/grep_test.c:text_0
./text_1/grep_test.c:text_0
./grep_test_2.c:text_2
Binary file ./hello_grep.out matches
xiaohui@ubuntu:~/work/grep_learn$ grep text./ -r
./grep_test.c:text*
./grep_test.c:textxx
./grep_file.c:text
./text_0/grep_test.c:text_0
./text_1/grep_test.c:text_0
./grep_test_2.c:text_2
Binary file ./hello_grep.out matches
./dir/grep_test.c:text_0
./dir/dir1/grep_test.c:text_1
./dir/dir2/grep_test.c:text_2
xiaohui@ubuntu:~/work/grep_learn$
34. grep -I PATTERN…
同–binary-files=without-match，见28.grep --binary-files。
35. grep --include=GLOB PATTERN…
搜索文件名与GLOB匹配的文件（使用通配符匹配）
xiaohui@ubuntu:~/work/grep_learn$ grep test --include=grep_test_2* grep_test_*.c
grep_test_2.c:test_2
xiaohui@ubuntu:~/work/grep_learn$ grep test --include=grep_test_4* grep_test_*.c
grep_test_4.c:grep_test_3*
xiaohui@ubuntu:~/work/grep_learn$
36. grep -r PATTERN…
同-d recurse选项，默认所在当前工作目录，遵循命令行符号链接，见30.grep -d ACTION。
37. grep -R PATTERN…
和-r类似，但遵循所有的符号链接
.
1
man手册
以下为 grep 命令手册原文：
GREP(1) General Commands Manual GREP(1)
NAME
grep, egrep, fgrep, rgrep - print lines matching a pattern
SYNOPSIS
grep PATTERN
grep [-e PATTERN]...[-f FILE]...
DESCRIPTION
grep searches the named input FILEs for lines containing a match to the
given PATTERN.If no files are specified, or if the file “-” is given,
grepsearchesstandardinput. By default, grep prints the matching
lines.
In addition, the variant programs egrep, fgrep and rgrep arethesame
asgrep -E,grep -F,andgrep -r, respectively.These variants are
deprecated, but are provided for backward compatibility.
OPTIONS
Generic Program Information
--help Output a usage message and exit.
-V, --version
Output the version number of grep and exit.
Matcher Selection
-E, --extended-regexp
Interpret PATTERN as an extended regularexpression(ERE,see
below).
-F, --fixed-strings
Interpret PATTERN as a list of fixed strings (instead of regular
expressions), separated by newlines,anyofwhichistobe
matched.
-G, --basic-regexp
InterpretPATTERNasabasicregularexpression(BRE, see
below).This is the default.
-P, --perl-regexp
Interpret the pattern as aPerl-compatibleregularexpression
(PCRE). Thisishighlyexperimental and grep -P may warn of
unimplemented features.
Matching Control
-e PATTERN, --regexp=PATTERN
Use PATTERN as the pattern.If thisoptionisusedmultiple
times or is combined with the -f (--file) option, search for all
patterns given.This option can be used toprotectapattern
beginning with “-”.
-f FILE, --file=FILE
Obtain patterns from FILE, one per line.If this option is used
multiple times or is combined withthe-e(--regexp)option,
searchforallpatternsgiven.The empty file contains zero
patterns, and therefore matches nothing.
-i, --ignore-case
Ignore case distinctions inboththePATTERNandtheinput
files.
-v, --invert-match
Invert the sense of matching, to select non-matching lines.
-w, --word-regexp
Selectonlythoselinescontainingmatchesthat form whole
words.The test is that the matching substring musteitherbe
atthebeginningoftheline,orprecededbya non-word
constituent character.Similarly, it must be either at theend
ofthelineorfollowed by a non-word constituent character.
Word-constituentcharactersareletters,digits, and the
underscore.
-x, --line-regexp
Selectonlythosematchesthat exactly match the whole line.
For a regular expression pattern, thisislikeparenthesizing
the pattern and then surrounding it with ^ and $.
-y Obsolete synonym for -i.
General Output Control
-c, --count
Suppressnormal output; instead print a count of matching lines
for each input file.With the -v,--invert-matchoption(see
below), count non-matching lines.
--color[=WHEN], --colour[=WHEN]
Surround thematched(non-empty)strings,matchinglines,
context lines, filenames,linenumbers,byteoffsets,and
separators(for fields and groups of context lines) with escape
sequences to display them in color on the terminal.Thecolors
aredefinedbytheenvironmentvariableGREP_COLORS. The
deprecated environment variable GREP_COLOR isstillsupported,
butits setting does not have priority.WHEN is never, always,
or auto.
-L, --files-without-match
Suppress normal output; instead print thenameofeachinput
file from which no output would normally have been printed.The
scanning will stop on the first match.
-l, --files-with-matches
Suppress normal output; instead print thenameofeachinput
filefromwhichoutput would normally have been printed.The
scanning will stop on the first match.
-m NUM, --max-count=NUM
Stop reading a file after NUM matching lines.If theinputis
standardinputfrom a regular file, and NUM matching lines are
output, grep ensures that the standard inputispositionedto
justafter the last matching line before exiting, regardless of
the presence of trailing context lines.This enables acalling
processto resume a search.When grep stops after NUM matching
lines, it outputs any trailing context lines.Whenthe-cor
--countoptionisalsoused,grepdoesnot output a count
greater than NUM.When the -v or --invert-match option isalso
used, grep stops after outputting NUM non-matching lines.
-o, --only-matching
Printonlythematched(non-empty) parts of a matching line,
with each such part on a separate output line.
-q, --quiet, --silent
Quiet;donotwriteanythingtostandard output. Exit
immediatelywithzero status if any match is found, even if an
error was detected.Also see the -s or --no-messages option.
-s, --no-messages
Suppress error messages about nonexistent or unreadable files.
Output Line Prefix Control
-b, --byte-offset
Print the 0-based byte offset within the input file beforeeach
line of output.If -o (--only-matching) is specified, print the
offset of the matching part itself.
-H, --with-filename
Print the file name for each match.This isthedefaultwhen
there is more than one file to search.
-h, --no-filename
Suppresstheprefixingoffile names on output.This is the
default when there is only one file (or only standard input)to
search.
--label=LABEL
Displayinputactuallycomingfromstandardinput as input
comingfromfileLABEL. Thisisespeciallyuseful when
implementingtoolslikezgrep,e.g.,gzip -cd foo.gz | grep
--label=foo -H something.See also the -H option.
-n, --line-number
Prefix each line of output with the 1-based linenumberwithin
its input file.
-T, --initial-tab
Makesurethat the first character of actual line content lies
on a tab stop, so that the alignment of tabs looks normal.This
isusefulwithoptions that prefix their output to the actual
content: -H,-n, and -b.In ordertoimprovetheprobability
that lines from a single file will all start at the same column,
this also causes the line number and byte offset (if present) to
be printed in a minimum size field width.
-u, --unix-byte-offsets
ReportUnix-stylebyteoffsets. Thisswitch causes grep to
report byte offsets as if the file were a Unix-style textfile,
i.e.,withCRcharactersstrippedoff. Thiswill produce
results identical to runninggreponaUnixmachine. This
optionhasnoeffect unless -b option is also used; it has no
effect on platforms other than MS-DOS and MS-Windows.
-Z, --null
Output a zero byte (the ASCIINULcharacter)insteadofthe
characterthat normally follows a file name.For example, grep
-lZ outputs a zero byte after eachfilenameinsteadofthe
usualnewline. This option makes the output unambiguous, even
in the presence of file names containing unusual characters like
newlines. Thisoptioncanbeusedwith commands like find
-print0, perl -0, sort -z, and xargs-0toprocessarbitrary
file names, even those that contain newline characters.
Context Line Control
-A NUM, --after-context=NUM
PrintNUMlinesoftrailingcontextaftermatching lines.
Placesalinecontainingagroupseparator(--) between
contiguousgroupsofmatches.With the -o or --only-matching
option, this has no effect and a warning is given.
-B NUM, --before-context=NUM
Print NUMlinesofleadingcontextbeforematchinglines.
Places alinecontainingagroupseparator(--)between
contiguous groups of matches.With the-oor--only-matching
option, this has no effect and a warning is given.
-C NUM, -NUM, --context=NUM
PrintNUMlines of output context.Places a line containing a
group separator (--) between contiguous groups of matches.With
the-oor--only-matchingoption,thishas no effect and a
warning is given.
File and Directory Selection
-a, --text
Process a binary file as if it were text; this is equivalentto
the --binary-files=text option.
--binary-files=TYPE
If the first few bytes of a file indicate that the file contains
binary data, assume that the file is of type TYPE.Bydefault,
TYPEisbinary,andgrepnormally outputs either a one-line
message saying that a binary filematches,ornomessageif
thereis no match.If TYPE is without-match, grep assumes that
a binary file does not match;thisisequivalenttothe-I
option. If TYPE is text, grep processes a binary file as if it
were text; this is equivalent to the -a option.When processing
binarydata, grep may treat non-text bytes as line terminators;
for example, the pattern '.' (period) mightnotmatchanull
byte,asthenull byte might be treated as a line terminator.
Warning: grep --binary-files=text might outputbinarygarbage,
whichcanhavenasty side effects if the output is a terminal
and if the terminal driver interprets some of it as commands.
-D ACTION, --devices=ACTION
If an input file is a device, FIFOorsocket,useACTIONto
processit. Bydefault,ACTIONisread,which means that
devices are read just as if they were ordinary files.If ACTION
is skip, devices are silently skipped.
-d ACTION, --directories=ACTION
Ifaninput file is a directory, use ACTION to process it.By
default, ACTION is read, i.e., read directories just as ifthey
were ordinary files. IfACTIONisskip,silentlyskip
directories.If ACTION is recurse, read allfilesundereach
directory,recursively,followingsymbolic links only if they
are on the command line.This is equivalent to the -r option.
--exclude=GLOB
SkipfileswhosebasenamematchesGLOB(using wildcard
matching). Afile-nameglobcanuse*,?,and [...]as
wildcards, and \ to quoteawildcardorbackslashcharacter
literally.
--exclude-from=FILE
Skipfileswhosebase name matches any of the file-name globs
read from FILE(usingwildcardmatchingasdescribedunder
--exclude).
--exclude-dir=DIR
ExcludedirectoriesmatchingthepatternDIR from recursive
searches.
-I Process a binary file as if it did notcontainmatchingdata;
this is equivalent to the --binary-files=without-match option.
--include=GLOB
Searchonlyfiles whose base name matches GLOB (using wildcard
matching as described under --exclude).
-r, --recursive
Read all filesundereachdirectory,recursively,following
symboliclinks only if they are on the command line.Note that
ifnofileoperandisgiven,grepsearchesthe working
directory.This is equivalent to the -d recurse option.
-R, --dereference-recursive
Readallfilesunder each directory, recursively.Follow all
symbolic links, unlike -r.
Other Options
--line-buffered
Use line buffering on output. Thiscancauseaperformance
penalty.
-U, --binary
Treatthefile(s) as binary.By default, under MS-DOS and MS-
Windows, grep guesses the file type by looking atthecontents
ofthe first 32KB read from the file.If grep decides the file
is a text file, it strips the CR charactersfromtheoriginal
filecontents(tomakeregular expressions with ^ and $ work
correctly).Specifying -U overrules this guesswork, causing all
filesto be read and passed to the matching mechanism verbatim;
if the file is a text file with CR/LF pairs at the endofeach
line,thiswillcause some regular expressions to fail.This
option has no effect on platformsotherthanMS-DOSandMS-
Windows.
-z, --null-data
Treattheinputasa set of lines, each terminated by a zero
byte (the ASCII NUL character) instead of a newline. Likethe
-Zor --null option, this option can be used with commands like
sort -z to process arbitrary file names.
REGULAR EXPRESSIONS
A regular expression is a pattern thatdescribesasetofstrings.
Regular expressions are constructed analogouslytoarithmetic
expressions, by using various operators to combine smaller expressions.
grep understands three different versions of regular expression syntax:
“basic”(BRE), “extended” (ERE) and “perl” (PCRE).In GNU grep, there
is no difference in available functionality between basic andextended
syntaxes.In other implementations, basic regular expressions are less
powerful. Thefollowingdescriptionappliestoextendedregular
expressions;differencesfor basic regular expressions are summarized
afterwards. Perl-compatibleregularexpressions give additional
functionality,and are documented in pcresyntax(3) and pcrepattern(3),
but work only if PCRE is available in the system.
The fundamental building blocks are the regular expressions thatmatch
a single character.Most characters, including all letters and digits,
are regular expressions that match themselves.Any meta-character with
special meaning may be quoted by preceding it with a backslash.
The period . matches any single character.
Character Classes and Bracket Expressions
Abracketexpression is a list of characters enclosed by [ and ].It
matches any single character in that list; if thefirstcharacterof
thelist is the caret ^ then it matches any character not in the list.
For example, the regular expressionmatchesanysingle
digit.
Withinabracketexpression,arangeexpressionconsistsof two
characters separated by a hyphen.It matches any single character that
sortsbetweenthetwocharacters,inclusive,usingthelocale's
collating sequence and character set.For example, inthedefaultC
locale, is equivalent to .Many locales sort characters in
dictionaryorder,andintheselocalesistypically not
equivalent to ; it might be equivalent to , for example.
To obtain the traditional interpretation ofbracketexpressions,you
canuse the C locale by setting the LC_ALL environment variable to the
value C.
Finally, certain named classesofcharactersarepredefinedwithin
bracket expressions, as follows.Their names are self explanatory, and
theyare[:alnum:],[:alpha:],[:cntrl:], [:digit:], [:graph:],
[:lower:],[:print:], [:punct:], [:space:], [:upper:], and [:xdigit:].
For example, [[:alnum:]] meansthecharacterclassofnumbersand
lettersin the current locale. In the C locale and ASCII character set
encoding, this is the same as .(Note that the bracketsin
theseclass names are part of the symbolic names, and must be included
in addition to the brackets delimiting the bracketexpression.) Most
meta-characterslose their special meaning inside bracket expressions.
To include a literal ] place itfirstinthelist. Similarly,to
include a literal ^ place it anywhere but first.Finally, to include a
literal - place it last.
Anchoring
The caret ^ and the dollar sign $ are meta-characters that respectively
match the empty string at the beginning and end of a line.
The Backslash Character and Special Expressions
Thesymbols\<and\>respectivelymatchthe empty string at the
beginning and end of a word.The symbol \b matches the empty string at
theedgeof a word, and \B matches the empty string provided it's not
at the edge of a word.The symbol \w is a synonym for ] and
\W is a synonym for [^_[:alnum:]].
Repetition
Aregularexpressionmaybefollowedby one of several repetition
operators:
? The preceding item is optional and 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.
{,m} The preceding item is matched at most m times.ThisisaGNU
extension.
{n,m}Theprecedingitemismatched at least n times, but not more
than m times.
Two regular expressions maybeconcatenated;theresultingregular
expressionmatchesanystring formed by concatenating two substrings
that respectively match the concatenated expressions.
Alternation
Two regular expressions may be joined bytheinfixoperator|;the
resulting regularexpressionmatchesanystringmatchingeither
alternate expression.
Precedence
Repetition takes precedence over concatenation,whichinturntakes
precedenceoveralternation. Awhole expression may be enclosed in
parenthesestooverride these precedence rules and form a
subexpression.
Back References and Subexpressions
The back-reference \n, where n is a single digit, matches the substring
previously matchedbythenthparenthesizedsubexpressionofthe
regular expression.
Basic vs Extended Regular Expressions
Inbasicregular expressions the meta-characters ?, +, {, |, (, and )
lose their special meaning; instead use thebackslashedversions\?,
\+, \{, \|, \(, and \).
ENVIRONMENT VARIABLES
The behaviorofgrepisaffectedbythefollowingenvironment
variables.
The locale for category LC_foo isspecifiedbyexaminingthethree
environmentvariablesLC_ALL, LC_foo, LANG, in that order.The first
of these variables that is set specifies the locale.Forexample,if
LC_ALLis not set, but LC_MESSAGES is set to pt_BR, then the Brazilian
Portuguese locale is used for the LC_MESSAGES category.TheClocale
isusedif none of these environment variables are set, if the locale
catalog is not installed, or if grep wasnotcompiledwithnational
language support (NLS).
GREP_OPTIONS
This variable specifies default options to be placed in front of
any explicit options.Asthiscausesproblemswhenwriting
portablescripts,thisfeaturewillberemoved in a future
Concatenation
release of grep, and grep warns if it is used. Pleaseusean
alias or script instead.
GREP_COLOR
Thisvariablespecifiesthecolorused to highlight matched
(non-empty) text.It is deprecated in favor of GREP_COLORS, but
still supported.The mt, ms, and mc capabilities of GREP_COLORS
have priority over it.It can only specify thecolorusedto
highlightthematchingnon-empty text in any matching line (a
selected line when the -v command-line option is omitted,ora
context line when -v is specified).The default is 01;31, which
means a bold redforegroundtextontheterminal'sdefault
background.
GREP_COLORS
Specifiesthecolorsandotherattributes used to highlight
various parts of the output.Itsvalueisacolon-separated
list of capabilities that defaults to
ms=01;31:mc=01;31:sl=:cx=:fn=35:ln=32:bn=32:se=36withtherv
andnebooleancapabilities omitted (i.e., false).Supported
capabilities are as follows.
sl= SGR substring for whole selectedlines(i.e.,matching
lines when the -v command-line option is omitted, or non-
matching lines when -v isspecified). Ifhoweverthe
booleanrv capability and the -v command-line option are
both specified, itappliestocontextmatchinglines
instead. Thedefaultisempty(i.e., the terminal's
default color pair).
cx= SGR substring for whole context lines (i.e., non-matching
lineswhenthe-vcommand-lineoption is omitted, or
matching lines when -v isspecified). Ifhoweverthe
booleanrv capability and the -v command-line option are
both specified, it applies to selected non-matching lines
instead. Thedefaultisempty(i.e., the terminal's
default color pair).
rv Boolean value that reverses (swaps) the meaningsofthe
sl=and cx= capabilities when the -v command-line option
is specified.The default is false (i.e., the capability
is omitted).
mt=01;31
SGR substring for matching non-empty text in any matching
line (i.e., a selectedlinewhenthe-vcommand-line
option isomitted,oracontextlinewhen-vis
specified).Setting this is equivalent tosettingboth
ms=and mc= at once to the same value.The default is a
boldredtextforeground over the current line
background.
ms=01;31
SGRsubstringfor matching non-empty text in a selected
line.(This is only used when the -v command-line option
isomitted.) Theeffectofthesl=(or cx= if rv)
capabilityremainsactivewhenthiskicksin. The
defaultisabold red text foreground over the current
line background.
mc=01;31
SGR substring for matching non-empty textinacontext
line.(This is only used when the -v command-line option
is specified.)The effect of thecx=(orsl=ifrv)
capabilityremainsactivewhenthiskicksin. The
default is a bold red text foregroundoverthecurrent
line background.
fn=35SGRsubstring for file names prefixing any content line.
Thedefaultisamagentatextforegroundoverthe
terminal's default background.
ln=32SGRsubstringforlinenumbersprefixing any content
line.The default is a green textforegroundoverthe
terminal's default background.
bn=32SGRsubstringforbyteoffsetsprefixing any content
line.The default is a green textforegroundoverthe
terminal's default background.
se=36SGRsubstringforseparators that are inserted between
selected line fields (:), betweencontextlinefields,
(-),andbetweengroups of adjacent lines when nonzero
context is specified (--).The default isacyantext
foreground over the terminal's default background.
ne Booleanvaluethat prevents clearing to the end of line
using Erase in Line (EL) to Right(\33[K)eachtimea
colorizeditemends. Thisisneeded on terminals on
which EL is not supported.Itisotherwiseusefulon
terminalsforwhichthe back_color_erase (bce) boolean
terminfo capabilitydoesnotapply,whenthechosen
highlight colors do not affect the background, or when EL
is too slow or causes too much flicker.Thedefaultis
false (i.e., the capability is omitted).
Notethatbooleancapabilitieshave no =...part.They are
omitted (i.e., false) by default and become true when specified.
SeetheSelectGraphicRendition(SGR) section in the
documentationofthetext terminal that is used for permitted
valuesandtheirmeaningascharacterattributes. These
substringvalues are integers in decimal representation and can
be concatenated with semicolons.grep takes care ofassembling
theresultintoacompleteSGR sequence (\33[...m).Common
values to concatenate include 1 for bold, 4 for underline, 5 for
blink,7 for inverse, 39 for default foreground color, 30 to 37
for foreground colors, 90 to 97for16-colormodeforeground
colors,38;5;0to38;5;255for88-color and 256-color modes
foreground colors, 49 for default background color, 40 to 47 for
backgroundcolors,100to107for16-color mode background
colors, and 48;5;0 to 48;5;255 for 88-color and 256-colormodes
background colors.
LC_ALL, LC_COLLATE, LANG
Thesevariables specify the locale for the LC_COLLATE category,
which determines the collating sequence used to interpretrange
expressions like .
LC_ALL, LC_CTYPE, LANG
Thesevariablesspecifythe locale for the LC_CTYPE category,
which determines the type of characters, e.g., whichcharacters
are whitespace.
LC_ALL, LC_MESSAGES, LANG
These variables specify the locale for the LC_MESSAGES category,
which determines the language that grep uses for messages. The
default C locale uses American English messages.
POSIXLY_CORRECT
These variables specify the locale for the LC_MESSAGES category,
which determines the language that grep uses for messages. The
default C locale uses American English messages.
POSIXLY_CORRECT
Ifset, grep behaves as POSIX requires; otherwise, grep behaves
more like other GNU programs.POSIX requires that optionsthat
followfilenamesmustbe treated as file names; by default,
such options are permuted to the front of the operandlistand
aretreated as options.Also, POSIX requires that unrecognized
options be diagnosed as “illegal”, but since they are not really
againstthelawthe default is to diagnose them as “invalid”.
POSIXLY_CORRECTalso disables _N_GNU_nonoption_argv_flags_,
described below.
_N_GNU_nonoption_argv_flags_
(HereN is grep's numeric process ID.)If the ith character of
this environment variable's value is 1, do not consider theith
operandofgrep to be an option, even if it appears to be one.
A shell can putthisvariableintheenvironmentforeach
commanditruns,specifying which operands are the results of
file name wildcard expansion and therefore should not be treated
asoptions. Thisbehaviorisavailable only with the GNU C
library, and only when POSIXLY_CORRECT is not set.
EXIT STATUS
Normally the exit status is 0 if a line is selected, 1 if no lines were
selected, and 2 if an error occurred.However, if the -q or --quiet or
--silent is used and a line is selected, the exit status is 0evenif
an error occurred.
COPYRIGHT
Copyright 1998-2000, 2002, 2005-2016 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.There is
NO warranty; not even for MERCHANTABILITY or FITNESS FORAPARTICULAR
PURPOSE.
BUGS
Reporting Bugs
Email bug reports to the bug-reporting address ⟨bug-grep@gnu.org⟩.An
email archive ⟨http://lists.gnu.org/mailman/listinfo/bug-grep⟩ and a
bug tracker ⟨http://debbugs.gnu.org/cgi/pkgreport.cgi?package=grep⟩ are
available.
Known Bugs
Large repetition counts in the {n,m} construct may causegreptouse
lots of memory.In addition, certain other obscure regular expressions
require exponential time and space, and may cause grep torunoutof
memory.
Back-references are very slow, and may require exponential time.
SEE ALSO
Regular Manual Pages
awk(1),cmp(1),diff(1),find(1), gzip(1), perl(1), sed(1), sort(1),
xargs(1), zgrep(1), read(2),pcre(3),pcresyntax(3),pcrepattern(3),
terminfo(5), glob(7), regex(7).
POSIX Programmer's Manual Page
grep(1p).
Full Documentation
A complete manual ⟨http://www.gnu.org/software/grep/manual/⟩ is
available.If the info and grep programsareproperlyinstalledat
your site, the command
info grep
should give you access to the complete manual.
NOTES
Thismanpageis maintained only fitfully; the full documentation is
often more up-to-date.
User Commands GNU grep 2.25 GREP(1)
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