Linux 命令

grep 搜索文本文件中与指定正则表达式匹配的行

grep [OPTIONS] PATTERN [FILE...]

Generic PRogram Information

--help　　打印帮助信息

-V, --version　　打印版本信息

Matcher Selection

-E, --extended-regexp　　使用基本正则表达式（ERE）解释 PATTERN

-F, --fixed-strings　　每个模式作为一组固定字符串对待（以新行分隔），而不作为正则表达式。

-G, --basic-regexp　　使用基本正则表达式（BRE）解释 PATTERN

-P, --perl-regexp　　使用 Perl 正则表达式（PCRE）解释 PATTERN

Matching Control

-e PATTERN, --regexp=PATTERN　　使用 PATTERN 作为匹配模式

-f FILE, --file=FILE　　从文件获取匹配模式

-i, --ignore-case　　忽略大小写

-v, --invert-match　　输出不含匹配项的行

-w, --Word-regexp　　单词精确匹配

-x, --line-regexp　　行精确匹配

General Output Control

-c, --count　　输出匹配项的数目

-l, --files-with-matches　　输出包含匹配项的文件名而不是直接输出匹配行

-L, --files-without-match　　与 -l 选项类似，输出的是包含不匹配项的文件名

-m NUM, --max-count=NUM　　当匹配 NUM 后停止读取文件

-o, --only-matching　　只显示匹配项而不是匹配行

-q, --quiet, --silent　　安静模式，不显示任何信息

-s, --no-messages　　当文件不存在或不可读时，不显示错误信息

Output Line Prefix Control

-b, --byte-offset　　在每个匹配行前加上该行在文件内的块号

-H, --with-filename　　在每个匹配行前加上文件名

-h, --no-filename　　多文件搜索时，抑制文件名输出

-n, --line-number　　在每个匹配行前加上该行在文件内的行号

Context Line Control

-A NUM, --after-context=NUM　　输出匹配行及其后 NUM 行的内容

-B NUM, --before-context=NUM　　输出匹配行及其前 NUM 行的内容

-C NUM, -NUM, --context=NUM　　输出匹配行及其前后 NUM 行的内容

测试文件 test.txt：

The Zen of Python, by Tim PetersBeautiful is better than uglyExplicit is better than implicitSimple is better than complexComplex is better than complicatedFlat is better than nestedSparse is better than denseReadability countsSpecial cases aren't special enough to break the rulesAlthough practicality beats purityErrors should never pass silentlyUnless explicitly silencedIn the face of ambiguity, refuse the temptation to guessThere should be one-- and preferably only one --obvious way to do itAlthough that way may not be obvious at first unless you're DutchNow is better than neverAlthough never is often better than *right* nowIf the implementation is hard to explain, it's a bad ideaIf the implementation is easy to explain, it may be a good ideaNamespaces are one honking great idea -- let's do more of those

a) 输出含有 "com" 的行

huey@huey-K42JE:~/huey/linux/cmdline$ grep com test.txtSimple is better than complexComplex is better than complicated

b) 匹配时忽略大小写

huey@huey-K42JE:~/huey/linux/cmdline$ grep -i com test.txtSimple is better than complexComplex is better than complicated

c) 输出以 "complex" 开头的行，忽略大小写

huey@huey-K42JE:~/huey/linux/cmdline$ grep -i '^complex' test.txtComplex is better than complicated

d) 输出以 "idea" 结尾的行

huey@huey-K42JE:~/huey/linux/cmdline$ grep 'idea$' test.txtIf the implementation is hard to explain, it's a bad ideaIf the implementation is easy to explain, it may be a good idea

e) 匹配空行

huey@huey-K42JE:~/huey/linux/cmdline$ grep -n '^$' test.txt2:

h) 输出含有 "good" 或 "bad" 的行

huey@huey-K42JE:~/huey/linux/cmdline$ grep 'good/|bad' test.txtIf the implementation is hard to explain, it's a bad ideaIf the implementation is easy to explain, it may be a good ideahuey@huey-K42JE:~/huey/linux/cmdline$ grep -E 'good|bad' test.txtIf the implementation is hard to explain, it's a bad ideaIf the implementation is easy to explain, it may be a good idea

i) 精确匹配单词 it，像 implicit、purity、purity 等这样的单词中的 it 部分是不会被匹配的

huey@huey-K42JE:~/huey/linux/cmdline$ grep -w it test.txtThere should be one-- and preferably only one --obvious way to do itIf the implementation is hard to explain, it's a bad ideaIf the implementation is easy to explain, it may be a good idea

j) 输出含有 "Python" 的行及其后 3 行

huey@huey-K42JE:~/huey/linux/cmdline$ grep -A 3 Python test.txtThe Zen of Python, by Tim PetersBeautiful is better than uglyExplicit is better than implicit

egrep - 相当于 grep -E

fgrep - 相当于 grep -F

pgrep - 相当于 grep -P