grep 搜索文本文件中与指定正则表达式匹配的行
命令格式
grep [OPTIONS] PATTERN [FILE...]
命令参数
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
实例
测试文件 test.txt：
The Zen of Python, by Tim Peters Beautiful is better than ugly Explicit is better than implicit Simple is better than complex Complex is better than complicated Flat is better than nested Sparse is better than dense Readability counts Special cases aren‘t special enough to break the rules Although practicality beats purity Errors should never pass silently Unless explicitly silenced In the face of ambiguity, refuse the temptation to guess There should be one-- and preferably only one --obvious way to do it Although that way may not be obvious at first unless you‘re Dutch Now is better than never Although never is often better than *right* now If the implementation is hard to explain, it‘s a bad idea If the implementation is easy to explain, it may be a good idea Namespaces are one honking great idea -- let‘s do more of those
a) 输出含有 "com" 的行
[email protected]:~/huey/linux/cmdline$ grep com test.txt Simple is better than complex Complex is better than complicated
b) 匹配时忽略大小写
[email protected]:~/huey/linux/cmdline$ grep -i com test.txt Simple is better than complex Complex is better than complicated
c) 输出以 "complex" 开头的行，忽略大小写
[email protected]:~/huey/linux/cmdline$ grep -i ‘^complex‘ test.txt Complex is better than complicated
d) 输出以 “idea” 结尾的行
[email protected]:~/huey/linux/cmdline$ grep ‘idea$‘ test.txt If the implementation is hard to explain, it‘s a bad idea If the implementation is easy to explain, it may be a good idea
e) 匹配空行
[email protected]:~/huey/linux/cmdline$ grep -n ‘^$‘ test.txt 2:
h) 输出含有 "good" 或 "bad" 的行
[email protected]:~/huey/linux/cmdline$ grep ‘good\|bad‘ test.txt If the implementation is hard to explain, it‘s a bad idea If the implementation is easy to explain, it may be a good idea [email protected]:~/huey/linux/cmdline$ grep -E ‘good|bad‘ test.txt If the implementation is hard to explain, it‘s a bad idea If the implementation is easy to explain, it may be a good idea
i) 精确匹配单词 it，像 implicit、purity、purity 等这样的单词是不会被匹配的
[email protected]:~/huey/linux/cmdline$ grep -w it test.txt There should be one-- and preferably only one --obvious way to do it If the implementation is hard to explain, it‘s a bad idea If 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
[email protected]:~/huey/linux/cmdline$ grep -A 3 Python test.txt The Zen of Python, by Tim Peters Beautiful is better than ugly Explicit is better than implicit
相关命令
egrep - 相当于 grep -E
fgrep - 相当于 grep -F
pgrep - 相当于 grep -P