一，grep命令有什么用
个人觉得Linux下grep命令就是一个对文本或输出进行匹配并控制输出的一个工具,看一下下面的参数，部分翻译了，有不对的地方，还请指正
grep –help匹配模式选择:-E, –extended-regexp 扩展正则表达式egrep-F, –fixed-strings 一个换行符分隔的字符串的集合fgrep-G, –basic-regexp 基本正则-P, –perl-regexp 调用的perl正则-e, –regexp=PATTERN 后面根正则模式，默认无-f, –file=FILE 从文件中获得匹配模式-i, –ignore-case 不区分大小写-w, –word-regexp 匹配整个单词-x, –line-regexp 匹配整行-z, –null-data a data line ends in 0 byte, not newline
杂项:-s, –no-messages 不显示错误信息-v, –invert-match 显示不匹配的行-V, –version 显示版本号–help 显示帮助信息–mmap use memory-mapped input if possible
输入控制:-m, –max-count=NUM 匹配的最大数-b, –byte-offset 打印匹配行前面打印该行所在的块号码。-n, –line-number 显示的加上匹配所在的行号–line-buffered 刷新输出每一行-H, –with-filename 当搜索多个文件时，显示匹配文件名前缀-h, –no-filename 当搜索多个文件时，不显示匹配文件名前缀–label=LABEL print LABEL as filename for standard input-o, –only-matching show only the part of a line matching PATTERN-q, –quiet, –silent 不显示任何东西–binary-files=TYPE assume that binary files are TYPETYPE is ‘binary’, ‘text’, or ‘without-match’-a, –text 匹配二进制的东西-I 不匹配二进制的东西-d, –directories=ACTION 目录操作，读取，递归，跳过ACTION is ‘read’, ‘recurse’, or ‘skip’-D, –devices=ACTION 设置对设备，，FIFO,管道的操作，读取，跳过ACTION is ‘read’ or ‘skip’-R, -r, –recursive 递归调用–include=PATTERN files that match PATTERN will be examined–exclude=PATTERN files that match PATTERN will be skipped.–exclude-from=FILE files that match PATTERN in FILE will be skipped.-L, –files-without-match 匹配多个文件时，显示不匹配的文件名-l, –files-with-matches 匹配多个文件时，显示匹配的文件名-c, –count 显示匹配了多少次-Z, –null print 0 byte after FILE name
文件控制:-B, –before-context=NUM 打印匹配本身以及前面的几个行由NUM控制-A, –after-context=NUM 打印匹配本身以及随后的几个行由NUM控制-C, –context=NUM 打印匹配本身以及随后，前面的几个行由NUM控制-NUM 根-C的用法一样的–color[=WHEN],–colour[=WHEN] use markers to distinguish the matching stringWHEN may be `always’, `never’ or `auto’.-U, –binary do not strip CR characters at EOL (MSDOS)-u, –unix-byte-offsets report offsets as if CRs were not there (MSDOS)
一个人去旅行，而且是去故乡的山水间徜徉。
