grep

grep--搜素匹配的字符，正則表達式

grep [options] pattern [FILE...]
grep [options] [-e pattern | -f FILE]  [FILE...]

描述
grep searches the named input FILEs for lines containing a match to the given PATTERN. By default, grep prints the matching lines.
Linux系統中grep命令是一種強大的文本搜索工具，它能使用正則表達式搜索文本，並把匹 配的行打印出來。grep全稱是Global Regular Expression Print，表示全局正則表達式版本，它的使用權限是全部用戶。

options
-E, --extended-regexp     使用擴展正則表達式Interpret PATTERN as an extended regular expression.
-F, --fixed-strings     Interpret PATTERN as a list of fixed strings,separated by newlines, any of which is to be matched.
-G, --basic-regexp     Interpret PATTERN as a basic regular expression. This is the default.
-P, --perl-regexp    Interpret  PATTERN  as  a  Perl  regular  expression (PCRE, see below).  This is highly experimental and grep -P may warn of unimplemented features.

-v, --invert-match 不匹配的行。Invert the sense of matching, to select non-matching lines.  (-v is specified by POSIX.)

-w, --word-regexp 打印匹配整個單詞的整行。Select  only  those lines containing matches that form whole words.  The test is that the matching substring must either be at the  beginning  of  the  line,  or preceded  by  a non-word constituent character.  Similarly, it must be either at the end of the line or followed by  a  non-word  constituent  character.   Word-constituent characters are letters, digits, and the underscore.

-x, --line-regexp 打印匹配的整行。Select  only  those matches that exactly match the whole line.  (-x is specified by POSIX.)

-c, --count      打印每一個文件匹配的總行數。Suppress normal output; instead print a count of matching lines for  each  input file.  With the -v, --invert-match option (see below), count non-matching lines.(-c is specified by POSIX.)

-L, --files-without-match     列出不匹配的文件名。Suppress  normal output; instead print the name of each input file from which no output would normally have been printed.  The scanning will stop on the first match.

-l, --files-with-matches    列出匹配的文件名。Suppress normal output; instead print the name of each input  file  from  which  output would  normally  have been printed.  The scanning will stop on the first match.  (-l is specified by POSIX.)

-n, --line-number     行前打印行號。Prefix each line of output with the 1-based line number within its input file.  (-n  is specified by POSIX.)

-i    不區分大小寫（只適合單字符）
-h    查詢多文件時不顯示文件名。