Shell–grep Common usage

is a powerful text search tool that can use regular expressions to search for text and print matching lines.
I often use it to find strings such as:

    grep -rn "字符串" .

Recursively finds the "string" in all files in the current directory and the line in which it is marked.

Here's a look at the specific parameters:

    grep [-acinv] [--color=auto] ‘搜寻字符串‘ filename 选项参数:    -a :将 binary 档案以 text 档案方式搜寻数据    -c :计算找刡 ‘搜寻字符串‘ 次数    -i :忽略大小写    -n :输出行号    -v :反向选择，亦即显示出没有 ‘搜寻字符串‘ 内容癿那一行! --color=auto :可以将找刡癿关键词部分加上颜色癿显示!    -A :后面可加数字，为 after 癿意思，除了列出该行外，后续的 n 行也列出;     -B :后面可加数字，为 befer 癿意思，除了列出该行外，前面的 n 行也列出;

GREP supports only the underlying regular notation, and if you want to extend the regular, use Egrep or GREP-E.

The basic regular notation is summarized as follows:

    ^word：查找字符串(word)在行首  grep -n ‘^word‘ filename    word$:  查找字符串(word)在行末  grep -n ‘word$‘ filename    . : 任意字符    \ : 转译    *：前面字符 0 到 任意多个    [] : 字符集合    [n1-n2] : 范围  如[0-9]    [^]: 字符取反，就是不能是里面的字符    \{n,m\}: 出现n到m次

The extension of the regular presentation is summarized as follows:

    +  ：一个或者一个以上    ？ ：零个或者一个    |   ： 或    ()  :  群组   egrep -n ‘g(la|oo)d‘ filename  找出 glad 或者 good 两个字符串    ()+:  群组出现一次或者多次

grep also has a lot of advanced usage, please be interested in the replenishment, I only listed the basic common usage.

Shell–grep Common usage