Linux常用基本命令:grep-从文件或者管道中筛选匹配的行

grep命令

作用：从文本文件或管道数据流中筛选匹配的行及数据，配合正则表达式一起使用，功能更加强大。

格式:

grep [options] [pattern] [file]

１，匹配包含"ghostwu"的行

ghostwu@dev:~/linux/grep$ cat -n ghostwu.txt
         my name is ghostwu
         how are you
         fine think you
         My name is Ghostwu
         what's your name?
         my name is ghostwu2

ghostwu@dev:~/linux/grep$ grep "ghostwu" ghostwu.txt
my name is ghostwu
my name is ghostwu2

２，-v: 不包含，相当于取反

ghostwu@dev:~/linux/grep$ grep -v "ghostwu" ghostwu.txt
how are you
fine think you
My name is Ghostwu
what's your name?

ghostwu@dev:~/linux/grep$ 

３，-n　添加行号

ghostwu@dev:~/linux/grep$ grep -n "ghostwu" ghostwu.txt
:my name is ghostwu
:my name is ghostwu2
ghostwu@dev:~/linux/grep$ grep -vn "ghostwu" ghostwu.txt
:how are you
:fine think you
:My name is Ghostwu
:what's your name?
:

４，-E，使用扩展的egrep命令，模式中可以用正则表达式

ghostwu@dev:~/linux/grep$ cat ghostwu.txt
my name is ghostwu
how are you
fine think you
My name is Ghostwu
what's your name?
my name is ghostwu2

ghostwu@dev:~/linux/grep$ grep -E "my|your" ghostwu.txt
my name is ghostwu
what's your name?
my name is ghostwu2
ghostwu@dev:~/linux/grep$ grep -Ev "my|your" ghostwu.txt
how are you
fine think you
My name is Ghostwu

ghostwu@dev:~/linux/grep$ grep -En "my|your" ghostwu.txt
:my name is ghostwu
:what's your name?
:my name is ghostwu2

５，-i选项，不区分大小写

ghostwu@dev:~/linux/grep$ grep "ghostwu" ghostwu.txt
my name is ghostwu
my name is ghostwu2
ghostwu@dev:~/linux/grep$ grep -i "ghostwu" ghostwu.txt
my name is ghostwu
My name is Ghostwu
my name is ghostwu2

６，-c :统计匹配的行数，不是匹配字符串的次数

ghostwu@dev:~/linux/grep$ grep -c "ghostwu" ghostwu.txt 

ghostwu@dev:~/linux/grep$ grep -ci "ghostwu" ghostwu.txt

ghostwu@dev:~/linux/grep$ grep -c "ghostwu" ghostwu.txt 

ghostwu@dev:~/linux/grep$ grep "ghostwu" ghostwu.txt
my name is ghostwu, nice to meet you,ghostwu
my name is ghostwu2
ghostwu@dev:~/linux/grep$ cat -n ghostwu.txt
         my name is ghostwu, nice to meet you,ghostwu
         how are you
         fine think you
         My name is Ghostwu
         what's your name?
         my name is ghostwu2
         

７，-o: 只输出匹配到的字符串

ghostwu@dev:~/linux/grep$ grep -o "ghostwu" ghostwu.txt
ghostwu
ghostwu
ghostwu@dev:~/linux/grep$ grep -oi "ghostwu" ghostwu.txt
ghostwu
Ghostwu
ghostwu

８，-w: 只匹配过滤的单词，类似于精确匹配

ghostwu@dev:~/linux/grep$ grep -w "ghostwu" ghostwu.txt
my name is ghostwu, nice to meet you,ghostwu
ghostwu@dev:~/linux/grep$ grep -wi "ghostwu" ghostwu.txt
my name is ghostwu, nice to meet you,ghostwu
My name is Ghostwu
ghostwu@dev:~/linux/grep$ cat -n ghostwu.txt
         my name is ghostwu, nice to meet you,ghostwu
         how are you
         fine think you
         My name is Ghostwu
         what's your name?
         my name is ghostwu2
         

９，常用的一招小技巧，去除文件的注释和空行，在运维中，可以用这条命令把配置文件的空行和注释去掉，然后用管道生成。这样配置文件比较容易查看和配置

ghostwu@dev:~/linux/grep$ grep -Ev "^$|#" ghostwu.php
<?php
    class Person {
        public $name = 'ghostwu';
        public $age = ;
        public function showinfo(){
            echo $this->name . PHP_EOL;
            echo $this->age. PHP_EOL;
        }
    }
ghostwu@dev:~/linux/grep$ cat -n ghostwu.php
         <?php

             class Person {

                 #人名
                 public $name = 'ghostwu';

                 #年龄
                 public $age = ;

                #显示信息　
                public function showinfo(){
                    echo $this->name . PHP_EOL;
                    echo $this->age. PHP_EOL;
                }
            }