学习笔记-第07天-命令合集6

重定向

       1. 标准输出重定向，用数字1表示

       2. 标准错误输出重定向，用数字2表示

       3. 标准输入重定向，用数字0来表示。

1)标准[输出]重定向:

>或1>，数据流向就是朝右.

[root@localhost ~]# echo oldboy
oldboy
[root@localhost ~]# echo oldboy >oldboy.txt
[root@localhost ~]# cat oldboy.txt
oldboy
[root@localhost ~]# echo oldboy 1>oldboy.txt
[root@localhost ~]# cat oldboy.txt
oldboy

1.输出oldboy。

2.清空oldboy.txt

3.把oldboy写入到oldboy.txt

常用清空文件命令:

[root@localhost ~]# >oldboy.txt
[root@localhost ~]# cat oldboy.txt
[root@localhost ~]# cat /dev/null>oldboy.txt

2) 标准[错误输出]重定向：

2>接收执行命令的报错

       作用：接收执行命令的报错。

[root@localhost ~]# cat oldboy.txt
[root@localhost ~]# ls >oldboy.txt
[root@localhost ~]# cat oldboy.txt
oldboy.txt
[root@localhost ~]# ls
oldboy.txt
[root@localhost ~]# ls >oldboy.txt
[root@localhost ~]# ls 2>oldboy.txt
oldboy.txt
[root@localhost ~]# cat oldboy.txt
[root@localhost ~]# 2>oldboy.txt
[root@localhost ~]# cat oldboy.txt
[root@localhost ~]# lss
-bash: lss: command not found
[root@localhost ~]# cat oldboy.txt
[root@localhost ~]# lss 2>oldboy.txt
[root@localhost ~]# cat oldboy.txt
-bash: lss: command not found
[root@localhost ~]# ls >oldboy.txt 2>oldgirl.txt
[root@localhost ~]# cat oldboy.txt
oldboy.txt
oldgirl.txt
[root@localhost ~]# cat oldgirl.txt
[root@localhost ~]# lss >oldboy.txt 2>oldgirl.txt
[root@localhost ~]# >oldboy.txt
[root@localhost ~]# cat oldboy.txt
[root@localhost ~]# cat oldgirl.txt
-bash: lss: command not found

3) 标准[输入]重定向，0来表示:

     0<或< 数据流向朝左。

     tr 按字符替换：

[root@localhost ~]# cat oldboy.txt
oldboy
oldboy.txt
oldgirl.txt
[root@localhost ~]# tr "old" "abc"<oldboy.txt
abcbay
abcbay.txt
abcgirb.txt
[root@localhost ~]# tr "a-g" "1-7"<oldboy.txt
ol42oy
ol42oy.txt
ol47irl.txt

Xargs (从标准输入接收数据)

-n  分组：

4) 标准【追加】输出重定向：

    >>或1>>，数据流向就是朝右，标准【追加】输出重定向：

[root@localhost ~]# echo oldboy >>oldboy.txt
[root@localhost ~]# cat oldboy.txt
oldboy
oldboy.txt
oldgirl.txt
Oldboy

解释:

1. 输出oldboy；

2. 把oldboy追加到oldboy.txt结尾。

5) 标准错误【追加】输出重定向：

     >>或2>>，数据流向就是超右，标准【追加】输出重定向：

[root@localhost ~]# lss
-bash: lss: command not found
[root@localhost ~]# lss 2>a.txt
[root@localhost ~]# cat a.txt
-bash: lss: command not found
[root@localhost ~]# dfff 2>a.txt
[root@localhost ~]# cat a.txt
-bash: dfff: command not found
[root@localhost ~]# lss 2>>a.txt
[root@localhost ~]# cat a.txt
-bash: dfff: command not found
-bash: lss: command not found
[root@localhost ~]# dfff 2>>a.txt
[root@localhost ~]# cat a.txt
-bash: dfff: command not found
-bash: lss: command not found
-bash: dfff: command not found

6) 标准输入【追加】重定向，0来表示

    0<<或<< 数据流向朝左

（大段内容非交互式编辑）

[root@localhost ~]# cat  <<eof
>      ddd
> fff
> eof
     ddd
fff
[root@localhost ~]# cat  >a.txt  <<eof
> ddd
> fff
> eof
[root@localhost ~]# cat a.txt
ddd
fff

特殊情况：希望用一个文件同时接受手机错误和正确的信息。

方法一：

echo oldboy >>oldboy.txt 2>>oldboy.txt

[root@localhost ~]# echo oldboy >>oldboy.txt 2>>oldboy.txt
[root@localhost ~]# cat oldboy.txt
oldboy
oldboy.txt
oldgirl.txt
oldboy
oldboy
[root@localhost ~]# cho oldboy >>oldboy.txt 2>>oldboy.txt
[root@localhost ~]# cat oldboy.txt
oldboy
oldboy.txt
oldgirl.txt
oldboy
oldboy
-bash: cho: command not found

方法二：

        cho oldboy &>>oldboy.txt

[root@localhost ~]# cho oldboy &>>oldboy.txt
[root@localhost ~]# cat oldboy.txt
oldboy
oldboy.txt
oldgirl.txt
oldboy
oldboy
-bash: cho: command not found
-bash: cho: command not found

方法三：

      cho oldboy 1>>oldboy.txt 2>&1

[root@localhost ~]# cho oldboy 1>>oldboy.txt 2>&1
[root@localhost ~]# cat oldboy.txt
oldboy
oldboy.txt
oldgirl.txt
oldboy
oldboy
-bash: cho: command not found
-bash: cho: command not found
-bash: cho: command not found

别名永久生效：

全局环境变量文件：

/etc/profile

/etc/bashrc

用户环境变量文件：

~/.bash_profile

~/.bashrc

[root@localhost ~]# vim /etc/profile

按键盘大写GG到命令行最后一行，按o进行编辑自己所写的变量内容，按键盘esc，wq!进行保存强制退出。

[root@localhost ~]# a=2
[root@localhost ~]# echo $a
2

uniq  去重：

-c 计数

[root@localhost ~]# cat  >test.txt  <<EOF
10.0.0.1
10.0.0.11
10.0.0.1
10.0.0.1
10.0.0.2
10.0.0.8
10.0.0.8
10.0.0.16
EOF
[root@localhost ~]# uniq test.txt  #相邻的相同行去重
10.0.0.1
10.0.0.11
10.0.0.1
10.0.0.2
10.0.0.8
10.0.0.16

-c 计数：

[root@localhost ~]# uniq -c test.txt  #相邻的相同行去重并且计数。
      1 10.0.0.1
      1 10.0.0.11
      2 10.0.0.1
      1 10.0.0.2
      2 10.0.0.8
      1 10.0.0.16

sort 排序：

[root@localhost ~]# sort test.txt
10.0.0.1
10.0.0.1
10.0.0.1
10.0.0.1
10.0.0.1
10.0.0.1
10.0.0.11
10.0.0.16
10.0.0.18
10.0.0.2
10.0.0.8
10.0.0.8
10.0.0.8
10.0.0.8
10.0.0.8
[root@localhost ~]# sort test.txt >u.txt   #按数字顺序排序
[root@localhost ~]# uniq -c u.txt        #整个文件实现了去重并且计数
      6 10.0.0.1
      1 10.0.0.11
      1 10.0.0.16
      1 10.0.0.18
      1 10.0.0.2
      5 10.0.0.8

-n  按数字排序

-t  指定分隔符

-k  指定列

[root@localhost ~]# sort -n test.txt
10.0.0.1
10.0.0.1
10.0.0.1
10.0.0.1
10.0.0.1
10.0.0.1
10.0.0.11
10.0.0.16
10.0.0.18
10.0.0.2
10.0.0.8
10.0.0.8
10.0.0.8
10.0.0.8
10.0.0.8
[root@localhost ~]# sort -n -t. -k4 test.txt
10.0.0.1
10.0.0.1
10.0.0.1
10.0.0.1
10.0.0.1
10.0.0.1
10.0.0.2
10.0.0.8
10.0.0.8
10.0.0.8
10.0.0.8
10.0.0.8
10.0.0.11
10.0.0.16
10.0.0.18

-r  指倒序排序

[root@localhost ~]# sort -rn -t. -k4 test.txt
10.0.0.18
10.0.0.16
10.0.0.11
10.0.0.8
10.0.0.8
10.0.0.8
10.0.0.8
10.0.0.8
10.0.0.2
10.0.0.1
10.0.0.1
10.0.0.1
10.0.0.1
10.0.0.1
10.0.0.1
[root@localhost ~]# sort -rn -t. -k4 test.txt >ab.txt
[root@localhost ~]# uniq -c ab.txt
      1 10.0.0.18
      1 10.0.0.16
      1 10.0.0.11
      5 10.0.0.8
      1 10.0.0.2
      6 10.0.0.1
[root@localhost ~]# uniq -c ab.txt >b.txt
[root@localhost ~]# sort -rn b.txt
      6 10.0.0.1
      5 10.0.0.8
      1 10.0.0.2
      1 10.0.0.18
      1 10.0.0.16
      1 10.0.0.11

|管道：

[root@localhost ~]# cat oldboy.txt |grep oldboy
oldboy
oldboy.txt
oldboy
oldboy

用管道处理上序IP排序问题：

[root@localhost ~]# sort test.txt|uniq -c|sort -rn
      6 10.0.0.1
      5 10.0.0.8
      1 10.0.0.2
      1 10.0.0.18
      1 10.0.0.16
      1 10.0.0.11
[root@localhost ~]# sort test.txt|uniq -c|sort -rn -t. -k4
      1 10.0.0.18
      1 10.0.0.16
      1 10.0.0.11
      5 10.0.0.8
      1 10.0.0.2
      6 10.0.0.1