Linux Shell脚本学习笔记

淡淡的烟草味﹌ 2022-05-29 10:27 224阅读 0赞

### 一、第一个Shell脚本（[hello-01.sh][]） ###

#!/bin/bash
    echo "Hello World!"
    echo "Hello Shell!"

shell脚本执行

chmod 755 hello-01.sh 
    sh hello-01.sh 
    ./hello-01.sh

### 二、第二个Shell脚本 ###

下面的脚本使用 read 命令从 stdin 获取输入并赋值给 name变量，最后在 stdout 上输出

[root@localhost testshell]# ll
    total 8
    -rwxr-xr-x. 1 root root 52 Mar 21 18:32 hello-01.sh
    -rw-r--r--. 1 root root 68 Mar 21 18:44 hello-02.sh
    [root@localhost testshell]# chmod 755 hello-02.sh 
    [root@localhost testshell]# sh hello-02.sh 
    What is your name?
    Tian Ming
    Hello Tian Ming!
    [root@localhost testshell]# cat hello-02.sh 
    #!/bin/bash
    echo "What is your name?"
    read name
    echo "Hello $name!"

### 三、shell变量的定义（[hello-03.sh][]） ###

> **shell变量的定义时，等号（=）两边不能有空格**

[root@localhost testshell]# chmod 755 hello-03.sh 
    [root@localhost testshell]# cat hello-03.sh 
    #!/bin/bash
    TVDrama="game of thrones"
    echo $TVDrama
    
    myUrl="http://see.xidian.edu.cn/cpp/u/xitong/"
    echo $myUrl
    unset myUrl
    echo $myUrl
    [root@localhost testshell]# sh hello-03.sh 
    game of thrones
    http://see.xidian.edu.cn/cpp/u/xitong/

### 四、Shell特殊变量 ###

[root@localhost testshell]# chmod 755 hello-04.sh 
    [root@localhost testshell]# cat -n hello-04.sh 
         1  #!/bin/bash
         2  # $ representing the ID of the current Shell process, that is, PID
         3  echo $$
         4  echo "File Name: $0"
         5  echo "First Parameter : $1"
         6  echo "First Parameter : $2"
         7  echo "Quoted Values: $@"
         8  echo "Quoted Values: $*"
         9  echo "Total Number of Parameters : $#"
        10
    [root@localhost testshell]# sh hello-04.sh 
    4704
    File Name: hello-04.sh
    First Parameter : 
    First Parameter : 
    Quoted Values: 
    Quoted Values: 
    Total Number of Parameters : 0

### 五、Shell替换 ###

>  *  **这里 -e 表示对转义字符进行替换。如果不使用 -e 选项，将会原样输出**
>  *  **命令替换的语法： `command` 【注意是反引号，不是单引号，这个键位于 Esc 键下方。】**

[root@localhost testshell]# chmod 777 hello-05.sh 
    [root@localhost testshell]# cat hello-05.sh 
    #!/bin/bash
    sky=10
    echo -e "Value of sky is $sky \n"
    
    DATE=`date`
    echo -e "Date is $DATE"
    
    USERS=`who | wc -l`
    echo -e "Logged in user are $USERS"
    
    UP=`date ; uptime`
    echo -e "Uptime is $UP"
    [root@localhost testshell]# sh hello-05.sh 
    Value of sky  is 10  
    
    Date is Fri Mar 30 01:42:08 PDT 2018
    Logged in user are 5
    Uptime is Fri Mar 30 01:42:08 PDT 2018
     01:42:08 up  2:10,  5 users,  load average: 0.04, 0.04, 0.05
    [root@localhost testshell]#

--------------------

参考文档：

1.  [http://c.biancheng.net/cpp/view/2739.html][http_c.biancheng.net_cpp_view_2739.html]

[hello-01.sh]: http://hello-01.sh
[hello-03.sh]: http://hello-03.sh
[http_c.biancheng.net_cpp_view_2739.html]: http://c.biancheng.net/cpp/view/2739.html