shell 学习之脚本编写1

脚本要求：

执行脚本后

　　接受输入1，显示当前时间，并提示是否继续选择。

　　 接受输入2，显示CPU负载，并提示是否继续选择。

　　 接受输入3，显示剩余内存，并提示是否继续选择。

　　 接受输入0，退出脚本。

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思路:

　　显示当前时间

[root@wk ~]# date +%T
08:26:04

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uptime命令能显示1）当前系统时间；

　　　　　　　　2）本机已经运行时间；

　　　　　　　　3）当前系统有几个用户连接；

　　　　　　　　4）本机最近1分钟、5分钟、15分钟系统的平均负载。

如下：

我们可以将uptime的输出结果用awk来进行选择输出。

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free -m 命令能以M为单位显示内存使用情况，还有交换分区swap的使用情况 ，可用awk打印出Mem行第4列的信息，即是我们要的信息。

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至于提示是否继续选择，可以用while循环。最终脚本如下：

 #!/bin/bash
 #
 while [ "" == "" ]
 do
     clear
     echo "~~~~~~~~~~~~~~~~~~~menu~~~~~~~~~~~~~~~~~~~~~~"
     echo "              1) Time Now                    "
     echo "              2) CPU Load                    "
     echo "              3) Memory Free                 "
     echo "              0) Exit                        "
     echo "~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~"
     echo "Please enter a chose[0~3]:"
     read NUM
     case ${NUM} in
       ) echo "Time Now :`date +%T`" ;;
       ) echo "CPU Load :`uptime |awk -F'[:,]' '{print $6}'`" ;;
       ) echo "Memory Free :`free -m |awk '$1=="Mem:" {print $4}'`m" ;;
       ) exit ;;
       *) echo "This chose is not in [0~3]."
     esac
     echo -n "Do you continue [y/n]:"
     read continue
     if [ "${contiune}" == "n" -o "${continue}" == "N" ]
     then
            exit
     fi
 done