2019-03-10

shell中的case判断

格式

在case程序中，能够在条件中使用|，表示或的意思， 好比2|3表示valuel能够是2也能够是3

案例：

#!/bin/bash

read -p "Please input a number: " n #输入一个数字赋值给n。

if [ -z "$n" ]                                        #若是变量n为空

then

        echo "Please input a number." #显示“请输入一个数字”

        exit 1                                         #退出脚本

fi

n1=`echo $n|sed 's/[0-9]//g'`            #给n1赋值“删除变量n中所有数字

if [ -n "$n1" ]                                     #若是变量n1不为空（就是包含数字之外的东西）

then                                                   #就

    echo "Please input a number."     #显示“请输入一个数字”

    exit 1                                             #退出脚本

fi

if [ $n -lt 60 ] && [ $n -ge 0 ]             #若是变量n小于60且大于等于0

then                                                    #就

        tag=1                                         #给变量tag赋值为1

elif [ $n -ge 60 ] && [ $n -lt 80 ]        #不然判断是否大于等于60且小于80

then                                                     #若是是

        tag=2                                           #给变量tag赋值为2

elif [ $n -ge 80 ] && [ $n -lt 90 ]         #不然判断是否大于等于80且小于90

then                                                     #若是是

         tag=3                                          #给变量tag赋值为3

elif [ $n -ge 90 ] && [ $n -le 100 ]      #不然判断是否大于等于90且小于等于100

 then                                                     #若是是

          tag=4                                         #给变量tag赋值为4

else                                                       #不然

          tag=0                                         #给变量tag赋值为0

fi

case $tag in

        1)                                     #变量tag的值为1

            echo "not ok" #显示not ok ;;

        2)                                     #变量tag的值为2

            echo "ok"                     #显示ok ;;

        3) echo "ook"

             ;;     

        4) echo "oook"

             ;;

          *)                                      #除了以上状况外

             echo "The number range is 0-100." #显示数字的范围是0-100

             ;;

       esac

shell中的for循环

语法: for 变量名 in 条件; do （命令）; done #知足in后的条件退出，不然重复执行do后的命令。

 

#!/bin/bash

sum=0

for i in `seq 1 100`   #记数命令：seq 起点 步长 终点（从起点数到终点，按步长记数。默认为1） do             sum=$[$sum+$i] #为sum赋值从0累加1至100

            echo $i #显示变量i的值

done

echo $sum

文件列表循环

#!/bin/bash

cd /etc/

for a in `ls /etc/`

do

        if [ -d $a ]

        then

                ls -d $a

        fi

done

shell中的while循环

语法 while 条件; do … ; done 案例1

#!/bin/bash while : do load=w|head -1|awk -F 'load average: ' '{print $2}'|cut -d. -f1 if [ $load -gt 10 ] then top|mail -s "load is high: $load" asldkfls@11.com fi sleep 30 done

案例2 #!/bin/bash while : do read -p "Please input a number: " n if [ -z "$n" ] then echo "you need input sth." continue fi n1=echo $n|sed 's/[0-9]//g' if [ -n "$n1" ] then echo "you just only input numbers." continue fi break done echo $n