linux 学习随笔-shell简单编写,随笔-shell
linux 学习随笔-shell简单编写,随笔-shell
脚本最好都放在/usr/local/sbin中
脚本的执行 sh -x 脚本.sh -x可以查看执行过程 1在脚本中使用变量 使用变量的时候,需要使用$符号: #!/bin/bash ##把命令赋值为变量,需要使用反引号 d=`date +"%H:%M:%S"` echo "The script begin at $d" echo "Now we'll sleep 2 seconds" sleep 2 d1=`date +"%H:%M:%S"` echo "The script end at $d" 2在脚本中使用数学运算要用[]括起来如下 #! /bin/bash a=1 b=2 ##数学运算用[]括起来 sum=$[$a+$b] echo "$a + $b = $sum" 3在脚本中和控制台交互 使用read命令 #! /bin/bash read -p "Please input a number: " x read -p "Please input a number: " y sum=$[$x+$y] echo "The sum of the tow numbers is : $sum" 4shell中的预设变量 #! /bin/bash echo "$1 $2 $3 $0" 1 2 就是脚本中的预设变量 一个脚本中的预设变量是没有限制的,0表示脚本文件本书 # sh option.sh 1 2 3 执行此命令输出内容如下所示: 1 2 3 option.sh 5shell中的逻辑判断 不带else的if 注意if后面的判断语句要用(())否则会报错 #! /bin/bash read -p "Please input your score: " a if ((a<60)); then echo "You didn't pass the exam." fi 5.1带else 实例代码如下 #! /bin/bash read -p "Please input your score: " a if ((a<60)); then echo "You didn't pass the exam." else echo "Good! You passed the exam." fi 5.2带有else if(这是c中的说法)在shell中表示为elif #! /bin/bash read -p "Please input your score: " a if ((a<60)); then echo "You didn't pass the exam." elif ((a>=60)) && ((a<85)); then echo "Good! You passed the exam." else echo "Very good! Your score is very heigh" fi 5.3case 逻辑判断 #! /bin/bash read -p "Input a number: " n a=$[$n%2] case $a in 1) echo "The number is odd." ;; 0) echo "The number is even." ;; *) echo "It's not a number" ;; esac * 表示其他值 6for循环 实例代码如下: #! /bin/bash for file in `ls`;do echo $file done 7while 循环 #! /bin/bash a=5 while [ $a -ge 1 ]; do echo $a a=$[$a-1] done
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