Shell 随笔3

If 语法

if [ condition ]
   then
      commands
fi

if then else

if [ condition ]
    then
         commands
else
         commands
fi

if then elseif

if [ condition ]
    then
         commands1
elif
    then       
         commands2
......
else
         commandsx
fi

条件符号使用双圆括号，可以在条件中植入数学表达式

双方括号，可以在条件中使用通配符

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for 循环语句

for var in value1 value2 ......
    do
        commands
done

C式命令

for ((变量；条件；自增减运算))
    do
        代码块
done

控制循环:

sleep N

continue ：本次循环到此为止，可以开始下一次循环

break：跳出循环

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while 循环 ---不知道循环多少次，建议用while

while [ condition ]
do
    commands
done

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case多条件分支语句