if高级用法

#!/bin/bash
#Author: www.zutuanxue.com
#Created Time:
#Script Description: 

if (( (5+5-5)*5/5 > 10 ))
    then
        echo "yes"
else
        echo "no"
fi

#!/bin/bash
#Author: www.zutuanxue.com
#Created Time: 
#Script Description: 
for var in  ab ac rx bx rvv vt
   do
       if [[ "$var" == r* ]]
	  then
		echo "$var"
       fi
done

if [ ! -d /tmp/baism ]
    then
        mkdir /tmp/baism
fi

可以简写为

[ ！ -d /tmp/baism ] && mkdir /tmp/baism

if [ $USER == 'root' ]
	  then
	      echo "hello root"
else
			  echo "hello guest"
fi

可以简写
[ $USER == 'root' ]&&echo "hello root" || echo "hello guest"