Shell入门学习

Env 输出系统变量

$ echo $HOME
/home/zhangyc

设置PATH
/etc/profile
PATH=$PATH:.    原有path加上当前路径"."
export PATH
这样通过xxx.sh可以直接执行shell

#The First shell
#echo "please enter your name:"
#read fname
#echo ${fname}
s=xxx
echo $s
echo "the data is " `date`
expr 4 + 5
echo $((4+5))

#命令行读写
#!/bin/bash
echo "please enter total number"
read totalNumber
echo "please enter resolve number"
read resNumber
echo $((totalNumber - resNumber))

#条件分支
echo "please enter score:"
read score
if [ $score -lt 80 ]
then 
	echo "wrong"
elif [ $score -ge 80 -a $score -lt 90 ]
then 
	echo "good"
else 
	echo "very good"
fi

#switch
echo "service: "
echo -n "1) ls"
echo -n "2) ls -l"
echo -n "3} Exit"
echo "please choice[1-3]"

read choice
case $choice in
	1) ls;;
	2) ls -l;;
	3) exit;;
	*) echo "wrong input";;
esac

#循环
ecode=1000
while [ $ecode -le 1002 ]
do
	echo "please enter employee info ecode=$ecode"
	echo -n "enter name:" #加入-n后，不换行
	read name
	echo -n "enter email:"
	read email
	echo "name:$name email:$email" >> employee.dat
	((ecode=$ecode+1))
done

#输出执行时间
time find /etc/ -name passed
#在后台运行
find /etc/ -name passed &