shell-script的简单举例

#!/bin/bash
#defind the path
PATH=/usr/local
export PATH
read -p "please input your first name:" firstname
reap -p "please input your last name:" lastname
echo -e "
your name is: $firstname $lastname"

#use date create file
read -p "please input your filename:" fileuser
filename=${fileuser:-"filename"}
#use date get the filename
date1=$(date --date='2 days ago' +%Y%m%d)
date2=$(date --date='1 days ago' +%Y%m%d)
date3=$(date +%Y%m%d)
file1=${filename}${date1}
file2=${filename}${date2}
file3=${filename}${date3}
touch "$file1"
touch "$file2"
touch "$file3"

#条件判断式
read -p "please input (Y/N): " yn
if [ "$yn"=="Y" ] || [ "$yn"=="y" ] ; then
    echo "OK continue"
    exit 0
fi
if [ "$yn"=="N" ] || [ "$yn"=="n" ] ; then
    echo "OK continue"
    exit 0
fi
#第二种情况
if [条件判断式]; then 
   内容
else
    内容
fi    
#三
if [条件判断式]; then 
   内容
elif [条件判断式]; then
    内容
else
    内容
fi

#利用case...esac判断
case $变量名称 in
   "第一个变量内容")
   程序段
   ;;
   "第二个变量内容")
   程序段
   ;;
   *)
   程序段（不包含第一和第二个变量内容中的）
   exit 1 
   ;;
esac

#举例
case $1 in
   "one")
   echo "This is one"
   ;;
   "two")
   echo "this is two"
   ;;
   "three")
   echo "This is three"
   ;;
   *)
   echo "no number"
   ;;
esac

#利用function功能（shell script执行方式是 由上而下，由左至右，所以function函数一定要写在程序的最前边）

function printit(){
   echo -n "Your choice is "
}