Linux Shell 笔记一

最近在学习linux，在这里给大家推荐一个网站http://linux.vbird.org/ 上面关于linux的教程写得很好，也避免了我在学习过程中的很多弯路。
程序一：HelloWord,在屏幕输出HelloWord
利用vim 创建一个sh01.sh文件
echo -e "Hello World!\a\n"
exit 0

程序二：将输入参数拼接后输出
read -p "First Name:" firstname
read -p "Last Name:" lastname
echo -e "\n your full name is:$firstname $lastname"
程序三：
根据日期创建文件
echo -e "I will use touch comand to create 3 file.\n"
read -p "please input the filename what you want:" fileuser
filename=${fileuser:-"filename"}
date1=`date --date='2 days ago' +%Y%m%d`
file1="$filename""$date1"
touch $file1".log"

程序四：普通计算
[root@localhost scripts]# cat sh4.sh
read -p "first:" first
read -p "second:" second
total=$(($first*$second))
echo -e "\n========>$total"

程序五：查找文件，判定权限
[root@localhost scripts]# cat sh5.sh
echo -e "input filename"
read -p "input the filename you want:" filename
test -z $filename && echo "\filename can't be null" && exit 0
test ! -e $filename && echo "file not exist!" && exit 0
test -f $filename && filetype="regulare file"
test -d $filename && filetype="directory"
test -r $filename && perm="readable"
test -w $filename && perm="$perm writable"
test -x $filename && perm="$perm executable"
echo "The filename:$filename is a $filetype"
echo "And the permission are :$perm"

程序六：if else
[root@localhost scripts]# cat sh6.sh
echo "hello world ,shell"
[ -n "$0" ] && echo "$0" || exit 0
[ -n "$1" ] && echo "$1" || exit 0
echo "shell over!"
exit 0
#调用时采用 sh sh6.sh par1 par2
#其中sh6.sh为第一个参数
#par1为第二个参数
#$0取第一个参数，$1取第二个参数

程序7：if else(2)
[root@localhost scripts]# cat sh7.sh
read -p "yes or no (y/n)?" ny
#注意空格！！
if [ "$ny" == "Y" ] || [ "$ny" == "y" ]; then
echo "OK,continue"
exit 0
fi
if [ "$ny" == "N" ] || [