————《鸟哥的Linux私房菜——基础篇》学习笔记

ubuntu默认的sh是连接到dash，而我们写shell脚本时使用的时bash。bash和dash在一些方面是不兼容的。因此执行同一个脚本，两者结果不一样，可能用./*sh可以执行，而sh *.sh报错。

为了正确实行使用./*.h 或者  bash *.sh  或者把==换成=（不兼容部分）

也可以直接让系统不使用dash。。。。Ubuntu之所以使用dash是因为其体积小，兼容性高，但是悲催的时，一些bash可执行的脚步在dash下不能执行了。

鸟哥私房菜13章学习shell script 中2.2节有一个例子sh06.sh

#!/bin/bash#Program# "test the func of []"#History:#2014-08-14     Windeal#version        1#All rights reserved;PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/binexport PATHread -p "Please enter (y/n):" yn[ "$yn" == "Y" -o "$yn" == "y" ] && echo "your input is y" && exit 0[ "$yn" == "N" -o "$yn" == "n" ] && echo "your input is n" && exit 0echo "I don't know what you choice\n"~     

windeal@ubuntu:~/Windeal/shell$ sh sh06.sh 
Please enter (y/n):y
sh06.sh: 12: [: y: unexpected operator
sh06.sh: 13: [: y: unexpected operator
I don't know what you choice

windeal@ubuntu:~/Windeal/shell$ 

windeal@ubuntu:~/Windeal/shell$ ./sh06.sh 
Please enter (y/n):y
your input is y
windeal@ubuntu:~/Windeal/shell$