ubuntu內的sh是指到dash

在bin/內
lrwxrwxrwx 1 root root 4 Dec 6 16:29 sh -> dash

dash使用for(( i=0;i<10;i++> ))這種用法會出現
Syntax error: Bad for loop variable




解決方法是:

1. 使用bash來跑script
   bash a.sh
2. 修改~/.bashrc加入
   alias sh='bash'
   

ps. 使用dash的原因
sudo dpkg-reconfigure dash

The default /bin/sh shell on Debian and Debian-based systems is bash.
However, since the default shell is required to be POSIX-compliant, any shell that conforms to POSIX, such as dash, can serve as /bin/sh.
You may wish to do this because dash is faster and smaller than bash.