更改默认shell，需要管理员权限。。。
/user/sbin/usermod -s /bin/tcsh username
To change your Cygwin shell, you can alter the /etc/passwd file. Each line is a delimited list of user accounts, where the last entry is the shell for that user. Simply change the line that reads, for example:
abhisek:[some other stuff]:/usr/bin/bash
to:
abhisek:[some other stuff]:/usr/bin/tcsh