Win跟换了用户登陆使用cywin报告如下错误：
cygwin提示自己所在的组变成了”mkpaswd”, 这说明/etc/passwd或者/etc/group需要重建了。
Your group is currently "mkgroup". This indicates that neither
your gid nor your pgsid (primary group associated with your SID)
is in /etc/group.
The /etc/group (and possibly /etc/passwd) files should be rebuilt.
See the man pages for mkpasswd and mkgroup then, for example, run
mkpasswd -l [-d] > /etc/passwd
mkgroup -l [-d] > /etc/group
Note that the -d switch is necessary for domain users.
原因是新的登陆用户信息不在/etc/passwd和/etc/group中导致的：
运行mkpasswd -l >/etc/passwd; mkgroup -l >/etc/group即可修复。