apache的userdir模块：http://httpd.apache.org/docs/2.2/howto/public_html.html

以前没用过，想用一下，可是就是很403，日志也是简单的
Permission denied: access to /~username denied

后来在另一台用yum安装的服务器上找到答案。
# The path to the end user account ‘public_html’ directory must be
# accessible to the webserver userid. This usually means that ~userid
# must have permissions of 711, ~userid/public_html must have permissions
# of 755, and documents contained therein must be world-readable.
# Otherwise, the client will only receive a “403 Forbidden” message.