unix 权限问题： 普通用户cde登录失败

其实这些问题的引子，都是起源于我的一台u40。根源在于权限错误，但是现象千奇百怪，万紫千红。u40的表现为，root用户登录正常，而
其他普通用户，cde等图形环境，输入用户名口令后，过一会自动退到登录界面，不能登录。
telnet到该主机，使用df -k，查看各分区正常，并无分区耗尽情况。cd .dt，使用ls -lt查看文件，发现最新的文件为startlog文件，使用vi查看：
--- starting /usr/dt/bin/dtsearchpath
--- starting /usr/dt/bin/dtappgather &
--- starting /usr/dt/bin/dsdm &
--- session log file is /dev/null
--- DTSOURCEPROFILE is 'true' (see /export/home/oracle/.dtprofile)
--- execing /usr/dt/bin/dtsession with a /bin/bash login shell ...
grantpt: Permission denied
unable to get pty: Permission denied
X connection to :0.0 broken (explicit kill or server shutdown).^M
X connection to :0.0 broken (explicit kill or server shutdown).^M
y :0.0;lication 'com.sun.iiim.cle.aux.palette' lost its connection to the displa
most likely the X server was shut down or you killed/destroyed
the application.
lay :0.0;cation 'com.sun.iiim.cle.aux.composite' lost its connection to the disp
most likely the X server was shut down or you killed/destroyed
the application.
X connection to :0.0 broken (explicit kill or server shutdown).^M
Client shut down the connection owned by im_id(1).
Client shut down the connection owned by im_id(1).
Xlib: connection to ":0.0" refused by server^M
Xlib: Invalid MIT-MAGIC-COOKIE-1 key^M
/usr/openwin/bin/xlsatoms:  unable to open display ":0"
Notification Application cannot run:  User is not running
in the GNOME environment.
注意到红色部分有错误：
grantpt: Permission denied
unable to get pty: Permission denied
网上放狗，发现有高人留贴指点，则关注/usr/lib/pt_chmod权限，ls发现：
---x--x--x   1 root     bin         5776 2007   1月  9 pt_chmod
chmod u+s，恢复正常，此时pt_chmod权限如下：
---s--x--x   1 root     bin         5776 2007   1月  9 pt_chmod