[CentOS] Kickstart issue: 'dialog' doesn't work in %post, CentOS 5.5

[Zhang Huangbin]

On Jun 9, 2010, at 5:39 PM, John Doe wrote:

> From: Zhang Huangbin <zhbmaillistonly at gmail.com>
>> I'm trying to customize a CentOS installation cd, but got 
>> trouble with kickstart.
>> I want to use dialog[1] for command line based 
>> user interface, but it can't display correctly in kickstart with CentOS 5.5. 
>> Same ks file works with CentOS 5.3 (both i386 and x86_64).
> 
> What does "can't display correctly" mean?
> Checked /etc/termcap for available terminals?

I found below lines here: http://fedoraproject.org/wiki/Anaconda/Kickstart

# ====
If your script spawns a daemon process, you must make sure to close stdout and stderr. Doing so is standard procedure for creating daemons. If you do not close these file descriptors, the installation will appear hung as anaconda waits for an EOF from the script.
# ====

Will it cause my issue? and how can i close stdout and stderr?