php generated file https downloaded from ie pop up an error dialog

When php generates a file to download from ie in a https connection, by default it will pop up an error dialog box saying:

unable to open this internet site. the requested site is either unavailable or cannot be found. please try again later.

This is pretty confusing if you suddenly run into this case while it’s totally fine in firefox, and with no problem download from http both in ie & firefox.
To fix the problem, simple add this line of code to your php script:

header("Pragma: ");

Thanks Mark point this out here.

what’s going on with the pc sound playback and recording

Here is a nice graph showing how all the sound sources are take in and mixed, and recorded on the pc:

For more details, can dig in here: http://en.wikipedia.org/wiki/Sound_card_mixer

The article also mentioned this:

Starting from Windows Vista and 7 new sound API model was introduced. There is no stereo mix or mono mix. Instead every playback device can be opened in loopback recording mode, so you can record what you hear from your speakers, headphones, digital output etc. Even if your audio card does not support it, Windows will emulate this functionality.

Seems like can record without a mixer, need some test to confirm this. And it does mention a list of software can recorder the sound without a sound card mixer:

Software for recording without Sound card mixer on Windows

* Freecorder 4 (freeware)
* Replay Music,
* Replay Media Catcher,
* Replay AV,
* Replay Video Capture,
* WM Capture
* VirtualAudioCable

keep linux server time auto updated with the ntp server

On debian, there is a nice tool to keep server time auto updated with the ntp time server. The package we are to use is ntp. After install, it will run as a daemon and keep the time auto updated.
apt-get install ntp

For another way, you can use ntpdate, after install, it won’t run as a daemon, and will only be able to sync the time when you specifically run it as:
ntpdate time.nist.gov
Or you can setup a crontab or boot time runner to keep sync when you are booting server.
And of course, to intall it, run the command:
apt-get install ntpdate

Conclusion:
ntp is an easy way to run time sync, it will sync gracefully, no extra worry beyond apt-get install.
ntpdate is a light weight solution, it won’t install as a daemon, and save the system resource. But it only gets to be synced when you run it: either boot time or from crontab or from command line.

Good background pattern resource can be use of when design a website

Yesterday, when I was trying to do something to the always background of my website, I tried to google about the background patterns, I come across these 2 nice sites. They have some pattern design really appealing, check it out if you under some circumstance want to have some good pattern like me: