Suddenly, I enter the full screen mode of firefox. I do not know which key I pressed to enter the full screen mode. I press Esc to try to exit the full screen mode but it does not work. I…

This Zeen Leaky Paywall plugin is like the Pay For Post plugin that can sell subscription for your wordpress site. After installing the plugin, you can go to Leaky Paywall/Settings/Payments to set the Paypal/Stripe information.  There is no more thing…

To sell the posts on your WordPress site, you can try this wordpress plugin. It associates a post with a woocommerce product. A visitor cannot see the content of the post until he pays for the product. Pay For Post…

S2member is a wordpress plugin for paid membership/content management. You need a way to sell your posts on WordPress. Through s2member, visitors must pay via a payment gateway like paypal before they can register an account on your website, or…

I did not even notice the existence of systemd in the past. On CentOS 6, I used commands such as “service iptables restart/start/stop” to start/stop/restart a service. I used commands such as “chkconfig iptables on” to auto-start a service at…

The problem of httpd is hard to debug because there are few ways to debug it. You can set LogLevel to debug in httpd.conf, but that does not help much in real situations. Today I encountered a weird problem that…

What uid/euid does a process get when it is started? I have misunderstood this issue for long time. In the past I thought a process gets its uid/euid from the owner of the program file. You can use “ls -l…

If you search for the usage of the sed/awk command on the Internet, you will get tons of tutorials teaching you how to use them. I have learnt sed/awk for dozen of years but still cannot write a valid sed/awk…

I’m investigating my hacked website under xampp environment. I put my website files in c:\xampp\htdocs\domainhostseotool\, and visit the site as localhost/domainhostseotool. I’m little worried about a possible security risk. Suppose the compromised website has an infected php file which contains…

Yum repositories are like websites that you can download software from. Yum has default repositories to download packages so you do not need to configure repos to use yum to install/upgrade packages on your system. But that is not enough.…