Generate a Certificate Signing Request(CSR) with OpenSSL / Linux



Convert PDF to Images in Linux via Command Line

program to convert PDF files into HTML, XML and PNG images


Debian User install pdftohtml using following command:

Red Hat / Fedora user install pdftohtml using following command:

More details:

Unable to start firewalld, Active: failed (Result: timeout)


Try to start firewalld service via the following command

but get the following error after few seconds no response:


Execute the following command to restart firewalld service


How to Install NGINX and PHP 7.3 with PHP-FPM on RHEL/CentOS 7

Basic Server Setup

Setup Default PHP Version


Update Configuration

Create Virtual Hosts

Setup Firewall (Optional)

SELinux Settings (Optional for SELinux enabled)

Reboot after Setup

How to Install MySQL 8.0 on RHEL/CentOS 7

Basic Server Setup

Setup MySQL 8.0

Setup Firewall (Optional)

Reboot after Setup

Optional Settings for MySQL 8.0

Disable MySQL Strict Mode


Fix MySQL Password Expired

To establish a global policy such that passwords never expire.

Update /etc/my.cnf


How to enlarge CentOS 7 persistent disk size in Google Cloud

Update Disk Size

Update Partition Size

Update Volumn Size



Install and Secure Redis on CentOS 7


Redis Installation

Add the EPEL repository, and update YUM


Install Redis


Start Redis and setup automatically start Redis on boot


Verify the Installation

If Redis is running, it will return: PONG


Redis Configuration

Password settings

find and uncomment the requirepass line in the configuration file, and replace master_password with a secure password


Firewall settings


Local Benchmark Test


Check Redis Version


Setup PHP session to Redis



Install wkhtmltopdf & wkhtmltoimage to CentOS with Chinese & Asian fonts support

Install dependencies


Install wkhtmltopdf and wkhtmltoimage

p.s. you can find more versions in the following link:


Install  Chinese & Asian fonts support