CentOS 7

CentOS 7 is a Linux distribution that provides a free, enterprise-class, community-supported computing platform functionally compatible with its upstream source, Red Hat Enterprise Linux

You can download OS images at https://www.centos.org/download/

Steps to install CentOS 7

• Install htop on CentOS 7 / CentOS 8

In my case, followings are the steps when I setup CentOS 8.

1. Install htop on CentOS 8
2. Install lynx on CentOS 8
3. Set Hostname on CentOS 8
4. Set static IP address on CentOS 8
5. Enable/disable network interface on CentOS 8
6. Configure Firewall on CentOS 8
7. Remove/Manage services on CentOS 8

Topics associated with Centos

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  503 Service Unavailable Error displayed in Apache Reverse Proxy environment — If you see 503 Service Unavailable Error in Apache Reverse Proxy Environment with the perfect settings, it might be something associated with server security - it can be solved by /usr/sbin/setsebool
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  CentOS 7 — CentOS 7 is a Linux distribution that provides a free, enterprise-class, community-supported computing platform functionally compatible with its upstream source, Red Hat Enterprise Linux
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  CentOS warning: setlocale: LC_CTYPE: cannot change locale (UTF-8): No such file or directory on CentOS 7 — If you faced an error "cannot change locale (UTF-8)", it can be simply solved to add following lines at /etc/environment
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  Change MySQL port number — The default port that MySQL database server is running under Linux and Unix is 3306/TCP. In order to change the default MySQL/MariaDB database port in Linux, open MySQL server configuration file for editing by issuing the below command.
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  Changing GitLab repository — In order to change the data directory, you need to add git_data_dirs in /etc/gitlab/gitlab.rb
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  Check CPU - is AMD or Intel? — In CentOS 7, CPU information is stored in /proc/cpuinfo, so you can implement to acquire CPU information in the system.
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  Check network port is open or not on CentOS 7 — To check listening port on CentOS 7, you can do it by "netstat" simply, or you can try it by "ss". I was easily able to check which port is open or not on CentOS 7.
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  Checking apache web server (httpd) version on CentOS 7
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  chmod by type (directory and file permission) — To change permission by type (directory or file), the easiest way can do it is using find command and do something as a follow up action.
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  Copy updated/new files if the date is no later than the target in Linux — You can backup the latest updated/new files by cp command in Linux(CentOS 7)
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  Count number of HTTP threads in CLI — You may want to check the traffics in your server prom time to time, and checking CPU and number of threads are actually essential.
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  Count number of process in Linux shell — In some cases, you may want to know the number of processes working in the system. You can know it by grep -ef | grep <process name> | wc -l
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  Count number of processes and do something in PHP — You can limit number of cron jobs, if you use PHP for DevOps software in CentOS 7, which can be easily implemented by checking process by shell_exec.
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  Downgrade PHP from version 7.3 to 7.2 on CentOS — You can downgrade PHP from version 7.3. to 7.2 by yum and yum-config-manager.
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  Enable CORS in httpd.conf — Due to security reason, some platform does not allow to access files on apache web server that is super great feature in order not to make server in-stable, but some device having no domain connection may have no solution when requiring in communicating with such kind of servers. To resolve that issue, you will need to enable CORS in httpd.conf