Centos

To clean the yum cache for untracked repositories, disable the untracked repositories and clean the Yum cache via the “yum clean all” command.

To enable/disable SELinux modes in CentOS, assign the “enforcing” or “disabled” value to the SELINUX parameter in the SELinux configuration file.

To change the runlevels (targets) with the systemd in CentOS, use the “systemctl set-default ” command in CentOS-based Linux distribution.

To install PHP on CentOS, use the “yum install php” command. Users can also install PHP modules by executing the “ yum install php-module-name” command.

To install, remove, query, and update RPM packages, use the “yum” command by specifying the package name in the terminal of CentOS.

CentOS / RHEL offers the “clean all” command to clean the entire YUM cache, including “metadata ”, “package headers”, and “packages” from the system.

CentOS offers the “rpm -ql ” and “rpm -qf ” commands to list all files installed from an RPM package and find the package belonging to a specific file.

CentOS offers the “yum” package manager to install the telnet via the “sudo yum install telnet” command. To configure it, enable the “telnet.socket” services.

CentOS offers the “firewall-cmd –permanent –add-port=80/tcp” command to open a port in the system. For this, configure the firewall to allow traffic.

CentOS offers the “YUM” to install a specific version of an RPM package on a system. For this, specify the “package name” and the “version”.

CentOS offers the “hostnamectl”, “hostname”, and “nmtui” commands to change the hostname. Also, users can modify the hostname from the “/etc/hostname” file.

CentOS / RHEL offers the “sysctl” configuration file and “kernel” module to disable IPv6 in the system. For this, setting the disable_ipv6 parameter to 1.

CentOS offers the “ntpdate” command with the “ntpd” service to synchronize the NTP server forcefully. It sets the system time with the time of the NTP server.

CentOS / RHEL offers the “clean all” command to clean the entire YUM cache, including “metadata ”, “package headers”, and “packages” from the system.

The “yum –downloadonly [options] [package]” command downloads a package without installing them in CentOS. Also, specify the location to download the package.

To install MySQL on CentOS 7, the “mysql-server” package is required after enabling the repository of MySQL 8.0. It installs all dependencies in the system.

To list the open ports in firewalld, the “firewall-cmd” command works with the “–list-ports” option. Before it, users ensure the active services of Firewalld.

CentOS offers the “lsb_release”, “hostnamectl”, and “uname” commands to check the CentOS version. Also, the “centos-release” file contains version information.

To check the available packages in the Yum package manager, the “yum list” and “yum info” commands are utilized in Linux System.

To uninstall a yum package, use the remove command, autoremove option, or erase command. Read this post for a practical demonstration of these methods.