To check and list installed packages in CentOS Linux, you can use the rpm command with the -qa option. The rpm command is a utility that allows you to manage packages on a CentOS system, and the -qa option tells the rpm command to list all of the installed packages.
To list all of the installed packages using the rpm command, open a terminal and enter the following command:
rpm -qa
This will display a list of all of the installed packages, along with their version numbers and release numbers. The output will look something like this:
glibc-2.17-260.el7.x86_64 tzdata-2019c-1.el7.noarch vim-common-7.4.160-6.el7.x86_64 ...
To list the installed packages in a specific category, you can use the -q option followed by the category name. For example, to list the installed kernel packages, you can use the following command:
rpm -q kernel
To list the installed packages that belong to a specific group of packages, you can use the -qa option followed by the group name. For example, to list the installed development tools, you can use the following command:
rpm -qa "development tools"
Keep in mind that the rpm command only works with packages that are installed using the RPM package management system. If you have installed packages using a different package manager (such as yum or dnf), you will need to use a different method to list the installed packages.