This article will guide you on how to check the #memory #usage on the #CentOS 8 system. Moreover, we have executed different commands such as cat, free, #vmstat, top and htop that are used to display the memory information. sudo apt-get clean clears out the local #repository of retrieved package files.It removes everything but the lock file from /var/cache/apt/archives/ and /var/cache/apt/archives/partial/. Another possibility to see what happens when we use the command sudo apt-get clean is to simulate the execution with the -s -option.Using these commands, you can easily get information about your system RAM, and CPU.Commands to check memory usage on Linux:1. free command. The free command is the most simple and easy to use command to check memory usage on linux.2. /proc/meminfo. The next way to check memory usage is to read the /proc/meminfo file. 3. vmstat. The vmstat command with the s option, lays out the memory usage statistics much like the proc command.5. top command.5. htop.