Linux free command

The free command in Linux is used to display information about the system’s memory usage. It provides details about the total, used, free, and available memory on the system, as well as information about swap space.

Here’s an overview of how to use the free command:

  1. Basic Usage:
    To display memory usage information, simply type free in your terminal. For example:

This command will display information about the system’s memory usage.

  1. Displaying Memory Usage:
    The free command will provide output indicating the memory usage on the system. It typically displays the following information:
  • total: The total amount of physical memory (RAM) available on the system.
  • used: The amount of memory used by the system, including buffers and cached data.
  • free: The amount of memory currently available for new processes.
  • shared: The amount of memory used by shared memory segments.
  • buffers: The amount of memory used for buffer cache.
  • cached: The amount of memory used for page cache.
  • available: The estimated amount of memory that can be allocated to new processes without swapping.
  1. Displaying Swap Space:
    Additionally, the free command displays information about swap space, which is a portion of the hard disk used as virtual memory when the physical memory is exhausted. It includes the following information:
  • Swap: The total amount of swap space available on the system.
  • Used: The amount of swap space currently in use.
  • Free: The amount of swap space available for use.
  1. Example:
    Here’s an example output of the free command:
                  total        used        free      shared  buff/cache   available
   Mem:           2048          968         300         200         779         620
   Swap:          1024           10        1014

In this example, the system has 2048 MB of total physical memory (RAM). Of that, 968 MB is currently in use, 300 MB is free, 200 MB is used by shared memory segments, and 779 MB is used for buffers and page cache. The estimated available memory for new processes is 620 MB. The system also has 1024 MB of swap space, with 10 MB currently in use and 1014 MB free.

The free command provides a quick overview of the system’s memory usage, helping you monitor memory consumption and determine the available resources.

For more information about the free command and its options, you can refer to the manual page by typing man free in your terminal.