Linux Tutorials - Herong's Tutorial Examples - v5.43, by Herong Yang
"free" - Display Free and Used Memory
This section provides a tutorial example on how to display free and used memory information using the 'free' command on Linux systems.
Another important information about your Linux system is the memory. You can use the "free" command to display memory statistics including free and used memory sizes. Here are some examples of "free" command output on my CentOS computer.
1. Display memory information using "free" with default options. The memory counts are displayed in kibibytes (1,024 bytes). Note that a kibibyte (1,024 bytes) is slightly different than a kilobyte (1,000 bytes).
herong$ free total used free shared buff/cache available Mem: 7789220 2047412 677256 297448 5064552 5145248 Swap: 8085500 0 8085500
2. To control the unit, you can use "free -b|k|m|g" options.
herong$ free -m total used free shared buff/cache available Mem: 7606 1999 661 290 4945 5024 Swap: 7895 0 7895
3. Or you can use "free -h" to display counts in human readable formats.
herong$ free -h total used free shared buff/cache available Mem: 7.4Gi 2.0Gi 661Mi 290Mi 4.8Gi 4.9Gi Swap: 7.7Gi 0B 7.7Gi
The output columns are defined as:
Table of Contents
►Introduction to Linux Systems
"uname" - Display System Information
►"free" - Display Free and Used Memory
Cockpit - Web Portal for Administrator
SELinux - Security-Enhanced Linux
SSH Protocol and ssh/scp Commands
Software Package Manager on CentOS - DNF and YUM
vsftpd - Very Secure FTP Daemon
Postfix - Mail Transport Agent (MTA)
Dovecot - IMAP and POP3 Server
Email Client Tools - Mail User Agents (MUA)