System Information Commands

df - display amount of disk space

The df command displays filesystem disk space usage for all partitions (df stands for disk free).

df -h

will give information using megabytes (M) and gigabytes (G) instead of blocks (-h means human readable).

free - display amount of free and used memory

The free command displays the amount of free and used memory in the system.

free -m

will give the information using megabytes, which is probably the most useful for current computers.

top - display top consuming processes

The top command displays information on the Linux™ system - processes that are running, system resources including CPU, RAM and swap usage, and the total number of tasks being run. To exit top, press q.

uname - print details about the current machine

The uname command with the -a option displays all system information, including machine name, kernel name and version, and other details. This command is useful for checking which kernel is in use (uname is short for UNIX™ name).

lsb_release - print details about current Linux™ release

The lsb_release with the -a option prints version information for the Linux™ release in use. For example, typing:

lsb_release -a

will display:

No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 12.10
Release:        12.10
Codename:       precise