Get the serial number of a computer using command

Windows
Open a command prompt (by choosing the Command Prompt item from the Start menu, or typing cmd in the Start menu's "Run" box), and type the following:

wmic bios get serialnumber

MacOS
Go to Utilities. Open the Terminal application and type:

ioreg -l | grep IOPlatformSerialNumber

Linux
Open a shell and type:

sudo dmidecode -t system | grep Serial

Note: The user will need to have root access to the system.