Find Linux RAM Information Command

How do I find out ram information under Linux operating systems?

You can use the following commands to find information about RAM under Linux operating systems.

Find Used and Free RAM Info Command

You need to use the free command:
# free
# free -m

             total       used       free     shared    buffers     cached
Mem:          7930       4103       3826          0         59       2060
-/+ buffers/cache:       1983       5946
Swap:        15487          0      15487

(Fig. 01: Display amount of free and used memory in the system)

Find Out Ram Speed, Make, Form Factor, Type and Other Information

You need to use the dmidecode command:
# dmidecode --type 17
OR
# dmidecode --type memory
OR
# dmidecode -t 17
Sample outputs:

 # dmidecode 2.11
SMBIOS 2.5 present.
Handle 0x0017, DMI type 17, 27 bytes
Memory Device
 Array Handle: 0x0016
 Error Information Handle: No Error
 Total Width: 72 bits
 Data Width: 64 bits
 Size: 2048 MB
 Form Factor: DIMM
 Set: 1
 Locator: DIMM1A
 Bank Locator: Bank1
 Type: DDR2
 Type Detail: Synchronous
 Speed: 667 MHz
 Manufacturer: 5185
 Serial Number: 05009F22
 Asset Tag: Not Specified
 Part Number: 72T232220HFA3SB

(Fig. 01: Finding RAM Speed, Manufacturer, Type such as DDR2, and other info)