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Dmidecode is a tool for dumping a computer’s DMI (some say SMBIOS) table contents that  described in your system BIOS in a human-readable format. This table contains descriptions of your system hardware components, as well as other useful pieces of information. Typically it includes system manufacturer, model name, serial number, BIOS version, asset tag as well as a lot of other details of varying level of interest and reliability depending on the manufacturer. This will often include usage status for the CPU sockets, expansion slots (e.g. AGP, PCI, ISA) and memory module slots, and the list of I/O ports (e.g. serial, parallel, USB).Dmidecode was first written by Alan Cox and is now being further developed and maintained by Jean Delvare. It is released under the General Public License (GPL). There’re three additional tools coming with dmidecode:

1. biosdecode prints all BIOS related information it can find (see a sample output);
2. ownership retrieves the “ownership tag” that can be set on Compaq computers;
3. vpddecode prints the “vital product data” information that can be found in almost all IBM computers (see a sample output).

Here’s a detailed blog post on how to use dmidecode in Linux at the geekstuff.com. This article provides an overview of the dmidecode and few practical examples on how to use dmidecode command. For system administrations, you might need to remember these DMI types, in order to ease some daily query work:

Following are the available DMI types (You can use them directly with the -t options like “dmidecode -t 4″):

Type   Information
----------------------------------------
0   BIOS
1   System
2   Base Board
3   Chassis
4   Processor
5   Memory Controller
6   Memory Module
7   Cache
8   Port Connector
9   System Slots
10   On Board Devices
11   OEM Strings
12   System Configuration Options
13   BIOS Language
14   Group Associations
15   System Event Log
16   Physical Memory Array
17   Memory Device
18   32-bit Memory Error
19   Memory Array Mapped Address
20   Memory Device Mapped Address
21   Built-in Pointing Device
22   Portable Battery
23   System Reset
24   Hardware Security
25   System Power Controls
26   Voltage Probe
27   Cooling Device
28   Temperature Probe
29   Electrical Current Probe
30   Out-of-band Remote Access
31   Boot Integrity Services
32   System Boot
33   64-bit Memory Error
34   Management Device
35   Management Device Component
36   Management Device Threshold Data
37   Memory Channel
38   IPMI Device
39   Power Supply

Instead of type_id, you can also pass the keyword to the -t option of the dmidecode command. Following are the available keywords:

Keyword     Types
------------------------------
bios        0, 13
system      1, 12, 15, 23, 32
baseboard   2, 10
chassis     3
processor   4
memory      5, 6, 16, 17
cache       7
connector   8
slot        9

Beware that DMI data have proven to be too unreliable to be blindly trusted. Dmidecode does not scan your hardware, it only reports what the BIOS told it to.

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