Linux Dmidecode Command Explained: Check BIOS, Memory and Hardware Details

Linux Dmidecode Usage
What is Dmidecode Command?
The dmidecode stands for DesktopManagement Interface Table decoder is a very handy facility for Linux administrators to retrieve detailed information about the system’s hardware components. It is used to convert the system’s DMI table into a human-readable format. It allows administrators and users to see information about the system's hardware components configuration. This tool provides information about processor, memory, BIOS, board and other components etc.

Why to Use the dmidecode Command?

When you need some information about your system hardware component on urgent basis then dmidecode is in place to solve this problem. No need to access the system components physically for retrieving the hardware information. It displays the current system configuration and maximum information of the system such as CPU support and memory. This is commonly used to ensure the hardware specifications for the inventory purposes and the hardware upgrades.


Dmidecode commands

Syntax:
#sudo dmidecode [options]
Note: some Linux or UNIX system needs root permissions to run dmidecode commands. For running these commands sudo can grant such permissions.

1. DMI Version
To check the current version of dmidecode command is
#sudo dmidecode --v
or
#sudo dmidecode -V 
2. Help Command
Help command shows the summary of all the available options and their usage.
#sudo dmidecode --help 
3. Simple Dmidecode
This command shows all the DMI information.
#sudo dmidecode 
This command provides complete output of all the available DMI information including various hardware components.
To see the information in a presentable way use more option with the dmidecode command.
# sudo dmidecode | more

DMI Types
The -t or --type option is used to filter the output for the specific DMI types. To see the supportive types just issue dmidecode command with --type.
#sudo dmidecode -t or --types

Common Types

4. BIOS Information
To display the BIOS information command is
#sudo dmidecode -t bios
or
#sudo dmidecode --type bios
DMI type ID can also be used to fetch BIOS information. Both commands display the same bios information.
#sudo dmidecode -t 0
5. Board Information
To display the baseboard information command is
#sudo dmidecode -t baseboard
or
#sudo dmidecode -t 2
6. Processor Information
To display the processor information command is
#sudo dmidecode -t processor
or
#sudo dmidecode -t 
7. Memory Information
To display the information about Physical Memory and DIMMs run the following command
#sudo dmidecode -t memory
or
#sudo dmidecode -t 6
8. Chassis Information
To display chassis information command is
#dmidecode -t chassis
or
#dmidecode -t 3
9. System Information
To get system information command is
#sudo dmidecode -t system
or
#sudo dmidecode -t 1
10. Cache Information
To check the cache information command is
#sudo dmidecode -t cache
or
#sudo dmidecode -t 7
11. Connector Information
To check the connector information command is
#dmidecode -t connector
or
#dmidecode -t 8
12. Slot Information
To check the slot information command is
#sudo dmidecode -t slot
or
#sudo dmidecode -t 9
Information using Dmidecode Keywords
String keyword is also available option to get the information about any system component. Its syntax is
#sudo dmidecode -s or sudo dmidecode --string
If only -s option is used without any DMI keyword it shows all the available valid keywords with an error message.
13. Bios Vendor
To check the bios vendor command is
#sudo dmidecode -s bios-vendor
14. BIOS Release Date
To check the bios release date command is
#sudo dmidecode -s bios-release-date
15. Bios Version
To check the bios version command is
#sudo dmidecode -s bios-version
16. System Manufacturer Information
To check the system manufacturer information command is
#sudo dmidecode -s system-manufacturer
17. System Product Name
To check the system product name command is
#sudo dmidecode -s system-product-name
18. Processor Version
To check the processor version command is
#sudo dmidecode -s processor-version
19. Processor Manufacturer
To check the manufacturer of processor command is
#sudo dmidecode -s processor-manufacturer
20. Baseboard Product Name
To check the name of baseboard command is
#sudo dmidecode -s baseboard-product-name
How to Hide Information in Output
To hide some information in the output of the dmidecode, you need to enable quiet mode. For this purpose, use the -q switch with the dmidecode command. For example to display the system information use dmidecode command with -q --quiet switch.
#sudo dmidecode -qt system
Information as Hexadecimal
To display the information in hexadecimal and ASCII, run the dmidecode command with -u switch.
#sudo dmidecode -ut memory
How to dump DMI information in a File
To dump the dmi information in file command is
#sudo dmidecode --dump-bin testfile
How to Retrieve DMI Data from the Binary File
To retrieve the dmi data from the testfile that is created with --dump-bin option, this command is used.
#sudo dmidecode --from-dump testfile
Multiple components Information
To retrieve the multiple components' information with one command, dmidecode is used with the grep or egrep switch. Commands can be combined with pipes and specify multiple patterns with grep.

Use grep to get Multiple Patterns
To get multiple information about the system, use grep with the dmidecode command.
#sudo dmidecode -t system | grep -E ‘Manufacturer|Product Name| Serial Number’

This command will show the information about the manufacturer, product name and serial number from the system section. 
How to Get Memory Type
To display information about which type of memory is installed with grep command as DDR3, DDR4. Here T will be capital in -m2 Type.
#sudo dmidecode -t memory |grep -m2 Type
Different types of Information
Different types of information output can be combined using grep with the dmidecode command, for example to display the information about the system, processor and memory the command is
# (sudo dmidecode -t system; sudo dmidecode -t processor; sudo dmidecode -t memory) | grep -E 'Manufacturer|Version|Size'
Final Thoughts

The dmidecode command is a useful tool in the toolkit of every Linux administrator. It gives deep insights of hardware information without requiring you to open the system physically. From checking the BIOS version to serial number, to identify memory slots to manufacturer details, dmidecode helps to stream line hardware audits, troubleshooting and system documentation. Always run this command with the appropriate permissions or as a root user and be careful when using this information for the automated scripts. As a Linux administrator, understanding and using dmidecode effectively can save your time, reduce hardware related guess work and enhance your ability to manage Linux systems confidently.

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