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dmidecode Command in Linux
The Linux dmidecode command prints the DMI table contents in a human-readable format. The DMI table, also known as the Desktop Management Interface table, tracks the system hardware components such as processor, memory, and I/O ports. It is a part of the system management BIOS (SMBIOS).
Table of Contents
Here is a comprehensive guide to the options available with the dmidecode command −
- Syntax of dmidecode Command
- dmidecode Command Options
- Understanding dmidecode Command Output
- Examples of dmidecode Command in Linux
Syntax of dmidecode Command
The general syntax for using the dmidecode command is as follows −
dmidecode [options]
The [options] field is used to manage the output behavior of the command.
dmidecode Command Options
The options used with the dmidecode command are listed in the table below −
| Flag | Option | Description |
|---|---|---|
| -d file | --dev-mem file | It reads memory from the device file; the default is /dev/mem |
| -q | --quiet | It displays output in a less verbose form |
| -s keyword | --string keyword | It displays the value of specified DMI keywords, such as bios-release-date, system-manufacturer, and chassis version (If an invalid keyword is given then a list of valid keywords will appear) |
| -t type | --type type | It only displays the entries of the specified type such as bios, system, processor, memory |
| -u | --dump | It dumps the contents in the hexadecimal format which helps in debugging |
| --dump-bin file | It dumps the entries to a file in binary format | |
| --from-dump file | It reads the DMI data dumped in a binary file | |
| -h | --help | It displays the usage help about command |
| -V | --version | It displays the command version |
Understanding the dmidecode Command Output
The dmidecode command output has different components. Let’s take an example of the following output.
In the output given below, the system boot information is retrieved. The system boot type ID is 32 (all type IDs are given in the table below).
Each entry has two sections, a DMI Header and a DMI Data.
DMI Header − It has three values −
- Handle − It is a unique identifier for the table entry (0x2000)
- Type − It indicates the hardware component type by an ID (32 system boot)
- Size − It shows the size of the record (11 bytes)
DMI Data − It contains details about the entry record such as Hardware Manufacturer, Vendor, Part Number, and other relevant information.
Examples of dmidecode Command in Linux
This section demonstrates the usage of the dmidecode command in Linux through various examples −
- Displaying all DMI Table Entries
- Displaying DMI Table Entry by a Keyword
- Displaying DMI Table Entry by a Type
- Displaying the DMI Table Entries in Hexadecimal Format
- Dumping the DMI Table Entries to a File in Binary Format
Displaying all DMI Table Entries
To display all the entries of the DMI table, execute the dmidecode command with sudo privileges −
sudo dmidecode
To get output in scrollable format, pipe the output to the less command −
sudo dmidecode | less
Press q to exit the scrollable output.
To display less verbose output, use the following option −
sudo dmidecode -q
Displaying DMI Table Entry by a Keyword
To print the DMI value of a specific keyword, the -s, or --string option is used with the keyword. All the keywords are listed in the following table −
| S. No. | Keywords |
|---|---|
| 1 | bios-vendor |
| 2 | bios-version |
| 3 | bios-release-date |
| 4 | bios-revision |
| 5 | firmware-revision |
| 6 | system-manufacturer |
| 7 | system-product-name |
| 8 | system-version |
| 9 | system-serial-number |
| 10 | system-uuid |
| 11 | system-sku-number |
| 12 | system-family |
| 13 | baseboard-manufacturer |
| 14 | baseboard-product-name |
| 15 | baseboard-version |
| 16 | baseboard-serial-number |
| 17 | baseboard-asset-tag |
| 18 | chassis-manufacturer |
| 19 | chassis-type |
| 20 | chassis-version |
| 21 | chassis-serial-number |
| 22 | chassis-asset-tag |
| 23 | processor-family |
| 24 | processor-manufacturer |
| 25 | processor-version |
| 26 | processor-frequency |
To print the processor frequency, use the following option −
sudo dmidecode -s processor-frequency
To print system UUID, use the following option −
sudo dmidecode -s system-uuid
To print the BIOS release date, use the following option −
sudo dmidecode -s bios-release-date
In the same way, any value can be printed.
Displaying DMI Table Entry by a Type
The DMI table displays the output by the type ID or simply mentioning the type keyword with the -t or --type option. A list of all type IDs is given in the following table −
| Type | Description |
|---|---|
| 0 | BIOS |
| 1 | System Board |
| 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 Association |
| 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 |
| 40 | Additional Information |
| 41 | Onboard Device |
A list of type keywords is given in the table below −
| Keywords | Equivalent Type IDs |
|---|---|
| bios | 0 |
| system | 1, 12, 15, 23, 32 |
| baseboard | 2, 10, 41 |
| chassis | 3 |
| processor | 4 |
| memory | 5, 6, 16, 17 |
| cache | 7 |
| connector | 8 |
| slot | 9 |
To display the entries of type bios, use −
sudo dmidecode -t bios
To display entries of multiple types, mention the type IDs separated by a comma −
sudo dmidecode -t 16,32
Displaying the DMI Table Entries in Hexadecimal Format
To display DMI table entries in hexadecimal format, the -u or --dump option is used. This option is mainly used for debugging purposes −
sudo dmidecode -u
Dumping the DMI Table Entries to a File in Binary Format
The --dump-bin option uses the file name to store the DMI output in binary format to a file.
sudo dmidecode --dump-bin output.bin
The binary output is useful to process the data by a script or software.
To read the binary file, use --from-dump with the filename −
sudo dmidecode --from-dump output.bin
Conclusion
The Linux dmidecode command is a useful command-line utility for displaying system hardware-related information in a human-readable format. This information can also be saved in both hexadecimal or binary formats. These formats are useful for debugging the system or parsing hardware data with a script or software for further processing.
This tutorial covered the dmidecode command in detail, such as its syntax, options, and usage in Linux with examples.