The Desktop Management Interface provides a standardized description of a computer's hardware, including characteristics such as BIOS serial number and hardware connectors. dmidecode provides a dump of the DMI data available from the BIOS. It is used as a back-end tool by other hardware detection programs.
John S. says,
What I really want to recommend is dmidecode, the program. In Woody it's in ipmi-control, in Sarge it's in dmidecode.
Tells you far more than you really want to know about what's in the computer case without undressing it.
It's a good companion to lspci.
dmidecode requires lm-sensors. Although the description claims it's used as a back-end tool by other programs, there do not appear to be any other packages (in sarge) that depend on dmidecode at this time. Perhaps the description is referring to the other programs that are provided in the dmidecode package: biosdecode, ownership, and vpddecode.
More information on this package can be found on the Debian web site.
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