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Note
In most cases, the content of the files listed in this section are not the same as
those installed on your machine. This is because much of the information is
specific to the hardware on which Red Hat Enterprise Linux is running for this
documentation effort.
2.1.
/proc/apm
This file provides information about the state of the Advanced Power Management (APM)
system and is used by the
power source, this virtual file would look similar to the following:
1.16 1.2 0x07 0x01 0xff 0x80 -1% -1 ?
Running the
command on such a system results in output similar to the following:
apm -v
APM BIOS 1.2 (kernel driver 1.16ac) AC on-line, no system battery
For systems which do not use a battery as a power source,
the machine in standby mode. The
the following output is from the command
power outlet:
1.16 1.2 0x03 0x01 0x03 0x09 100% -1 ?
When the same laptop is unplugged from its power source for a few minutes, the content of the
file changes to something like the following:
apm
1.16 1.2 0x03 0x00 0x00 0x01 99% 1792 min
The
command now yields more useful data, such as the following:
apm -v
APM BIOS 1.2 (kernel driver 1.16) AC off-line, battery status high: 99% (1
day, 5:52)
2.2.
/proc/buddyinfo
This file is used primarily for diagnosing memory fragmentation issues. Using the buddy
algorithm, each column represents the number of pages of a certain order (a certain size) that
are available at any given time. For example, for zone DMA (direct memory access), there are
command. If a system with no battery is connected to an AC
apm
command is much more useful on laptops. For example,
apm
cat /proc/apm
is able do little more than put
apm
on a laptop while plugged into a
/proc/apm
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