Chapter 2. The

proc

File System

25

Running the

apm  v

command on such a system results in output similar to this:

APM BIOS 1.2 (kernel driver 1.16)

AC on line, no system battery

For systems which do not use a battery as a power source,

apm

is able do little more than put the

machine in standby mode. The

apm

command is much more useful on laptops. For example, the

following output is from the command

cat /proc/apm

on a laptop running Red Hat Linux while

plugged into a 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 contents of the

apm

file change to something like this:

1.16 1.2 0x03 0x00 0x00 0x01 99% 1792 min

The

apm  v

command will now yield more useful data, such as the following:

APM BIOS 1.2 (kernel driver 1.16)

AC off line, battery status high: 99% (1 day, 5:52)

2.2.2.

/proc/cmdline

This file shows the parameters passed to the kernel at the time it is started. A sample

/proc/cmdline

file looks like this:

ro root=/dev/hda2

This tell us the kernel is mounted read only   signified by

(ro)

  off of the second partition on the

first IDE device (

/dev/hda2

).

2.2.3.

/proc/cpuinfo

This virtual file identifies the type of processor used by your system. The following is an example of

the output you would typically see from

/proc/cpuinfo

:

processor

: 0

vendor_id

: AuthenticAMD

cpu family

: 5

model

: 9

model name

: AMD K6(tm) 3D+ Processor

stepping

: 1

cpu MHz

: 400.919

cache size

: 256 KB

fdiv_bug

: no

hlt_bug

: no

f00f_bug

: no

coma_bug

: no

fpu

: yes

fpu_exception

: yes

cpuid level

: 1

wp

: yes

flags

: fpu vme de pse tsc msr mce cx8 pge mmx syscall 3dnow k6_mtrr

bogomips

: 799.53