Installation guide

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