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The Linux System Administrator's Guide: Version 0.7 | ||
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4.7. The /proc
filesystem
The /proc
filesystem contains a
illusionary filesystem. It does not exist on a disk. Instead, the
kernel creates it in memory. It is used to provide information
about the system (originally about processes, hence the name). Some
of the more important files and directories are explained below.
The /proc
filesystem is described in more
detail in the proc
manual page.
/proc/1
A directory with information about process number 1. Each process has a directory below
/proc
with the name being its process identification number./proc/cpuinfo
Information about the processor, such as its type, make, model, and performance.
/proc/devices
List of device drivers configured into the currently running kernel.
/proc/dma
Shows which DMA channels are being used at the moment.
/proc/filesystems
Filesystems configured into the kernel.
/proc/interrupts
Shows which interrupts are in use, and how many of each there have been.
/proc/ioports
Which I/O ports are in use at the moment.
/proc/kcore
An image of the physical memory of the system. This is exactly the same size as your physical memory, but does not really take up that much memory; it is generated on the fly as programs access it. (Remember: unless you copy it elsewhere, nothing under
/proc
takes up any disk space at all.)/proc/kmsg
Messages output by the kernel. These are also routed to syslog.
/proc/ksyms
Symbol table for the kernel.
/proc/loadavg
The `load average' of the system; three meaningless indicators of how much work the system has to do at the moment.
/proc/meminfo
Information about memory usage, both physical and swap.
/proc/modules
Which kernel modules are loaded at the moment.
/proc/net
Status information about network protocols.
/proc/self
A symbolic link to the process directory of the program that is looking at
/proc
. When two processes look at/proc
, they get different links. This is mainly a convenience to make it easier for programs to get at their process directory./proc/stat
Various statistics about the system, such as the number of page faults since the system was booted.
/proc/uptime
The time the system has been up.
/proc/version
The kernel version.
Note that while the above files tend to be easily readable
text files, they can sometimes be formatted in a way that is not
easily digestible. There are many commands that do little more than
read the above files and format them for easier understanding. For
example, the free program reads
/proc/meminfo
and converts the amounts given in
bytes to kilobytes (and adds a little more information, as
well).