Kernel information

[elsiddik]

Kernel Information

Many of the entries in /proc provide access to information about the
running kernel's configuration and state. Some of these entries are at
the top level of /proc; others are under /proc/sys/kernel.


Version Information

The file /proc/version contains a long string describing the kernel's
release number and build version. It also includes information about
how the kernel was built: the user who compiled it, the machine on
which it was compiled, the date it was compiled, and the compiler
release that was used--for example:



% cat /proc/version

Linux version 2.2.14-5.0 (ro...@porky.devel.redhat.com) (gcc version

egcs-2.91.66 19990314/Linux (egcs-1.1.2 release)) #1 Tue Mar 7

21:07:39 EST 2000

This indicates that the system is running a 2.2.14 release of the
Linux kernel, which was compiled with EGCS release 1.1.2. (EGCS, the
Experimental GNU Compiler System, was a precursor to the current GCC
project.)

The most important items in this output, the OS name and kernel
version and revision, are available in separate /proc entries as well.
These are /proc/sys/kernel/ostype, /proc/sys/kernel/osrelease, and /
proc/sys/kernel/version, respectively.



% cat /proc/sys/kernel/ostype

Linux

% cat /proc/sys/kernel/osrelease

2.2.14-5.0

% cat /proc/sys/kernel/version

#1 Tue Mar 7 21:07:39 EST 2000

Hostname and Domain Name

The /proc/sys/kernel/hostname and /proc/sys/kernel/domainname entries
contain the computer's hostname and domain name, respectively. This
information is the same as that returned by the uname system call,
described in Section 8.15.

Memory Usage

The /proc/meminfo entry contains information about the system's memory
usage. Information is presented both for physical memory and for swap
space. The first three lines present memory totals, in bytes;
subsequent lines summarize this information in kilobytes--for example:



% cat /proc/meminfo

total: used: free: shared: buffers: cached:

Mem: 529694720 519610368 10084352 82612224 10977280 82108416

Swap: 271392768 44003328 227389440

MemTotal: 517280 kB

MemFree: 9848 kB

MemShared: 80676 kB

Buffers: 10720 kB

Cached: 80184 kB

BigTotal: 0 kB

BigFree: 0 kB

SwapTotal: 265032 kB

SwapFree: 222060 kB

This shows 512MB physical memory, of which about 9MB is free, and
258MB of swap space, of which 216MB is free. In the row corresponding
to physical memory, three other values are presented:

· The Shared column displays total shared memory currently
allocated on the system (see Section 5.1, "Shared Memory" ).

· The Buffers column displays the memory allocated by Linux
for block device buffers. These buffers are used by device drivers to
hold blocks of data being read from and written to disk.

· The Cached column displays the memory allocated by Linux to
the page cache. This memory is used to cache accesses to mapped files.

You can use the free command to display the same memory information.