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Digging Into Documentation

The documentation in your Linux system is unsurpassed in its detail and depth. It can also be a bit difficult, when first coming to Linux, to navigate your way around the documentation system. Given the wealth of information and learning the Linux documentation system provides, finding the answers you're looking for can be a great PenguinTWEAK.

There is, of course, the man command. This is used when you're looking for details on the usage and background of a specific file.

man tar

returns the man page for the tar command. This document, as you'll see, is quite long. Fortunately, man has some limited search capabilities, much like vi. To find references to subdirectories, for example, use the following :

/subdirectories

This will highlight all instances of the word subdirectories forward from your current location in the page. To continue moving forward in the document, use the "n" key to move to the [n]ext instance of the word.

If you're unsure of the command but know how it's applied, use the -k option. This displays a list of man documents by keyword:

man -k print

returns all man pages for commands containing the string "print" along with a summary of the command.

The info system has been touted as the next great improvement to man. The syntax is similar:

info tar

returns a linked page related to the tar command. You can navigate within this document, highlighting the specific areas of the tar command you're interested in, and pressing the return key to move directly to that area. info isn't fully implemented yet, but stands to provide a much richer learning experience for the user.

There's nothing in the computing world quite like the detail provided by the Linux documentation system. Learning to use it can be one of the most useful tweaks you'll make.

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Limiting Users

If you're administering a Linux system with several users, you may find it necessary to restrict the access and capabilities of those users. On a multi-user system, such restriction can be a matter of simple security. In any event, it's good to have an understanding of the tools used to create these restrictions.

Like so much else in Linux, many user access restrictions can be created or modified with a simple text file. /etc/security/limits.conf contains the following items for limiting user access:

as: address space limits
core: core file size limit
cpu: max CPU time in minutes
data: max data size in Kb
fsize: maximum filesize in Kb
locks: the maximum number of file locks a user can hold
memlock: maximum memory locked memory space in Kb
nofile: maximum number of open files
nproc: maximum number of processes
priority: the priority with which a user's processes run
stack: the maximum stack size in Kb

As you can see, /etc/security/limits.conf sets user limits at a low level. If you're a Linux administrator, this file can be a great help to controlling the use and security of your systems.

One further file is interesting, as well. /etc/security/time.conf can limit user access by time and day.

Granular security is essential on a multi-user system. Linux provides a high level of granularity in user access to assure the integrity of your system.

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Log Tool 1.2.2

http://xjack.org/logtool/

"Logtool is a syslog file parser, report generator, and monitoring utility. It takes logfiles from syslog, multilog, or other ASCII log generating sources as input from stdin, and depending on command line switches and/or config file settings, will parse and filter out unwanted messages from the logfile accordingly, and generate output in ANSI color, formatted ASCII, CSV (for spreadsheets), or HTML format. It is very handy for use in automated nightly reports, and online monitoring of logfile activity. It comes with some simple example scripts and documentation."

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Novell
Scribbled by Bob Beaudoin

"I attended BrainShare this last week, and was at the keynote which Jack Messman made the announcement of Novell products running on the Linux kernel. I feel that you were somewhat harsh in your statements. Netware is one of the most stable OS.s available. It is the availability of their services to run on another platform which others may want. Groupwise, the new apps servers. cluster servers, etc. Novell has all ready given back code to the open source community. They also have one of their employees on the Apache development team. Apache has become Web server standard for web services."

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The Future of the Linux Kernel

http://www.linux-mag.com/2003-01/kernal_01.html

"While the Linux kernel is only a tiny piece of what most of us think of as a Linux system, it's the features and characteristics of the kernel that set the limits of what an entire Linux system is capable of. As such, the kernel, the foundation of Linux, and the process that drives its development, is of great interest to many.

"A year ago, at the beginning of 2002, kernel development was in an odd state. At that time, there had been no development kernel for almost a full year as the 2.4 kernel was slowly stabilized. With no development kernel widely available, "patch pressure" -- pressure to integrate new features into the kernel -- was building, with no relief in sight, frustration levels running high, and progress seemingly at an all-time low.

"A year later, at the beginning of 2003, the outlook is much, much brighter. New code is going into the kernel, the development process as a whole is working smoothly, and the anticipated release of Linux 2.6 in just a few months seems very achievable."

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