Introduction to Linux

A Hands on Guide

Some commands have multiple man pages. For instance, the passwd command has a man page in section 1 and another in section 5. By default, the man page with the lowest number is shown. If you want to see another section than the default, specify it after the man command:

man 5 passwd

If you want to see all man pages about a command, one after the other, use the -a to man:

man -a passwd

Table 3-1. File types in a long list

Linux generally counts on having twice the amount of physical memory in the form of swap space on the hard disk. When installing a system, you have to know how you are going to do this. An example on a system with 512 MB of RAM:

• 1st possibility: one swap partition of 1 GB

• 2nd possibility: two swap partitions of 512 MB

• 3rd possibility: with two hard disks: 1 partition of 512 MB on each disk.

The last option will give the best results when a lot of I/O is to be expected.

When non-critical data is separated on different partitions, it usually happens following a set pattern:

• a partition for user programs (/usr)

• a partition containing the users' personal data (/home)

• a partition to store temporary data like print- and mail-queues (/var)

• a partition for third party and extra software (/opt)

For convenience, the Linux file system is usually thought of in a tree structure. On a standard Linux system you will find the layout generally follows the scheme presented below.

Color-ls default color scheme

• A quick guide to DVD authoring
  

• Access your ext2 and ext3 partitions from Vista
  

• Access Your MySQL Server Remotely Over SSH
  

• An Ubuntu guide to taming the Linux kernel
  

• Analyze Network Protocols With Wireshark on Ubuntu
  

• Apache, MySQL & PHP on Ubuntu
  

• Automated backups in Linux
  

• Backing up in Ubuntu is Finally Made Simple: TimeVault
  

• Become a digital video editing guru using Linux tools
  

Extend Amarok with useful scripts

Pimp your Amarok: 13 Scripts You Should Know About

Building a highly functional desktop with lightweight software

The Total Growth of Open Source

Abstract

Software development is undergoing a major change away from a fully closed software process towards a process that incorporates open source software in products and services. Just how significant is that change? To answer this question we need to look at the overall growth of open source as well as its growth rate. In this paper, we quantitatively analyze the growth of more than 5000 active and popular open source software projects. We show that the total amount of source code as well as the total number of open source projects is growing at an exponential rate. Previous research showed linear and quadratic growth in lines of source code of individual open source projects. Our work shows that open source is expanding into new domains and applications at an exponential rate.

where these settings actually reside and what they mean.  
The first set of four are located in /proc/sys/net/core.   They are:

1. rmem_default - Receive Window default value


2. rmem_max - Receive Window maximum value


3. wmem_default - Send Window default value


4. wmem_max - Send Window maximum value

add the following to /etc/sysctl.conf (substituting your window size in
place of 524288, if necessary):

# Tweaks for faster broadband...

net.core.rmem_default = 524288

net.core.rmem_max = 524288

net.core.wmem_default = 524288

net.core.wmem_max = 524288

net.ipv4.tcp_wmem = 4096 87380 524288

net.ipv4.tcp_rmem = 4096 87380 524288

net.ipv4.tcp_mem = 524288 524288 524288

net.ipv4.tcp_rfc1337 = 1

net.ipv4.ip_no_pmtu_disc = 0

net.ipv4.tcp_sack = 1

net.ipv4.tcp_fack = 1

net.ipv4.tcp_window_scaling = 1

net.ipv4.tcp_timestamps = 1

net.ipv4.tcp_ecn = 0

net.ipv4.route.flush = 1

Then to have the settings take effect immediately, run:

sysctl -p

Concurrent Booting

About

Concurrent booting allows Ubuntu to take advantage of dual-core processors, as well as processors that hyperthread or multithread or what ever the different companies call it now.

Tweak

• These settings are located in your /etc/init.d/rc file. Lets open it up.

• Look through the file and you will find ”CONCURRENCY=none”. You want to change it to:

And you’re done.

Swapping

About

Swappiness takes a value between 0 and 100 to change the balance between swapping applications and freeing cache. At 100, the kernel will always prefer to find inactive pages and swap them out; in other cases, whether a swapout occurs depends on how much application memory is in use and how poorly the cache is doing at finding and releasing inactive items.

The default swappiness is 60. A value of 0 gives something close to the old behavior where applications that wanted memory could shrink the cache to a tiny fraction of RAM. For laptops which would prefer to let their disk spin down, a value of 20 or less is recommended.

Tweak

• First we have to gain access to your /etc/sysctl.conf file.

• Just scroll to the bottom of the page and add the tag listed below. The number you want depends on how much ram you have and what you do with your system. Please read the about above this to make your decision. I have mine set to 0 on a dual core laptop with 1 gig of ram and have seen no issues and a good performance gain.

And you’re done.

Broadband Internet

About

These are various tweaks taken from various places. Here is an article that explains them all if you would like to read it in depth.

Tweak

• You have to open your /etc/sysctl.conf file back up again.

• Then again, scroll to the bottom and just add these lines to it.

• You have to reset your sysctl for these to take effect.

And you’re done.

• Obtaining a Linux System


• Installation Walkthrough


• How Linux Works


• Desktop Environment


• Command Line


• Software Equivalents

Table 3-11. File permissions

Table 3-9. File protection with chmod

Table 3-3. Most common configuration files