• 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
• In a file system, a file is represented by an inode, a kind of serial number containing information about the actual data that makes up the file: to whom this file belongs, and where is it located on the hard disk.
• It is generally considered a bad idea to connect (graphically) using the root
• GNU programs take long options, preceded by two dashes (--)

• Table 3-2. Subdirectories of the root directory

  Directory	Content
  /bin	Common programs, shared by the system, the system administrator and the users.
  /boot	The startup files and the kernel, vmlinuz. In some recent distributions also grub data. Grub is the GRand Unified Boot loader and is an attempt to get rid of the many different boot-loaders we know today.
  /dev	Contains references to all the CPU peripheral hardware, which are represented as files with special properties.
  /etc	Most important system configuration files are in /etc, this directory contains data similar to those in the Control Panel in Windows
  /home	Home directories of the common users.
  /initrd	(on some distributions) Information for booting. Do not remove!
  /lib	Library files, includes files for all kinds of programs needed by the system and the users.
  /lost+found	Every partition has a lost+found in its upper directory. Files that were saved during failures are here.
  /misc	For miscellaneous purposes.
  /mnt	Standard mount point for external file systems, e.g. a CD-ROM or a digital camera.
  /net	Standard mount point for entire remote file systems
  /opt	Typically contains extra and third party software.
  /proc	A virtual file system containing information about system resources. More information about the meaning of the files in proc is obtained by entering the command man proc in a terminal window. The file proc.txt discusses the virtual file system in detail.
  /root	The administrative user's home directory. Mind the difference between /, the root directory and /root, the home directory of the root user.
  /sbin	Programs for use by the system and the system administrator.
  /tmp	Temporary space for use by the system, cleaned upon reboot, so don't use this for saving any work!
  /usr	Programs, libraries, documentation etc. for all user-related programs.
  /var	Storage for all variable files and temporary files created by users, such as log files, the mail queue, the print spooler area, space for temporary storage of files downloaded from the Internet, or to keep an image of a CD before burning it.
• In addition to the man pages, you can read the Info pages about a command, using the info command. These usually contain more recent information and are somewhat easier to use.
• The name of the command and a short description are given, which is used for building an index of the man pages. You can look for any given search string in this index using the apropos command.

• Table 3-1. File types in a long list

  Symbol	Meaning
  -	Regular file
  d	Directory
  l	Link
  c	Special file
  s	Socket
  p	Named pipe
  b	Block device
• The only information not included in an inode, is the file name and directory. These are stored in the special directory files. By comparing file names and inode numbers, the system can make up a tree-structure that the user understands. Users can display inode numbers using the -i option to ls. The inodes have their own separate space on the disk.

• 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.
• One of the goals of having different partitions is to achieve higher data security in case of disaster. By dividing the hard disk in partitions, data can be grouped and separated. When an accident occurs, only the data in the partition that got the hit will be damaged, while the data on the other partitions will most likely survive.

• 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)
• During system startup, all the partitions are thus mounted, as described in the file /etc/fstab.
• On a running system, information about the partitions and their mount points can be displayed using the df command (which stands for disk full or disk free). In Linux, df is the GNU version, and supports the -h or human readable option which greatly improves readability.

• 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.

  Figure 3-1. Linux file system layout

  
• The kernel is on a separate partition as well in many distributions, because it is the most important file of your system. If this is the case, you will find that you also have a /boot partition, holding your kernel(s) and accompanying data files.

• Introduction to Linux

  A Hands on Guide
• 2. Quickstart
• 3. About files and the file system
• 4. Processes
• 5. I/O redirection
• 7. Home sweet /home
• 9. Fundamental Backup Techniques
• 10. Networking
• 11. Sound and Video
• B. DOS versus Linux commands
• C. Shell Features
• List of Tables

  1. Typographic and usage conventions

  2-1. Quickstart commands

  2-2. Key combinations in Bash

  2-3. New commands in chapter 2: Basics

  3-1. File types in a long list

  3-2. Subdirectories of the root directory

  3-3. Most common configuration files

  3-4. Common devices

  3-5. Color-ls default color scheme

  3-6. Default suffix scheme for ls

  3-7. Access mode codes

  3-8. User group codes

  3-9. File protection with chmod

  3-10. New commands in chapter 3: Files and the file system

  3-11. File permissions

  4-1. Controlling processes

  4-2. Common signals

  4-3. New commands in chapter 4: Processes

  5-1. New commands in chapter 5: I/O redirection

  7-1. Common environment variables

  7-2. New commands in chapter 7: Making yourself at home

  8-1. New commands in chapter 8: Printing

  9-1. New commands in chapter 9: Backup

  10-1. The simplified OSI Model

  10-2. New commands in chapter 10: Networking

  11-1. New commands in chapter 11: Audio

  B-1. Overview of DOS/Linux commands

  C-1. Common Shell Features

  C-2. Differing Shell Features
• The file /etc/shells gives an overview of known shells
• most configuration files are stored in the /etc directory. Content can be viewed using the cat command, which sends text files to the standard output (usually your monitor)
• bashrc  The system-wide configuration file for the Bourne Again SHell. Defines functions and aliases for all users.
• crontab and the cron.* directories  Configuration of tasks that need to be executed periodically - backups, updates of the system databases, cleaning of the system, rotating logs etc.
• default  Default options for certain commands, such as useradd.
• fstab  Lists partitions and their mount points.
• hosts  A list of machines that can be contacted using the network, but without the need for a domain name service. This has nothing to do with the system's network configuration, which is done in /etc/sysconfig.
• inittab  Information for booting: mode, number of text consoles etc.
• logrotate.*  Rotation of the logs, a system preventing the collection of huge amounts of log files.
• profile  System wide configuration of the shell environment: variables, default properties of new files, limitation of resources etc.
• services  Connections accepted by this machine (open ports).
• In the /var directory we find a set of directories for storing specific non-constant data (as opposed to the ls program or the system configuration files, which change relatively infrequently or never at all). All files that change frequently, such as log files, mailboxes, lock files, spoolers etc. are kept in a subdirectory of /var.
• As a security measure these files are usually kept in separate parts from the main system files, so we can keep a close eye on them and set stricter permissions where necessary. A lot of these files also need more permissions than usual, like /var/tmp, which needs to be writable for everyone. A lot of user activity might be expected here,
• The default location of all logs is /var/log

• Color-ls default color scheme

  Color	File type
  blue	directories
  red	compressed archives
  white	text files
  pink	images
  cyan	links
  yellow	devices
  green	executables
  flashing red	broken links

41 more annotations...

• Ubuntu Howtos
• • A quick guide to DVD authoring 
• • Access your ext2 and ext3 partitions from Vista 
• • Access Your MySQL Server Remotely Over SSH 
• All about Linux swap space
• All your apt cache belongs to us!
• • 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 
• Building An Ubuntu MythTV Box

11 more annotations...

• Choose the DVD ripper that's right for you

• for maximum impact, cross platform tools and languages really are the best option
• Java is always available and for the most part its “write once, run everywhere” mantra can be made to work. Python is also a popular stable.

• Be the next big thing in open source
• There’s no sense putting fingers to keyboard until you know what you want to achieve. I have a belief that the best software is borne out of genuine need.
• unless I have a clear distinctive then really I have nothing compelling

1 more annotation...

• Extend Amarok with useful scripts

   

    By Razvan T. Coloja on March 13, 2008

• Pimp your Amarok: 13 Scripts You Should Know About

    14Mar2008  Filed under: Linux:General Author: Rami Taibah

• Building a highly functional desktop with lightweight software

   

    By Razvan T. Coloja on March 14, 2008
• iDesk to give her icons on the desktop on top of the Fluxbox desktop environment
• To provide more of a GNOME look, I installed fbpanel from the Ubuntu repositories
• As a file manager I settled for the latest version of PCManFM (0.3.6.1).
• Mirage, which consumes approximatively 1% more RAM than GPicView but offers many more options.
• For video playing I used the default MPlayer with no GUI
• Next came Decibel Audio Player.
• For BitTorrent download I installed Deluge.
• As a PDF viewer I replaced Acrobat Reader with ePDFView.
• There are other software packages you can install instead of the resource-hungry applications you may be used to: Claws as an email client, Abiword to edit and read .DOC files, Gnumeric for spreadsheets, Kazehakase as an even lighter Web browser, and Graveman for burning CDs and DVDs.

8 more annotations...

• Available as a PDF file or in HTML.

• The Total Growth of Open Source

   

   

  Amit Deshpande and Dirk Riehle
   SAP Research, SAP Labs LLC

   

• 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.

•       Matthias Ettrich: The KDE-Man!                              

  Nobody in their right mind would choose Windows over GNU/Linux based on the desktop experience alone, says Matthias Ettrich.
• Where do you see KDE on Windows?
  ME: When you say KDE, there're at least three of them: the development platform, the desktop and the set of applications built on top of that platform. You will always get the best KDE experience when using all three combined.
• To me personally, two things matter the most. First, how easy is it to develop applications that really utilise the power of the underlying platform? Keep in mind that those 'desktops' really are software development platforms, what you see on the screen is just the tip of the iceberg. And second, is it free, in the liberty sense of the word? Do I get the source code? Can I learn from it? Can I modify it? Can I share my modifications with others?

1 more annotation...

• Another contains the complete history of my use of a particular computer -- all the software changes I've made, tips and tricks I discovered, and hardware issues.

• Linux users: In Gnome, you can paste text without previously copying it to the clipboard. How does this work? Glad you asked. First, highlight a chunk of text in any application, then open a new application and middle-click the mouse. The highlighted text will automatically get pasted into the active application -- bypassing the clipboard altogether! In fact, this method will not disturb the existing contents of the clipboard in any way. Talk about a time saver when copying text between applications -- like Firefox and the terminal.

• "How do I tweak Linux for broadband?"
• This document applies to kernel   2.4.x, and will also work on the 2.6.x kernel provided it is compiled with /proc file system support enabled
• RWIN (Receive WINdow) value
• in the "Linux World" this value is dynamic
• Typically, you will notice that your connection is actually slower than the default settings if your  window size is too big.   That being said, you should try out different size window sizes and see what  works best for you--but, in most cases either 512 KB, 256 KB, or 128 KB seem to do the trick quite nicely.

• 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
• The second set of eleven are located in /proc/sys/net/ipv4.

• 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

6 more annotations...

• Tweak Ubuntu for speed
• these tweaks will work with all forms of Linux
• Speed up your File System

• 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.
   
   
  1. sudo gedit /etc/init.d/rc
   
   
  • Look through the file and you will find ”CONCURRENCY=none”. You want to change it to:
   
   
  1. CONCURRENCY=shell
   

  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.
   
   
  1. sudo gedit /etc/sysctl.conf
   
   
  • 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.
   
   
  1. vm.swappiness=0
   

  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.
   
   
  1. sudo gedit /etc/sysctl.conf
   
   
  • Then again, scroll to the bottom and just add these lines to it.
   
   
  1. net.core.rmem_default = 524288
   
  2. net.core.rmem_max = 524288
   
  3. net.core.wmem_default = 524288
   
  4. net.core.wmem_max = 524288
   
  5. net.ipv4.tcp_wmem = 4096 87380 524288
   
  6. net.ipv4.tcp_rmem = 4096 87380 524288
   
  7. net.ipv4.tcp_mem = 524288 524288 524288
   
  8. net.ipv4.tcp_rfc1337 = 1
   
  9. net.ipv4.ip_no_pmtu_disc = 0
   
  10. net.ipv4.tcp_sack = 1
   
  11. net.ipv4.tcp_fack = 1
   
  12. net.ipv4.tcp_window_scaling = 1
   
  13. net.ipv4.tcp_timestamps = 1
   
  14. net.ipv4.tcp_ecn = 0
   
  15. net.ipv4.route.flush = 1
   
   
  • You have to reset your sysctl for these to take effect.
   
   
  1. sudo sysctl -p
   

  And you’re done.

4 more annotations...

• • Obtaining a Linux System
   
  • Installation Walkthrough
   
  • How Linux Works
   
  • Desktop Environment
   
  • Command Line
   
  • Software Equivalents

• Table 3-11. File permissions

  Who\What	r(ead)	w(rite)	(e)x(ecute)
  u(ser)	4	2	1
  g(roup)	4	2	1
  o(ther)	4	2	1

• The permissions are always in the same order: read, write, execute for the user, the group and the others.

• Table 3-9. File protection with chmod

  Command	Meaning
  chmod 400 file	To protect a file against accidental overwriting.
  chmod 500 directory	To protect yourself from accidentally removing, renaming or moving files from this directory.
  chmod 600 file	A private file only changeable by the user who entered this command.
  chmod 644 file	A publicly readable file that can only be changed by the issuing user.
  chmod 660 file	Users belonging to your group can change this file, others don't have any access to it at all.
  chmod 700 file	Protects a file against any access from other users, while the issuing user still has full access.
  chmod 755 directory	For files that should be readable and executable by others, but only changeable by the issuing user.
  chmod 775 file	Standard file sharing mode for a group.
  chmod 777 file	Everybody can do everything to this file.
• When a file is owned by the wrong user or group, the error can be repaired with the chown (change owner) and chgrp (change group) commands.

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• <p><b>Table 3-3. Most common configuration files</b></p><table border="1" class="CALSTABLE"><thead><tr><th align="left" valign="middle">File</th><th align="left" valign="middle">Information/service</th></tr></thead><tbody><tr><td align="left" valign="middle"><tt class="filename">aliases</tt><br/> </td><td align="left" valign="middle">Mail aliases file for use with the Sendmail and Postfix mail server. Running a mail server on each and every system has long been common use in the UNIX world, and almost every Linux distribution still comes with a Sendmail package. In this file local user names are matched with real names as they occur in E-mail addresses, or with other local addresses. <br/></td></tr><tr><td align="left" valign="middle"><br/> <tt class="filename">apache</tt><br/> </td><td align="left" valign="middle">Config files for the Apache web server.<br/> </td></tr><tr><td align="left" valign="middle"><br/> <tt class="filename">bashrc</tt><br/> </td><td align="left" valign="middle">The system-wide configuration file for the Bourne Again SHell. Defines functions and aliases for all users. Other shells may have their own system-wide config files, like <tt class="filename">cshrc</tt>.<br/></td></tr><tr><td align="left" valign="middle"><br/> <tt class="filename">crontab</tt> and the <tt class="filename">cron.*</tt> directories<br/> </td><td align="left" valign="middle">Configuration of tasks that need to be executed periodically - backups, updates of the system databases, cleaning of the system, rotating logs etc. <br/> </td></tr><tr><td align="left" valign="middle"><br/> <tt class="filename">default</tt><br/> </td><td align="left" valign="middle">Default options for certain commands, such as <b class="command">useradd</b>.<br/></td></tr><tr><td align="left" valign="middle"><br/> <tt class="filename">filesystems</tt><br/> </td><td align="left" valign="middle">Known file systems: ext3, vfat, iso9660 etc.<br/> </td></tr><tr><td align="left" valign="middle"><br/> <tt class="filename">fstab</tt><br/> </td><td align="left" valign="middle">Lists partitions and their <em>mount points</em>.<br/> </td></tr><tr><td align="left" valign="middle"><br/> <tt class="filename">ftp*</tt><br/> </td><td align="left" valign="middle">Configuration of the ftp-server: who can connect, what parts of the system are accessible etc.<br/> </td></tr><tr><td align="left" valign="middle"><br/> <tt class="filename">group</tt><br/> </td><td align="left" valign="middle">Configuration file for user groups. Use the shadow utilities <b class="command">groupadd</b>, <b class="command">groupmod</b> and <b class="command">groupdel</b> to edit this file. Edit manually only if you really know what you are doing.<br/> </td></tr><tr><td align="left" valign="middle"><br/> <tt class="filename">hosts</tt><br/> </td><td align="left" valign="middle">A list of machines that can be contacted using the network, but without the need for a domain name service. This has nothing to do with the system's network configuration, which is done in <tt class="filename">/etc/sysconfig</tt>.<br/> </td></tr><tr><td align="left" valign="middle"><br/> <tt class="filename">inittab</tt><br/> </td><td align="left" valign="middle">Information for booting: mode, number of text consoles etc.<br/> </td></tr><tr><td align="left" valign="middle"><br/> <tt class="filename">issue</tt><br/> </td><td align="left" valign="middle">Information about the distribution (release version and/or kernel info).<br/> </td></tr><tr><td align="left" valign="middle"><br/> <tt class="filename">ld.so.conf</tt><br/> </td><td align="left" valign="middle">Locations of library files.<br/> </td></tr><tr><td align="left" valign="middle"><br/> <tt class="filename">lilo.conf</tt>, <tt class="filename">silo.conf</tt>, <tt class="filename">aboot.conf</tt> etc.<br/> </td><td align="left" valign="middle">Boot information for the LInux LOader, the system for booting that is now gradually being replaced with GRUB.<br/> </td></tr><tr><td align="left" valign="middle"><br/> <tt class="filename">logrotate.*</tt><br/> </td><td align="left" valign="middle">Rotation of the logs, a system preventing the collection of huge amounts of log files.<br/> </td></tr><tr><td align="left" valign="middle"><br/> <tt class="filename">mail</tt><br/> </td><td align="left" valign="middle">Directory containing instructions for the behavior of the mail server.</td></tr><tr><td align="left" valign="middle"><br/> <tt class="filename">modules.conf</tt><br/></td><td align="left" valign="middle">Configuration of modules that enable special features (drivers).<br/> </td></tr><tr><td align="left" valign="middle"><br/> <tt class="filename">motd</tt><br/> </td><td align="left" valign="middle">Message Of The Day: Shown to everyone who connects to the system (in text mode), may be used by the system admin to announce system services/maintenance etc.<br/> </td></tr><tr><td align="left" valign="middle"><br/> <tt class="filename">mtab</tt><br/> </td><td align="left" valign="middle">Currently mounted file systems. It is advised to never edit this file.<br/> </td></tr><tr><td align="left" valign="middle"><br/> <tt class="filename">nsswitch.conf</tt><br/> </td><td align="left" valign="middle">Order in which to contact the name resolvers when a process demands resolving of a host name.<br/> </td></tr><tr><td align="left" valign="middle"><br/> <tt class="filename">pam.d</tt><br/> </td><td align="left" valign="middle">Configuration of authentication modules.<br/> </td></tr><tr><td align="left" valign="middle"><br/> <tt class="filename">passwd</tt><br/> </td><td align="left" valign="middle">Lists local users. Use the shadow utilities <b class="command">useradd</b>, <b class="command">usermod</b> and <b class="command">userdel</b> to edit this file. Edit manually only when you really know what you are doing.<br/> </td></tr><tr><td align="left" valign="middle"><br/> <tt class="filename">printcap</tt><br/> </td><td align="left" valign="middle">Outdated but still frequently used printer configuration file. Don't edit this manually unless you really know what you are doing.<br/> </td></tr><tr><td align="left" valign="middle"><br/> <tt class="filename">profile</tt><br/> </td><td align="left" valign="middle">System wide configuration of the shell environment: variables, default properties of new files, limitation of resources etc.<br/> </td></tr><tr><td align="left" valign="middle"><br/> <tt class="filename">rc*</tt><br/> </td><td align="left" valign="middle">Directories defining active services for each run level.<br/> </td></tr><tr><td align="left" valign="middle"><br/> <tt class="filename">resolv.conf</tt><br/> </td><td align="left" valign="middle">Order in which to contact DNS servers (Domain Name Servers only).<br/> </td></tr><tr><td align="left" valign="middle"><br/> <tt class="filename">sendmail.cf</tt><br/> </td><td align="left" valign="middle">Main config file for the Sendmail server.<br/> </td></tr><tr><td align="left" valign="middle"><br/> <tt class="filename">services</tt><br/> </td><td align="left" valign="middle">Connections accepted by this machine (open ports).<br/> </td></tr><tr><td align="left" valign="middle"><br/> <tt class="filename">sndconfig</tt> or <tt class="filename">sound</tt><br/> </td><td align="left" valign="middle">Configuration of the sound card and sound events.<br/> </td></tr><tr><td align="left" valign="middle"><br/> <tt class="filename">ssh</tt><br/> </td><td align="left" valign="middle">Directory containing the config files for secure shell client and server.<br/> </td></tr><tr><td align="left" valign="middle"><br/> <tt class="filename">sysconfig</tt><br/> </td><td align="left" valign="middle">Directory containing the system configuration files: mouse, keyboard, network, desktop, system clock, power management etc. (specific to RedHat)<br/> </td></tr><tr><td align="left" valign="middle"><br/> <tt class="filename">X11</tt><br/> </td><td align="left" valign="middle">Settings for the graphical server, X. RedHat uses XFree, which is reflected in the name of the main configuration file, XFree86Config. Also contains the general directions for the window managers available on the system, for example <b class="command">gdm</b>, <b class="command">fvwm</b>, <b class="command">twm</b>, etc.<br/> </td></tr><tr><td align="left" valign="middle"><br/> <tt class="filename">xinetd.*</tt> or <tt class="filename">inetd.conf</tt><br/> </td><td align="left" valign="middle">Configuration files for Internet services that are run from the system's (extended) Internet services daemon (servers that don't run an independent daemon).</td></tr></tbody></table>

• Table 3-1. File types in a long list

  Symbol	Meaning
  -	Regular file
  d	Directory
  l	Link
  c	Special file
  s	Socket
  p	Named pipe
  b	Block device

• 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.

• Table 3-2. Subdirectories of the root directory

  Directory	Content
  /bin	Common programs, shared by the system, the system administrator and the users.
  /boot	The startup files and the kernel, vmlinuz. In some recent distributions also grub data. Grub is the GRand Unified Boot loader and is an attempt to get rid of the many different boot-loaders we know today.
  /dev	Contains references to all the CPU peripheral hardware, which are represented as files with special properties.
  /etc	Most important system configuration files are in /etc, this directory contains data similar to those in the Control Panel in Windows
  /home	Home directories of the common users.
  /initrd	(on some distributions) Information for booting. Do not remove!
  /lib	Library files, includes files for all kinds of programs needed by the system and the users.
  /lost+found	Every partition has a lost+found in its upper directory. Files that were saved during failures are here.
  /misc	For miscellaneous purposes.
  /mnt	Standard mount point for external file systems, e.g. a CD-ROM or a digital camera.
  /net	Standard mount point for entire remote file systems
  /opt	Typically contains extra and third party software.
  /proc	A virtual file system containing information about system resources. More information about the meaning of the files in proc is obtained by entering the command man proc in a terminal window. The file proc.txt discusses the virtual file system in detail.
  /root	The administrative user's home directory. Mind the difference between /, the root directory and /root, the home directory of the root user.
  /sbin	Programs for use by the system and the system administrator.
  /tmp	Temporary space for use by the system, cleaned upon reboot, so don't use this for saving any work!
  /usr	Programs, libraries, documentation etc. for all user-related programs.
  /var	Storage for all variable files and temporary files created by users, such as log files, the mail queue, the print spooler area, space for temporary storage of files downloaded from the Internet, or to keep an image of a CD before burning it.

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