Filesystem

• /bin - This is where basic Linux commands reside (ls, du, dd, cp, etc).
• /boot - Your boot images are stored here.
• /dev - Links to access your machine's devices.
• /etc - Configuration files and boot scripts.
• /home - User directories, equivalent to "Documents and Settings" in Windows XP.
• /lib - System libraries, codecs, etc.. similar to Windows/System and Windows/System32.
• /mnt, /media - Mount points. A mount point is a directory that the contents of your hard drives, cd/dvd drives, floppy drives, or jump drives will be accessible.
• /opt - Optional packages and programs. Could be thought of as a "Program Files" directory.
• /proc - Special dynamic information about your system.
• /root - System administrator home. Could be thought of as a "Documents and Settings/Administrator" directory.
• /sbin - Super-user binaries. These programs need super-user (root) privileges to execute.
• /tmp - Temporary files. Every user usually has read, write, and execute permissions here.
• /usr - The main place for programs to be installed. Most like "Program Files" in Windows.
• /var - System logs, mail spools, default web server directory, databases, etc...

Basic Commands

• cd - Change Directory: moves to a different directory.

  Usage: cd directory, cd .., cd /directory

• cp - CoPy: Copy a file or directory. If you wish to copy recursively and retain all attributes associated with the file or directory, use the -a option.

  Usage: cp original original.backup, cp -a /home/user/directory /home/user/backup

• df - Disk usage on Filesystem: Display an overall summary of disk usage on mounted mountpoints. If you want human-readable sizes, use the -h option.

  Usage: df, df -h, df /mnt/mountpoint

• du - Disk Usage: Display the disk usage of each file (recursively, by default) in the current directory. If you want human-readable sizes (1024 bytes = 1Kb, 1024Kb = 1Mb, etc), use the -h option. If you want a summary of the total disk usage by a directory and everything inside, use the -s option.

  Usage: du, du -s, du -h, du -sh, du -s /directory

• ln - LiNk: Create a link, or shortcut, to a file or directory. I prefer to do symlinks by using the -s option.

  Usage: ln original link, ln original /directory, ln original /directory/link, ln -s original /directory/link

• ls - LiSt: lists the contents of a directory.

  Usage: ls, ls .., ls /directory/subdirectory

• man - View the MANual page for a program or other file. Probably the most useful program ever.

  Usage: man program, man xorg.conf

• mkdir - MaKe DIRectory: create a new directory/folder.

  Usage: mkdir dirname, mkdir /directory/newdirname

• mv - MoVe: Move a file or directory to a new location, or rename a file or directory.

  Usage: mv file /directory/newhome, mv file newfilename

• pwd - Print Working Directory: returns the full path of the directory in which you are working.

  Usage: pwd

• rm - ReMove: Remove a file or directory. If you want to get rid of a directory and all of its contents, use rm -R or rm -Rf for recursive deletion.

  Usage: rm filename, rm /directory/filename, rm -Rf /directory/dirname

• rmdir - ReMove DIRectory: remove a directory. The directory must be empty.

  Usage: rmdir dirname, rmdir /directory/dirname

• whereis - Determine where a certain file exists (if it's in your path)

  Usage: whereis filename

• whoami - Detemine which user you are currently logged in as

  Usage: whoami

Linux Permissions

Linux has a great permission scheme. Since its inception, three basic levels of security have existed: user, group, and everyone. A simple way to change the permissions on a file or directory is to use the chmod, or CHange MODe, command. Changes to the permissions can be either a symbolic representation or an octal number representing the bit pattern for the new permissions. I prefer the symbolic method, myself, but many others prefer to see the octal pattern.

When working with permissions in Linux, always remember the following orders: User, Group, All; Read, Write, Execute. Those are the orders you will put the permissions in. Let's say that we want to make a file readable and writable only to the owner, while no one else will even be able to read the file. Here are some examples:

NOTE: Commands that begin with $ are executed as a regular user. Commands that begin with # are executed by a superuser (root). These two symbols (when they are the very first character in the command) are not entered by the user.

Symbolic:

$ echo "Hi" >> testing
$ chmod a-rwx,u+rw testing

Octal:

$ echo "Hi" >> testing
$ chmod 600 testing

Let's now examine the commands individually.

$ echo "Hi" >> testing

This command will append "Hi" (without the quotes) to the end of the file called testing. The file will be created if it does not already exist, assuming that the user has write permissions in the current directory. If you didn't want to append, you could overwrite anything that may be in the file by using a single > rather than >>.

$ chmod a-rwx,u+rw testing

This command removes (the - in a-rwx) read (the r in a-rwx), write (the w in a-rwx), and execute (the x in a-rwx) permissions from all (the a in a-rwx) users on the file called testing. Next we add (the + in u+rw) permissions for the owner (the u in u+rw) of the file: read (the r in u+rw) and write (the w in u+rw) on the file called testing.

$ chmod 600 testing

This command sets the permissions for everyone in one shot. I think of the digits in binary:

• 1 = execute only;
• 2 = write only;
• 3 = write and execute, but no read;
• 4 = read, but no write or execute;
• 5 = read and execute, but no write;
• 6 = read and write, but no execute;
• 7 = read, write, and execute.

A digit is required for each level of permissions (user, group, and all). It is also possible to put another digit before the 3 levels of permissions, but to be honest, I don't know what significance it has. A little bit of testing has shown that it puts either an S or T in place of the execute permissions (depending on the digit).

A couple more things about chmod: Directories must also be executable in order to list the contents. chmod is very powerful. Finally, you can recursively apply permissions to directories and everything underneath with the -R option.

$ chmod -R a+rx /home/user/share

A couple of commands closely associated with chmod are chgrp (CHange GRouP) and chown (CHange OWNer).

chown will change the user ownership of files or directories. This can be done recursively with the -R option. It also has the capability to change the group ownership built into it. The syntax is: chown [options] user[:group] file1 [file...]

chgrp will change the group ownership of files or directories. You can do this recursively with the -R option. The syntax is: chgrp [options] groupname file1 [file...]

Cronjobs

Cronjobs are similar to scheduled tasks in the Windows world. Schedule tasks or cronjobs are simply programs that you want to run regularly, without having to type in the command every time you want it to run. Most distributions come with a cron daemon of some sort installed by default. Generally speaking, you can edit your cronjobs by typing crontab -e. This will bring up an editor like vi (it usually is vi by default) in which you edit your cronjob file. Each user can have their own cronjobs (unless it's been disabled by the administrator, I would assume). Here is an example of a cronjob entry:

47 * * * * /usr/bin/run-parts /etc/cron.hourly 1> /dev/null

You'll notice the 47 with four *'s after it. This is how the daemon knows when to execute a job. This is what each of the stars represent in their order:

1. Minute: 0-59
2. Hour: 0-23 (0 = midnight)
3. Day of month: 1-31
4. Month: 1-12
5. Day of week: 0-6 (0 = Sunday)

So the example above will run after 47 minutes every hour of every day of the month of every month. You can also do some fancy things like having a job run every 5 minutes, after 15 and 45 minutes, etc. Let's say that we want to grab our mail every 5 minutes. The cronjob entry would look something like:

*/5 * * * * /usr/bin/fetchmail

If we wanted to grab our mail every 2 hours but only on Mondays, we would use the following:

0 */2 * * 1 /usr/bin/fetchmail

To have a job run after 15 and 45 minutes, we could do this:

15,45 * * * * /usr/bin/fetchmail

Pretty nifty, eh?

Make

This fancy utility is usually the means used for compiling programs from source. The usual sequence of commands for compiling and installing a program from the source in Linux is as follows:

$ ./configure
$ make
# make install

Most packages will follow this convention, but some require special procedures. Sometimes you can even get away with skipping the make and jump straight from ./configure to make install. It is always a good idea to read the README and INSTALL files included in source packages. They will generally tell you about anything out of the ordinary when compiling the source. Obviously, there is a lot more to this utility, but I'm not the person to explain it to you.

Package Management

There are several different types of package managers. The most popular these days are .rpm (RedHat Package Manager) and .deb (Debian). There are some other kinds of packages, but they aren't as popular as RPM and DEB. Slackware uses a straight .tgz (gzipped tarball) as its package system. Frugalware uses .fpm, which are bzipped tarballs. In the end, packages are almost always gzipped or bzipped tarballs.

Each package system has its ups and downs. I've personally found RPM-based distributions to be overly slow, especially with the package management. DEB-based distributions seem to be a lot more speedy when put up against RPM-based distros. However, I have found Slackware's TGZ-based system the most efficient and the fastest. Both RPM's and DEB's have dependency checking. In other words, the package manager will attempt to locate all entities upon which a program may depend in order to function properly before installing or upgrading that program.

A lot of people claim that .tgz packages are inferior to RPM and DEB because of the lack of dependency checking. By default, Slackware does not have dependency checking, but if you know what you're doing, you can get your dependencies a lot easier than you can with RPM or DEB (in my opinion).

RPM packages usually seem quite large compared to other package systems like DEB and TGZ. As far as I have seen, TGZ packages are smaller than both RPM and DEB packages. Here are a few options to help you use the RPM and TGZ package managers. I am not sure on Debian packages, so I won't attempt that one:

• RPM:
  • rpm -q or rpm --query: look for a package on your system
  • rpm -i or rpm --install: install a new package on your system
  • rpm -U or rpm --upgrade: upgrade a package which is already installed on your system
  • rpm -e or rpm --erase: remove a package from your system
• TGZ:
  • pkgtool: a text-based package manager
  • installpkg: install a package onto your system
  • upgradepkg: upgrade a package which is currently installed on your system
  • removepkg: remove a package from your system

You can also get some other programs that are VERY useful for package management. I think the latest craze for RPM's is YUM. I have not had great luck with this utility, but a lot of people really like it. Debian packages have used apt-get for ages now. My favorite add-on for Slackware packages is called swaret. Other distributions use the pacman utility, which is very efficient. Each one of these applications has several options and operation procedures.

Secure Shell and Secure Copy

One of my favorite aspects of Linux and other UNIX-derived systems is their secure shell capability (which is usually installed by default). Secure shell, or SSH, is a way for users to log into a remote computer and work on the remote computer as though it were right in front of them. Granted, it's all text-based unless you have X11 forwarding setup properly on both machines. But the command line interface (CLI) is extremely powerful--you should not be afraid to learn and use it. If you need to SSH from a Windows machine, you can use PuTTY.

In order to ssh into another computer, you simply type:

$ ssh hostname

or use the computer's IP address:

$ ssh xxx.xxx.xxx.xxx

By default, ssh on Linux machines will use the username of the account that you are running ssh from. Sometimes you need to login as a different user than the one you're currently using. To do that, you use the -l (lowercase L) or make it look like an e-mail address:

$ ssh hostname -l differentuser
$ ssh differentuser@hostname

Once your ssh session begins with the remote host, you will be asked to enter the password associated with the account with which you are attempting to login. If you do a lot of ssh'ing between machines, typing in your password several times is not only annoying but it could also pose a security risk--some wandering eyes might be watching you each time you enter your password. A great way to get around this is to generate a public and private key for your account. Once you do this, you can use the private key file on the machine you're ssh'ing out of and the public key on the remote machine.

To generate a public/private key, you can use ssh-keygen:

$ ssh-keygen -t rsa

You will be asked to enter and verify a passphrase for your private key. If you were aiming to get around not typing in your password, just hit enter twice for this part. It's still not secure, but it is a lot less hassle if you're only working on machines that no one else has "access" to. Usually your keys will be stored in ~/.ssh/ (or your /home/username/.ssh/ directory: ~ refers to your /home/yourusername).

The next step is to create your identification:

$ cd ~/.ssh
$ echo "IdKey private_key_file" > identification

Now you have to copy your public key (usually the one that ends in .pub) to the remote host:

$ scp public_key_file.pub username@xxx.xxx.xxx.xxx:/home/username/.ssh

And finally you should add your public key to the list of authorized users on the remote host by adding a line like the following to the ~/.ssh/authorization file:

Key public_key_file.pub

At this point you should be able to log into your remote host without your password (assuming you skipped the passphrase part of the key generation above).

As for the secure copy utility, you can get an idea of how to use it from the scp command above. This program uses the SSH system to securely copy files between two computers. This is how I use the scp command:

$ scp [-r] user@remote:/path/to/remote/file /local/destination/path/
$ scp [-r] /path/to/local/file user@remote:/remote/destination/path/

If you have setup public key authorization, you will not have to enter your password each time you use scp. Otherwise, you are asked for a password each time you run scp.

Archiving and Backup

There are many different kinds of compression and archiving tools in Linux. The most common types are tarballs, gzipped, and bzipped files. Below is a list of purposes for each of the three and some of the options:

• tar - multiple files, little or no compression
  • c, --create - create a tarball
  • f, --file - specify the tarball's filename
  • x, --extract, --get - extract the contents of a tarball
  • j, --bzip2 - use bzip2 compression/decompression
  • v, --verbose - show verbose output
  • z, --gzip, --ungzip - use gzip compression/decompression
  • to create a tarball called filename.tar which contains all of the files in /dir/to/archive: $ tar cf filename.tar /dir/to/archive
  • to create a tarball called filename.tar.gz which contains all of the files in /dir/to/archive and gzip it: $ tar zcf filename.tar.gz /dir/to/archive
  • to create a tarball called filename.tar.bz2 which contains all of the files in /dir/to/archive and bzip it: $ tar jcf filename.tar.bz2 /dir/to/archive
  • to extract the contents of a tarball called filename.tar.gz to the current directory: $ tar zxf filename.tar.gz
  • to extract the contents of a tarball called filename.tar.bz2 to the current directory: $ tar jxf filename.tar.bz2
• gzip - single file compression
  • To gzip a file called filename to make it filename.gz: $ gzip filename
  • To gunzip a file called filename.gz to make it filename: $ gunzip filename.gz
• bzip2 - single file compression
  • To bzip a file called filename to make it filename.bz2: $ bzip2 filename
  • To bunzip a file called filename.bz2 to make it filename: $ bunzip2 filename.bz2

Install Ndiswrapper

First, make sure that you have ndiswrapper installed on your system. You can install it by entering YaST. In KDE, click the K menu (the little green chameleon in the bottom left), go to System > YaST (Administrator Settings). You will be asked to enter the root password, which you set during installation. Once you've done that, you will see the YaST Control Center, which is a very powerful set of tools and utilities that greatly ease the configuration and management of SLED. Click on the Software category on the left to show a list of software management options (if it's not already displayed). Click on the Software Management module.

Once loaded, you will see an interface which is very similar to what you would see during the expert package selection while installing SLED. Make sure your Filter (in the top left) is set to Search, and enter ndiswrapper in the search box. The search will return a few different results for ndiswrapper. The first result, ndiswrapper by itself, should be sufficient for most of us. When you check the box by ndiswrapper, you will see a warning informing you that ndiswrapper-based network are not officially supported by Novell. Just click OK to dismiss this warning.

Now you should be ready to install ndiswrapper. Click the Accept button in the bottom right. You will be asked to confirm the installation of ndiswrapper; click Continue. If your installation media is not still inserted, YaST will request the disc which contains the ndiswrapper packages. Insert the disc and click OK. In my case, two packages were installed. It may or may not differ for you.

As soon as the packages are done installing, your configuration settings are saved once again, and you will be asked if you want to install or remove more packages. Click No. At this point, ndiswrapper should be installed on your system, and you may dismiss the YaST Control Center.

Determine Your Wireless Adapter Make/Model

This step is absolutely necessary because if you install the wrong drivers, there is a chance (small as it may be) that your wireless adapter will be damaged. So let's ask Linux how our wireless adapter identifies itself. To do this, log into your SLED and open a Terminal or Konsole. On KDE, you can use the third button (a monitor with a black screen and > on it) on the menu panel at the bottom of the screen, or you can also click the "K" menu (same place as a regular start menu in Windows), go to System > Terminal > Konsole (Terminal Program). I am not exactly sure where this item is located with GNOME, but it might be under the System menu.

Once you have opened a terminal window of some sort, you must switch to a root user environment:

$ su -

You will then be asked for the root password, which you set during installation. Enter that password and type

# lspci

This command lists all of your PCI devices, according to the man pages, but you will see most if not all of your devices, PCI or otherwise, listed here. You'll notice that there is probably quite a list of devices. You may be interested in what your computer has in it, but since you're looking specifically for your wireless adapter, try one of the following commands

lspci | grep Broadcom
lspci | grep Wireless

The | after lspci will pipe the output of lspci to a useful and powerful program called grep. In this case, grep just looks for any lines that contain either the word Broadcom or Wireless. If you don't get any results from either of the two commands above, try to think of other keywords that might be used to identify a wireless adapter. My laptop returns the following:

# lspci | grep Broadcom
06:02.0 Network controller: Broadcom Corporation Dell Wireless 1470 DualBand WLAN (rev 02)

When you find the wireless adapter, pay attention to the numbers in front of it (06:02.0 on my laptop). With those numbers, you can get the information you need to find the right drivers for your particular wireless adapter. Enter the following command, substituting my device numbers with yours:

# lspci -n | grep 06:02.0
06:02.0 Class 0280: 14e4:4319 (rev 02)

This command gives you the wireless adapter's numeric ID; mine is 14e4:4319.

Download Your Device Drivers

Now that you know your device's numeric ID, you can go to the ndiswrapper wiki, which has a list of numeric IDs and the drivers that are known to work with that device. Look for your wireless adapter on the list of devices. I would recommend using your browser's search or find on page function to locate your device by the numeric ID that you just found.

I'll leave the retrieval of your device drivers up to you.

Install The Wireless Drivers

Most device drivers will come in an archive of some sort. Mine came in a RAR file. Extract your drivers to the directory of your choice--maybe something like ~/wireless. You can use the archive utility provided by SLED to extract your files. It functions very similar to WinZip, WinRAR, and other popular archive clients. By the way, the ~ in a directory listing refers to the current user's home directory (/home/user, for example).

Now, go back to the root terminal that you used to determine what kind of adapter you have. Navigate to the directory where you extracted your drivers and list the contents of the directory, looking for any *.inf files:

# cd ~/wireless
# ls

Ndiswrapper will use an INF file to know how it is supposed to install the driver. My INF file is called bcmwl5.inf. Now for the actual installation of the drivers:

# ndiswrapper -i bcmwl5.inf
Installing bcmwl5
Forcing parameter IBSSGMode|0 to IBSSGMode|2

Now check to make sure that the driver is there and that it recognizes your hardware:

# ndiswrapper -l
Installed drivers:
nbcmwl5          driver installed

Ooops!!! It doesn't recognize that my hardware is actually there. If you see 'driver installed, hardware present' then you should be good to go. You may proceed to the next step. However, if you have the same problem as me, you either have the wrong drivers or ndiswrapper installed the drivers improperly. This problem took forever to track down when I was first trying to get my wireless to work. Remember the numeric ID that you found earlier? Check this out:

# cd /etc/ndiswrapper/bcmwl5
# ls
14E4:4318.5.conf  bcmwl5.inf  bcmwl564.sys

Wait a second! Remember how my numeric ID was 14E4:4319? Why is there a listing for 14E4:4318.5? To solve this problem, I am just going to make a symlink (a shortcut) to 14E4:4318.5.conf and call it 14E4:4319.5.conf:

# ln -s 14E4:4318.5.conf 14E4:4319.5.conf

Now when I run the command to see if my hardware is recognized, I get this:

# ndiswrapper -l
Installed drivers:
bcmwl5          driver installed, hardware present

Hurray!! It says 'hardware present' in there!!! That means that the drivers are working and that my device can be used!

Enable Your Wireless Device

With ndiswrapper recognizing your wireless adapter, you can now enable it and start wirelessing your life away:

# modprobe ndiswrapper

There have been times when this particular step will lock up my machine and I have to do a hard reset, but most times it will work fine.

Connect to a Wireless Network

This part also gave me issues for a long time when I first installed my wireless drivers on SuSE Linux 10.1. I was able to connect to the wireless access points provided by my apartment complex, but I could not for the life of me connect to my own wireless router. Hopefully you don't encounter the same problem.

To see what access points you have available to you, check out the KNetworkManager applet in your system tray (next to the clock). I have 7 possible access points listed in the menu, including my encrypted router. When I clicked on my network, it asked me for my passphrase and connected immediately. Nice! That's definitely one plus for SLED over SuSE Linux 10.1!!

I am actually amazed at how easy it was to get my wireless working the second time around. Hopefully your wireless adapter installation was as painless as mine with the help of this guide.

BACKUP ALL IMPORTANT DATA BEFORE PROCEEDING

We all hate losing the projects that we've slaved over for weeks and months. Take the proper precautions to backup anything you wouldn't like to lose before installing any flavor of Linux. That's not to say that you will lose everything, but it's not unheard of to wipe out all data from your drive while attempting to install Linux. With that warning out of the way, let's get started!!!

The Initial Boot And Final Settings

When we boot up our SLED for the first time after installation, we are asked to provide a hostname to identify our machine on the network. When you have set the hostname and domain name as you want them, click next. Now we're asked to set the root password. Make sure this password is one that you'll not forget, but at the same time make sure that it's not easy to guess. If someone gets root access to your machine, there's no end to what they can do.

First Login

When you see this login screen, enter the username and password that you created for the unprivileged user. You'll see a fancy loading screen while your profile is being created for the first time.

Now, you may or may not have noticed, but I wrote this article as I installed SLED. I want to watch a movie now, so subsequent configuration (wireless, 3D acceleration, etc) will take place later. I hope this is good enough for the time being.

Install Subversion

If you haven't already installed subversion, you can download it from http://subversion.tigris.org/. You can download the svn package for a variety of platforms. If you download the source package, you should simply have to do the following as root:

• unpack the archive and enter that folder
• configure the application for your system by typing ./configure on the command line
• compile the source code by typing make
• install the package by typing make install

Note: these are the general steps for installing a package from the source; they may be slightly different with svn.

Choose A Home For The Repository

Next, choose a place for your server to keep track of all of the changes to your project. Try a place like /var/svn or /home/[your_username]/svn. I would recommend creating a folder specifically for the repository.

Create The Repository

Once you're in the directory in which you wish for your svn repository to reside, type the command svnadmin create repo or you can type the full path to be certain svnadmin create /var/svn/repo. This will create the repository.

Import Your Project

I do most of my development on my local area network, so I haven't created a repository that can be used over the Internet. I would imagine that it's pretty similar to what we do to create a repository for your LAN. Choose a project to import into your repository and navigate to the folder that the project is in. For example, if I have a project called Foo in /var/www/htdocs/foo, I would go to /var/www/htdocs. Next, use the command svn import to pull your project into the repository. For our Foo project, we would use the command svn import foo svn://localhost/var/svn/repo/foo -m "Initial Import". This will create a new folder in our repository at /var/svn/repo called foo (/var/svn/repo/foo). Our project files will put crammed into that directory for tracking.

Checkout Your Project

In order to be able to save your changes to our repository, we have to checkout the project again from the server. This is a pretty simple step, but it is critical. Even though we imported our project already, that folder remains untouched. SVN will not know how to handle the updates unless we checkout the project from the svn server. So, we proceed to checkout by removing or renaming /var/www/htdocs/foo and typing svn checkout svn://localhost/var/svn/repo/foo /var/www/htdocs/foo. This will place some hidden folders in each of the directories in your project. These hidden folders keep track of your local changes so that svn will know how to merge your changes with those of other developers.

Update The Repository

When you've made some changes that you want to save, you can send them out by typing svn commit /var/www/htdocs/foo. This command knows how to get to the server to save the changes, since the project was checked out from the repository.

Update Your Files

Sometimes you'll need to get changes that other developers have made, or revert back to a version of your project that didn't have as many problems. You can do this using the svn update command. If you're already in /var/www/htdocs/foo, you can type svn update and it will update files that have been changed in the repository since you last updated. If you're looking to get an older version of your project, you can type svn update -r PREV or a revision number in place of PREV.

Remember, these are just the basics of using SVN. You can do many amazing things with this utility. I actually did all of this as I was writing this article, so I'm sure that it works.