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Linux Tips and Tricks

Tip 1: Which distribution is good for youThey are all good. But that's not a real tip. What you should be looking for is which distribution you feel the most comfortable with. RedHat has the reputation of being very easy to install. They provide special tools to make the configuration easier. Debian also has some tools, but will usually require you to go on the command line more often to configure the system. If you want to be on your own, and really learn how to edit configuration files then Slackware is for you. The Web site http://www.linux.org lists all the available distributions. In the end, the best person to decide which distribution you like, is yourself.
Tip 2: How to find a Linux CD-ROM at low costThe Linux market started from a few distributions available only from FTP servers, to full feature commercial distributions available in stores and online including a printed manual and phone support. Here are the main choices you have when looking for a Linux distribution: • You can download any Linux distribution from its FTP server. To take a few examples, RedHat can be downloaded from ftp://ftp.redhat.com, Slackware from ftp://ftp.cdrom.com and Debian from ftp://ftp.debian.org. That method is free, but requires you to have a fast Internet connection. Downloading a full Linux distribution over a 56Kbps modem will take you quite a few hours. An other way is to buy a full distribution. RedHat, for example, can be bought online for about $50. This will include a box, a CD-ROM, a boot diskette, a manual and support from RedHat. The last way is to buy only the CD-ROM. There are a few places selling CD-ROMs of various distributions for $2. One of them is http://www.cheapbytes.com. You will only get the CD-ROM, but this is all you need to install Linux if you are comfortable with the fact that you don't get a printed manual or free support. You can find the manual and other documentation on the CD-ROM.
Tip 3: Multiple operating systemsA computer only needs one operating system to work. But what if you just want to try out a new system? Do you need to forget about the old one and erase your hard drive? No, you can have as many operating systems on your computer as you wish. Linux requires 2 partitions to work. Partitions are sections of the hard drive. When you install Linux, it will provide a program called fdisk or disk druid allowing you to create the needed partitions. The main problems people have is that they don't have empty partitions to use for Linux, and they don't want to erase the current Windows or DOS partition. The trick is to resize your current partition to create empty space. Then you will be able to make the partitions needed by Linux to install properly. Fdisk doesn't allow you to resize a partition. You will need to use another program to do the job, before using fdisk to create the Linux partitions. A very popular commercial product to do this is Partition Magic from http://www.powerquest.com. Let's see step by step what is needed to resize an existing partition to allow the creation of a new one for Linux: • • • • • Buy Partition Magic, or get any other tool that can safely resize partitions. Make sure you have at least 150 megs free on your main partition, the required amount for Linux. Resize the partitions so you have at least 150 megs free, outside of any current partition. Reboot and launch the Linux installation. Run fdisk or any partitioning program that comes with the Linux distribution, and follow the installation instructions to make the required Linux partitions. 7
Tip 4: Installing with no CD-ROM drive or modemMost Linux distributions come on a CD-ROM. You can also download them from an FTP site, but that requires an Internet connection. What if you have a system with no CD-ROM drive or Internet connection, like an old 486 laptop? The trick here is to have another desktop system with a CD-ROM drive, and a null-modem serial cable. I will show you how to do it with Slackware. It is also possible with most other Linux distributions. Insert the Linux CD-ROM in the drive on the desktop and copy the A (base) and N (networking) packages on diskettes. You need at least those in order to use a serial cable to transfer the rest of the packages. Now you need to enable NFS networking on the desktop, and allow the laptop to connect. You can give a temporary IP address to the laptop, like 192.168.1.11 that you need to add to your /etc/exports file on your desktop. To link the two systems together, this is what you need to type on the laptop:/usr/sbin/pppd -detach crtscts lock 192.168.1.11:192.168.1.10 /dev/ttyS1 115200 And this on the PC:/usr/sbin/pppd -detach crtscts lock 192.168.1.10:192.168.1.11 /dev/ttyS1 115200 This is assuming the cable is linked to ttyS1 (COM2) on both systems. With NFS, you can mount the CD-ROM drive remotely and tell the installation program to use a specific path to install the remaining packages. Mount the CD-ROM with a command like this:mount -tnfs 192.168.1.10:/cdrom /mnt Then run the installation program:setup and enter the new path for the packages files.
Tip 5: Swap and memoryOne important setting in any protected mode operating system like Linux is the swap space. In the installation, you will need to create a swap partition. A common question is what size should the partition be? The proper size depends on 2 things: The size of your hard drive and the size of your RAM memory. The less RAM you have, the more swap you will need. Usually you will want to set your swap space size to be twice the RAM size, with a maximum of 128 megs. This of course requires you to have a hard drive with enough free space to create such a partition. If you have 16 megs of RAM, making the swap space 32 megs or even 64 megs is very important. You will need it. If you have 128 megs of RAM on the other hand, you won't need much swap because the system will already have 128 megs to fill before using swap space. So a swap partition of 128 megs or even 32 megs could be enough. If you don't select enough swap, you may add more later.
Tip 6: More swap with a swap fileYou installed a new Linux system, but forgot to set enough swap space for your needs. Do you need to repartition and reinstall? No, the swap utilities on Linux allow you to make a real file and use it as swap space. The trick is to make a file and then tell the swapon program to use it. Here's how to create, for example, a 64 megs swap file on your root partition (of course make sure you have at least 64 megs free):dd if=/dev/zero of=/swapfile bs=1024 count=65536 This will make a 64 megs (about 67 millions bytes) file on your hard drive. You now need to initialize it:mkswap /swapfile 65536 sync And you can then add it to your swap pool:swapon /swapfile With that you have 64 megs of swap added. Don't forget to add the swapon command to your startup files so the command will be repeated at each reboot.
Tip 7: Kernel size and modulesTo configure Linux to detect a new hardware part, especially on a new kernel, you may need to recompile the kernel. If you add too many devices in the kernel configuration, you may get an error message telling you that the kernel is too big. The trick is to enable modules. The kernel itself must be a certain size because it needs to be loaded in a fixed memory size. This is one reason why modules can be very handy. If you enable modules, you will need to make them:make modules and install them:make modules_install Then using the modprobe utility you can load selected modules on bootup. This way the kernel will be smaller and will compile with no error.
Tip 8: The boot promptThe Linux system uses a program called LILO to boot itself. This is the LInux LOader, and will load a kernel and can pass various parameters. This is what the "boot:" prompt is for. At the "boot:" prompt, you can enter a lot of parameters. You can send parameters to drivers like the ethernet driver, telling it at which IRQ the ethernet card is located, or you can pass parameters to the kernel, like memory size or what to do in a panic. Reading the LILO manual will tell you all of the nice things LILO can be used for. Note that for device drivers compiled as modules, you need to pass values when you load these drivers, and not on the "boot:" prompt.
Tip 9: Wrong memory size foundThe Linux kernel will detect various settings from your computer configuration. This includes the size of memory you have. In some cases, it will find the wrong size. For example, it could find only 64 megs of memory when in fact you have 128 megs. The trick here is to specify the amount of RAM memory you have with the "mem=" parameter. Here is what you would type when your system boots if you have 128 megs of memory:LILO boot: linux mem=128M This will tell LILO to load the linux kernel with 128 megs of memory.
Tip 10: Master boot record and LILOWhat is the master boot record (MBR) and why does LILO erase the old boot loader? Every hard drive has a top space called the MBR where the BIOS will try to load an operating system. Every system has its own loader. DOS has DOS-MBR, Windows NT has the NTLDR and Linux has LILO. When you install LILO, you can install it in the MBR or in a boot record for the Linux partition. If you want to keep your current boot loader, you can select the Linux partition, and make sure it is the active partition in fdisk. This way you will be able to boot to LILO, and then boot the old loader from the MBR. If you plan on only using Linux on your system, you can tell LILO to boot right into Linux and not display a "boot:" prompt, and you can install it in the MBR.
Tip 11: LILO can't find a kernel on a big driveOn some big hard drives, LILO can have problems loading your kernel. The problem is because the hard drive has more then 1024 cylinders. The trick is to make sure your kernel is in the first 1024 cylinders so LILO can find it. The way to do this is to make a small /boot partition at the begining of the drive, and make sure the kernel is in the /boot directory. You can set the partitions in fdisk, and select the right path for the kernel in /etc/lilo.conf so LILO knows where it is. When you compile your kernel, simply move the new kernel in that directory so LILO can load it.
Tip 12: X Window configuration optionsEach Linux distribution has its own X Window configuration program. XFree86 also has a text-based configuration program which is complex to use. But what if both the distribution program and xf86config, the text-based configuration for XFree86, do not seem to do what you need? XFree86 also comes with a graphical configuration tool. The name of the graphical program is XF86Setup. This will launch a graphical window and allow you to configure the X Window Server. So if you don't like the console configuration programs, you can use this one:

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