Debian basic features
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- Chris Lale
- chrislale AT users DOT berlios DOT de
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Revision History
Revision 1.0 | 11th September 2005 | Revised by Chris Lale | ||||||||||
Initial release | ||||||||||||
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Revision 1.1 | 7th January 2006 | Revised by Chris Lale | ||||||||||
Modified for NewbieDOC. Changed title from 'What you might like to know before you install Debian GNU/Linux'. | ||||||||||||
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Revision 1.2 | 22nd November 2007 | Revised by Chris Lale | ||||||||||
Modified so that a stable version can be included in the "newbiedoc" package. | ||||||||||||
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Revision 1.3 | 25th September 2009 | Revised by Chris Lale | ||||||||||
Updated and checked as being compatible with Debian Squeeze. | ||||||||||||
This article describes some of the basic features of Debian GNU/Linux. These are the sort of things that you might like to know about before you install Debian on your computer.
1 What Debian isDebian GNU/Linux is a free operating system. The engine of an operating system is called the kernel. Debian uses the Linux kernel. The rest of the operating system that lets you use the kernel consists of a number of tools. In Debian, these are provided by the GNU project. You can install Debian as a replacement for Windows or as part of a dual-boot system. For more detail see http://www.debian.org/intro/about. 2 Linux filesystemWindows has a directory tree for each drive. Each tree begins with a drive letter. Linux has only one tree called the filesystem. It starts with the symbol for the root directory: '/'. (There is a special user also called root. User root's home directory is '
In Linux, the user never needs to know which physical drive contains particular data. This is unlike Windows where you need to know which drive (C:, D:, etc) to use. Instead, in Linux you mount a drive to a particular mountpoint in the directory tree. For instance, the first CD drive in Windows might be D: or E: or some other drive letter and might change if other drives are added to or removed from the system. In Linux, the mountpoint for the first CD drive is If you install an application in Windows, the executable and related files are normally installed to
Linux does not have a registry. Configuration data is normally in the form of text files installed in 3 Disc devices and partitionsIn Windows, the active primary partition on the primary master IDE disc is called C:. Other partitions (and CDROM drives) are called D:, E: etc. In Windows 98 and earlier, the allocation of drive letters to partitions is automatic and fixed. From Windows NT onwards it is possible to reassign some drive letters. In Linux, it is often said that "everything is a file". In the case of discs, the whole primary IDE master disc is the device The first SCSI hard disc is PATA drives (connected with flat cables) are treated as IDE ATA drives ( It is possible to have up to 4 primary partitions on a hard disc. One of them can be an extended partition containing up to 63 other logical partitions. The logical partitions must be contiguous. Windows uses only one primary partition and one extended partition containing logical partitions. Linux can use all the partitions, but manual configuration is needed to use more than 20 partitions per disc in Debian. If CD or DVD drives cannot be partitioned. A typical CD drive would be In Windows, there may be two floppy drives, A: and B:. In Linux, the floppy drives are 4 Mounting and unmounting devicesEverything in Linux is a file - including devices such as disc drives. In order to use a drive, you must mount the device to a mountpoint in the filesystem. You can then access the drive from the mountpoint. For example, you may wish to use another hard drive to store backups of your system. To add manually an EXT3 formatted partition $ mount -t ext3 /dev/hdb1 /mnt/backup and unmount it with the $ umount /mnt/backup or $ umount /dev/hdb1 The configuration file Removable media can be automatically mounted if you install an automounter. The X-window desktop Gnome includes automounting as standard. The media will not unmount or eject until all processes involving it are finished. In Gnome, right-click on the CD icon and choose eject. 5 Filesystem formatsThe most common Linux format is EXT2 (the Second Extended file system format). Recent distributions use EXT3 which is EXT2 with a journaling system. The journal protects against corruption of filesystem data which might cause lost files etc. As well as being robust, EXT2/3 partitions are efficient and do not need to be defragmented. They can be checked and repaired with the filesystem checker Windows cannot access native Linux formatted drives, but Linux can read from and write to other formats such as FAT, FAT32, etc. However, writing to NTFS is not recommended (see http://linux-ntfs.sourceforge.net/info/ntfs.html.html#3.2). 6 Linux malwareThere has not been a real Linux virus epidemic in the wild. This is because a virus (or any other program) can only carry out actions that the user running the virus is allowed to do. Normal users do not have enough privileges to cause damage to the system. Only user root can do that. You would have to run an untrusted binary as root to run any risk. Desktop users routinely do not log in as root, and only switch user to root to run specific, trusted software. You have to deliberately try to circumvent this protection and know the root password to be at risk. Worms exploit known security holes. Generally, there are very few new or unknown holes. Defeating worms and trojans is as easy as keeping software up to date. There are Anti-Virus scanners available for Linux (but generally speaking no Linux viruses). However, they will pick up Windows viruses and stop you spreading them to Windows users. 7 Linux securityThe most important practice is never to login as user root (the superuser). Only user root has access to everything - that is why you must be root during the installation process. Always login as a normal user (low privileged user). If you need root privileges for an application, switch user to root as follows:
Debian is installed with security features enabled by default. You can disable features that you do not need, but you are unlikely to do this unless you know what you are doing. This approach means that you are unlikely to make yourself vulnerable through ignorance or accident. For a computer connected to the internet, keeping the system constantly up to date means that security holes are plugged almost as soon as they are discovered. You need this line (uncommented ie without a preceding deb http://security.debian.org/ etch/updates main contrib non-free 8 Linux bugsAnyone finding a bug in Debian can report it using the bug tracking system. Most of the bugs are sorted out before the software moves into the stable distribution ( ie in the testing or unstable distributions). See http://www.debian.org/Bugs/. 9 Running Windows applicationsThere is free Wine which works by making systmem calls directly to Linux (Wine Is Not an Emulator). A commercial version called Crossover Office is very stable for apps like MS Office (see http://www.codeweavers.com/products/cxoffice/). There is also a commercial version for Windows games called cedega (http://www.transgaming.com/). Alternatively, if you have a copy of Windows, you can set up a virtual machine running within Debian. You can use a Debian package such as virtualbox or qemu. There are commercial emulators such as Vmware. 10 Installing softwareThe traditional way of installing Linux software is by compiling the binary (executable file) on your own computer from source code. This is actually quite easy and is one of the reasons why viruses are not a problem in Linux - they normally hide in pre-compiled binaries but are obvious foreigners in source code. The drawback for the novice user is that Linux is modular and an application may depend on one or more other applications, which in turn may depend on other applications, etc. So you may find that compilation fails because you have not installed all the necessary depenedencies. This is solved by Debian's packaging system Apt (Red Hat Linux has an alternative packaging system called Rpm). In Debian, the application is pre-compiled for your computer's architechture and packaged together with associated files, configuration data, etc in a single 11 Help and supportMost problems can be solved by reading the documentation:
If the problem persists read http://www.catb.org/~esr/faqs/smart-questions.html and ask at
12 Bibliographyhttp://www.pathname.com/fhs/ Linux Filesystem Hierarchy Standard http://www.pathname.com/fhs/ Comparison of Windows and Linux drives and partitions http://linux.org.mt/article/partnames?locale=mt Linux device names for IDE and SCSI http://www.tldp.org/HOWTO/Partition/partition-2.html Viruses, security etc http://www.patentmatics.org/pub2002/pub121.htm http://www.dwheeler.com/oss_fs_why.pdf http://www.seifried.org/security/index.php/Linux_and_Viruses http://www.theregister.co.uk/security/security_report_windows_vs_linux/ http://www.debian.org/security/ 13 Appendix A: LicenceCopyright (c) 2005-2009 Chris Lale. chrislale AT users DOT berlios DOT de
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