Linux Features


1)multitasking: several programs running at the same time is called multitasking.

2)multiuser: several users on the same machine at the same time through different terminals/from remote hosts.

3)multiplatform: runs on many different CPUs, not just Intel like AMD too.

4)multiprocessor: SMP(Symetri multi processing) support is available on the Intel and SPARC platforms (with work currently in progress on other platforms), and Linux is used in several loosely-coupled MP applications.

5)multithreading: has native kernel support for multiple independent threads of control within a single process memory space.

6)runs in protected mode on the 386. ie Protected mode has a number of new features designed to enhance multitasking and system stability, such as memory protection, and hardware support for virtual memory as well as task switching It is sometimes abbreviated p-mode and also called Protected Virtual Address Mode

7)has memory protection between processes, so that one program can't bring the whole system down.

8)demand loads executables: Linux only reads from disk those parts of a program that are actually used.

9)shared copy-on-write pages among executables. This means that multiple process can use the same memory to run in. When one tries to write to that memory, that page (4KB piece of memory) is copied somewhere else. Copy-on-write has two benefits: increasing speed and decreasing memory use.

10)virtual memory using paging (not swapping whole processes) to disk: to a separate partition or a file in the filesystem, or both, with the possibility of adding more swapping areas during runtime (yes, they're still called swapping areas). A total of 16 of these 128 MB (2GB in recent kernels) swapping areas can be used at the same time, for a theoretical total of 2 GB of useable swap space. It is simple to increase this if necessary, by changing a few lines of source code.

11)a unified memory pool for user programs and disk cache, so that all free memory can be used for caching, and the cache can be reduced when running large programs.

12)mostly compatible with POSIX, System V, and BSD at the source level.

13)POSIX job control.

14)pseudoterminals (pty's).

15)multiple virtual consoles: several independent login sessions through the console, you switch by pressing a hot-key combination (not dependent on video hardware). These are dynamically allocated; you can use up to 64.

16)Supports several common filesystems, including minix, Xenix, and all the common system V filesystems, and has an advanced filesystem of its own, which offers filesystems of up to 4 TB, and names up to 255 characters long.

17)transparent access to MS-DOS partitions (or OS/2 FAT partitions) via a special filesystem: you don't need any special commands to use the MS-DOS partition, it looks just like a normal Unix filesystem (except for funny restrictions on filenames, permissions, and so on). MS-DOS 6 compressed partitions do not work at this time without a patch (dmsdosfs). VFAT (WNT, Windows 95) support and FAT-32 is available in Linux 2.0

18)special filesystem called UMSDOS which allows Linux to be installed on a DOS filesystem.

19)read-only HPFS-2 support for OS/2 2.1

20)HFS (Macintosh) file system support is available separately as a module.

21)CD-ROM filesystem which reads all standard formats of CD-ROMs.

22)TCP/IP networking, including ftp, telnet, NFS, etc.

23)Lan Manager/Windows Native (SMB) client and server

24)Linux is free, in two senses. First, you may pay nothing to obtain and use Linux. On the other hand, you may choose to purchase Linux from a vendor who bundles Linux with special documentation or applications, or who provides technical support. However, even in this case, the cost of Linux is likely to be a fraction of what you'd pay for another operating system. So, Linux is free or nearly free in an economic sense.
Second, and more important, Linux and many Linux applications are distributed in source form. This makes it possible for you and others to modify or improve them. You're not free to do this with most operating systems, which are distributed in binary form. For example, you can't make changes to Microsoft Windows or Microsoft Word - only Microsoft can do that. Because of this freedom, Linux is being constantly improved and updated, far outpacing the rate of progress of any other operating system. For example, Linux will likely be the first operating system to support Intel's forthcoming Merced 64-bit CPU.

25)Linux has attractive features and performance. Free access to Linux source code lets programmers around the world implement new features, and tweak Linux to improve its performance and reliability. The best of these features and tweaks are incorporated in the standard Linux kernel or made available as kernel patches or applications. Not even Microsoft can mobilize and support a software development team as large and dedicated as the volunteer Linux software development team, which numbers in the hundreds of thousands, including programmers, code reviewers, and testers.

Table 1: Sales of Popular Desktop Operating Systems
Operating System
Windows 95/98
Windows NT Workstation
DOS with Windows 3.x
DOS without Windows
OS/2 Warp

Table 2: The History of Linux
Kernel size (Bytes)
Linus Torvalds writes Linux kernel
GNU software integrated with Linux kernel, producing a fully functional operating system
High rate of code contributions prompts Linus to delegate code review responsibility
First production release
Linux adapted to non-Intel processors
Linux supports multiple processors, IP masquerading, and Java
Linux growth rate exceeds that of Microsoft Windows NT

Table 3: Popular Linux Distributions and Their Web Home Pages
Home Page
Caldera OpenLinux
Debian Linux
Slackware Linux
Red Hat Linux
SuSE. Linux

Table 4: Recommend Linux Web Pages
Web page
Debian Project Web Page
Eric S. Raymond's Linux Reading List HOWTO
Gary Singleton's Gary's Place: Linux News Tips and Links
Joshua Go's Linux Guide
Linux Documentation Project
Linux Journal Web Page
Linux Journal's Linux Gazette
Linux Resources
Linux Web Ring
Linux Weekly News
O'Reilly & Associates Linux Center
Renaissoft's Linux Resources
Robert Kiesling's Linux Frequently Asked Questions with Answers (FAQ)
Victoria, British Columbia Linux Users Group

Some addtionoal info:

link1: a debat on wether to chose linux or not must read it

again some fun time now

My linux faverate site's regarding linux


1) As i told that linux supports different platforms what are they?
A) Intel X86, Intel Itanium, AMD AMD64 , IBM zSeries, iSeries, pSeries, S/390,notbook systems, and PDA's etc

2) what is simetric multi processing(SMP)?
A.Symmetrical Multi Processing. A computer hardware architecture which distributes the computing load over a small number of identical processors, which share memory. Very common in Unix and Windows NT/2000 systems.

3)what is pre-emptive multi tasking?
Pre-emption as used with respect to OS means the ability of the operating system to preempt or stop a currently scheduled task in favour of a higher priority task. The scheduling may be one of, but not limited to, Process or I/O scheduling, among others.

4) then my quation is what is non-preemptive multitasking?
A. Any form of multitasking where the OS cannnot preempt a running task and process the next task in the queue(i think now u got the definition)

Why “Free Software” is better than “Open Source”
A. no explination to this from me but i can give a link u can read it

6)what are diffrent file system's in linux?
A.1).minix 2)nfs, 3)ext, 4)
ext2, 5)ext, 6)vfat, 7)msdos, 8)fat, 9)nls, 10)smbfs, 11)autofs,12)cramfs, 13)nfsd, 14)ufs, 15)ramfs, 16)romfs 

17)autofs4 18)
reiserfs 19) coda 20) ncpfs 21)umsdos 22)sysv 23) udf 24) hfs 25) freevxfs 26) bfs 27) hpfs 28) cmsfs 
29) affs 30)
isofs (i told u linux by default can understand iso files) 31)adfs 32) xfs 33) proc(noting but linux virtual file system) 34) 

so now its ur duty to check the above file system details in

and one more thing the red indicate importat file system's ok?

7then my quation is what is actually a file systyem?
In computing, a file system is a method for storing and organizing computer files and the data they contain to make it easy to find and access them. File systems may use a storage device such as a hard disk or CD-ROM and involve maintaining the physical location of the files, or they may be virtual and exist only as an access method for virtual data or for data over a network (e.g. NFS)

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  • Swap Management - II


    Advanced Swap management
    Actually its advantageous if we create swap partition separately if the server is not having any raw space left what we can do ? At any cost we have to increase the swap to improve the system productivity 
    To come out of this situation there is one solution provided by Linux e.i we can create a swap file with in all ready existing and using partition if that partition is having sufficient free space

    Step1:Switch off all the swap before any swap management

    #swapoff -a

    Step2:Determine what is the swap size we required(here i am taking 128MB) and execut the following command with count equal to 131072 (because 131072 is equal to 128M)

    #dd if=/dev/zero of=/swapfile bs=1024 count=131072

    Step3:Now set this swap file in order to use this file as swap

    #mkswap /swapfile

    Step4:Edit the /etc/fstab file to specify the swap file for perminient swap space

    #vi /etc/fstab

    /swapfile    swap    defaults    0 0


    Step5:Update the kernel about the mount table changes

    #mount -a

    Step6:After managing the swap on the swap

    #swapon -a

    Step6:Check weather the swap space is updated or not by using following commands

    #free -m   
    #swapon -s 
    #cat /proc/swaps

    Removing swap:

    Step1:Before doing any thing with swap first we have to switch of the swap

    #swapoff -v /swapfile

    Step2:Remove/comment the entry of swap from /etc/fstab file

    #vi /etc/fstab

    then save and exit

    Step3:update the kernel about mount table changes

    #mount -a

    Step4:Remove the swapfile permanently 

    #rm /swapfile

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  • Swap management


    Swap management - I
    Step1:First check what is the swap space the system is having and utilization of swap size

    #free -m   
    #swapon -s 
    -s for st
    #cat /proc/swaps

    this will give output of swap statistics in Megabytes(m), if we want the output in Kilobytes then free -k

    Step2:Before starting the Swap management we have to take precautions such as switch off all the swap and no user should be logged in  

    #swapoff -a

    Step3:Check in the system if there is any raw space in the system

    #fdisk -l

    Step4:If the system is having free space then create a partition which support swap(partition type 82) with required amount of free space

    #fdisk /dev/hda

    p                #press p to print the partition table
    n                #press n for creating new partition
    256M          #specify the amount of swap required
    t                 #press t to change the partition type to 82 (because partition type 82 is well supported for swap)
    8                 #enter the partition no on which u want to create swap(here i am creating on /dev/hda8 partition)
    82               #specifying the partition type
    p                 #press p to print the partition table and to just conform the /dev/hda8 partition type
    w                #press w for writing the changes to partition table (if suppose if u have any problem or trouble just                                           press q to quit from fdisk utility without any problem)

    Step5:update the partition table changes to kernel so that there is no need to restart the system/server


    Step6:Permanently mounting the partition details,in order to do this one we have to update the /etc/fstab file

    #vi /etc/fstab

    /dev/hda8    swap    swap    defaults    0 0

    enter the above entires in to fstab file,save it and exit from editing /etc/fstab file


    Step7:formatting/creating swap signature on the newly created partition

    #mkswap /dev/hda8

    Note:stpe6 and step7 are interchangeable.

    Step8:update the mount table to kernel

    #mount -a

    Step9:now on the swap so that it can be available for use.

    #swapon -a

    Step10:check weather the swap is updated or not

    #free -m   
    #swapon -s 
    #cat /proc/swaps

    Removing swap:
    Step1:Before doing any thing with swap first we have to switch of the swap

    #swapoff -a

    Step2:Remove/comment the entry of swap from /etc/fstab file

    #vi /etc/fstab

    then save and exit
    Step3:update the kernel about mount table changes

    #mount -a

    Step4:Remove the partition used by swap

    #fdisk /dev/hda8

    d                #press d to delete the partition
    8                #specify the partition no to be deleted 
    w                #press w to write the changes to partition table and quit the fdisk utility

    Step5:update the partition table changes to kernel with out rebooting the system/server


    Step6:now on the swap 

    #swapon -a

    Step7:now check weather swap is updated properly or not

    #free -m   
    #swapon -s 
    #cat /proc/swaps

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