Large File Support in Linux

To support files larger than 2 GiB on 32-bit systems, e.g. x86, PowerPC and MIPS, a number of changes to kernel and C library had to be done. This is called Large File Support (LFS). The support for LFS should be complete now in Linux and this article should give a short overview of the current status.
64 bit systems like Alpha, IA64 and x86-64 don't have problems with large files but do support the new interfaces also. In this case the new interface is mainly an alias to the normal interface.
The LFS support is done by the Linux kernel and the GNU C library (aka glibc).

Limits

LFS raises the limit of maximal file size. For 32-bit systems the limit is 2³¹ (2 GiB) but using the LFS interface on filesystems that support LFS applications can handle files as large as 2⁶³ bytes.
For 64-bit systems the file size limit is 2⁶³ bytes unless a filesystem (like NFSv2) only supports less.

LFS in Glibc 2.1.3 and Glibc 2.2

The LFS interface in glibc 2.1.3 is complete - but the implementation not. The implementation in 2.1.3 contains also some bugs, e.g. ftello64 is broken. If you want to use the LFS interface, you need to use a glibc that has been compiled against headers from a kernel with LFS support in it.
Since glibc 2.1.3 was released before LFS support went into Linux 2.3.X/2.4.0-testX, some fixes had to be made to glibc to support the kernel routines. The current stable release of glibc is glibc 2.2.3 (2.2 was released in November 2000) and it does support all the features from Linux 2.4.0. Glibc 2.2.x is now used by most of the major distributions in their latest release (e.g. SuSE 7.2, Red Hat 7.1). glibc 2.2 supports the following features that glibc 2.1.3 doesn't support:

• getdents64 system call
• 64 bit file locking interface (see below for details)

Programs compiled against glibc 2.1.3 will work on a LFS system, there's no need to recompile the programs (with the exception of the 64 bit fcntl locking). Only glibc needs to be updated to support LFS.
Note that glibc 2.0 and libc5 do not support LFS at all.

Locking on Large Files is Not Supported withfcntl/lockfin Glibc 2.1.x

Locking via fcntl/lockf doesn't work with large files in glibc 2.1.3. The support has been added in Linux 2.4.0-test7 to the kernel and needed incompatible changes to glibc, only glibc 2.2 does handle them. This means:

• You can't use the flags F_GETLK64, F_SETLK64 and F_SETLKW64 with fcntl when you use glibc 2.1.x. If your programs use them now, they fail. They also need to be recompiled with glibc 2.2 which will support these fcntl flags.
• lockf64 only works on files < 2 GiB with glibc 2.1.x, it does work with glibc 2.2 and no recompilation is needed.

LFS in the Linux Kernel

Since Linux 2.4.0-test7 most of the kernel interface is included into the kernel. The open problems and restrictions are described below.

File Systems

We can separate two levels of LFS compliance in the file systems:

1. Full support for files > 2 GiB and O_LARGEFILE
2. Limited LFS support: it gives proper EINVAL/EFBIG/EOVERFLOW error messages when you try to use O_LARGEFILE or positions > 2 GiB.

At least the second level should be generally reachable, but is some work to audit all the weird file systems.
Some bugs in NFSv2 regarding (2) have been fixed already, but some are missing (like the O_LARGEFILE check). Other file systems probably miss it too. A complete audit of all file systems is needed (see also the 2.4 kernel TODO page at http://linux24.sourceforge.net/).
The situation about the different filesystems used in Linux 2.4.0 and later can be summarized as follows:

ext2/ext3

Full support for LFS

NFSv2

Cannot handle LFS due to protocol restrictions (limited to 2 GiB - 1); limited LFS support but expect some bugs

NFSv3

The protocol is ok, but I'm not sure about the Linux implementation status

ReiserFS 3.5.x (not part of the kernel, separate patch)

Does not support LFS

ReiserFS 3.6.x (part of kernel 2.4.1 and newer)

Full support for LFS if the new on disk format is used. This format is incompatible to the format used by 3.5.x (see below for some more details).

coda

Does not work with LFS (local cache issues, protocol is ok)

UFS

Full support for LFS (although not complete vs. O_LARGEFILE flag use)

minix

limited to 2 GiB - 1 (file size is limited to 65804 MiB but note that filesystem size is limited to 64 MiB - but holes are allowed)

SysV (aka SCO)

limited to 2 GiB -1

msdos

limited to 2 GiB - 1

umsdos

based on msdos, limited to 2 GiB - 1

smbfs

Older protocols are limited to 4 GiB - 1. SMB extensions allow 64 bit filesystems. Linux smbfs implementation is currently limited to 2 GiB - 1.

NCPfs

protocol is limited to 4 GiB - 1, Linux implementation to 2 GiB - 1

JFS

Should work with LFS (for details about JFS see http://oss.software.ibm.com/developer/opensource/jfs)

XFS

Should work with LFS (for details about XFS see http://http://linux-xfs.sgi.com/projects/xfs/)

other file systems

I don't have any information yet, feel free to send me updates.

Note for ext2

When files > 2 GiB are created in ext2 older kernels will mount file systems only read-only (it sets a read-only compatibility flag).

Note for ReiserFS

Chris Mason wrote:

Disks formatted with the current 2.2 code are called our 3.5 disk format. They will not support large files under any kernel (even the 2.4 code).
But, you can mount a 3.5 disk format under the 2.4 kernel code, and use -o conv. This will turn on large file support for the old disks, but only new files will be allowed to grow past 2 GiB.
Once you mount with -o conv, you can't mount under 2.2 any more. We are testing a back port of the LFS disk format to 2.2, it should be ready soon. It has the same -o conv mount option that our 2.4 code has, so all the same rules will apply.

rlimit64 Is Not Supported

The Linux kernel doesn't support a 64bit rlimit system call yet, glibc supports getrlimit64 and setrlimit64 but wraps too large values to RLIMIT_INFINITY.

Using LFS

For using LFS in user programs, the programs have to use the LFS API. This involves recompilation and changes of programs. The API is documented in the glibc manual (the libc info pages) which can be read with e.g. "info libc".
In a nutshell for using LFS you can choose either of the following:

• Compile your programs with "gcc -D_FILE_OFFSET_BITS=64". This forces all file access calls to use the 64 bit variants. Several types change also, e.g. off_t becomes off64_t. It's therefore important to always use the correct types and to not use e.g. int instead of off_t. For portability with other platforms you should use getconf LFS_CFLAGS which will return -D_FILE_OFFSET_BITS=64 on Linux platforms but might return something else on e.g. Solaris. For linking, you should use the link flags that are reported via getconf LFS_LDFLAGS. On Linux systems, you do not need special link flags.
• Define _LARGEFILE_SOURCE and _LARGEFILE64_SOURCE. With these defines you can use the LFS functions like open64 directly.
• Use the O_LARGEFILE flag with open to operate on large files.

A complete documentation of the feature test macros like _FILE_OFFSET_BITS and _LARGEFILE_SOURCE is in the glibc manual (run e.g. "info libc 'Feature Test Macros'").
The LFS API is also documented in the LFS standard which is available at http://ftp.sas.com/standards/large.file/x_open.20Mar96.html.

LFS and Libraries other than Glibc

Be careful when using _FILE_OFFSET_BITS=64 to compile a program that calls a library or a library if any of the interfaces uses off_t. With _FILE_OFFSET_BITS=64 glibc will change the type of off_t to off64_t. You can either change the interface to always use off64_t, use a different function if _FILE_OFFSET_BITS=64 is used (like glibc does). Otherwise take care that both library and program have the same _FILE_OFFSET_BITS setting. Note that glibc is aware of the _FILE_OFFSET_BITS setting, there's no problem with it but there might be problems with other libraries.

Distributions with LFS Support

SuSE 7.0

Release 7.0 of SuSE Linux supports LFS on all supported platforms. The kernel of SuSE 7.0 is based on Linux 2.2.16.
The LFS support in the SuSE Linux kernel is the same as in the development kernel 2.4.0-test1 for the file systems which are in both kernels, glibc supports all the features of the kernel. The different filesystems are ReiserFS (so far only in SuSE, the 2.2 port doesn't support LFS) and NFSv3 (not available in SuSE 7.0). This means that you need to use ext2 as file system for LFS.
Both Linux 2.4.0-test1 and SuSE 7.0 do not support the getdents64 system call and the 64 bit locking interface. These are only implemented in Linux 2.4.0-test8 and newer.

SuSE 7.1

Release 7.1 of SuSE Linux supports LFS on all supported platforms. SuSE 7.1 comes with kernels based on 2.4.0 and 2.2.18.
The 2.2.18 kernel support LFS with the ext2 file system. The 2.4.0 kernel supports LFS with the ext2 and NFSv3 filesystems and additionally with the ReiserFS filesystem if the new ReiserFS format (incompatible to the 2.2 format) is used instead of the default 2.2 format.
SuSE 7.1 comes with glibc 2.2 that supports the full LFS interface. But the 2.2.18 kernel only does not support the 64-bit filelocking and the getdents64 calls.

SuSE 7.2 and newer

The kernel support for LFS is like the one in 7.1.

Other Distributions

Since I can't verify each and every distribution, I have to trust others for the following information.

Debian

The current stable release (Debian 3.0, codename "woody") has LFS support.

Red Hat

The beta called Fisher was the first to have LFS support (thanks to Russ Marshall). Current Red Hat releases like Red Hat 8 have LFS support.
Tim Small <tim@digitalbrain.com> send the following special combo-gotcha for Red Hat 6.2 (and probably other older distros as well):
The 'ulimit' command which is built into bash 1.x (the default for Red Hat 6.2) uses the 32 bit versions of the system calls. The way that glibc currently behaves means that requests to the 32bit setrlimit, or getrlimit will translate 'unlimited' to '2³¹ - 1' in both directions (I would argue that setting a limit to RLIM_INFINITY using the 32bit interface should end up in a call to the 64 bit setrlimit variant with the 64 bit RLIM_INFITIY).
The default PAM configuration for sshd (/etc/pam.d/sshd), includes the line:

session    required     /lib/security/pam_limits.so

Which fiddles about with various limits (using the 32bit versions of the calls).
If you log-in using ssh, and use bash 1.x to view the limits, you will be told that your file size is unlimited, when it is in fact set to 2097151 (1024 byte) blocks!
Workaround:

• Either:
  • Comment out the line in /etc/pam.d/sshd (note that limits set in /etc/security/limits.conf will no longer be effective for ssh logins)
  • Or: Rebuild the pam package with 64 bit support
• Install the bash2 RPM
• Either:
  • rename the old bash, and symlink /bin/bash2 to /bin/bash (you may want to keep /bin/sh pointing at the old bash, if you are worried about compatibility)
  • Or: use vipw to change users over to /bin/bash2

Other...

I don't have any other information yet. Feel free to send me detailed information about distributions if they supports LFS.

Some Other Often Requested Data about Filesystems

Please send me information to fill in the missing bits.

Maximum On-Disk Sizes of the Filesystems

Filesystem	File Size Limit	Filesystem Size Limit
ext2/ext3 with 1 KiB blocksize	16448 MiB (~ 16 GiB)	2048 GiB (= 2 TiB)
ext2/3 with 2 KiB blocksize	256 GiB	8192 GiB (= 8 TiB)
ext2/3 with 4 KiB blocksize	2048 GiB (= 2 TiB)	8192 GiB (= 8 TiB)
ext2/3 with 8 KiB blocksize (Systems with 8 KiB pages like Alpha only)	65568 GiB (~ 64 TiB)	32768 GiB (= 32 TiB)
ReiserFS 3.5	2 GiB	16384 GiB (= 16 TiB)
ReiserFS 3.6 (as in Linux 2.4)	1 EiB	16384 GiB (= 16 TiB)
XFS	8 EiB	8 EiB
JFS with 512 Bytes blocksize	8 EiB	512 TiB
JFS with 4KiB blocksize	8 EiB	4 PiB
NFSv2 (client side)	2 GiB	8 EiB
NFSv3 (client side)	8 EiB	8 EiB

Note Kernel Limitations: The table above describes limitations of the on-disk format. The following kernel limits exist:

• On 32-bit systems with Kernel 2.4.x: The size of a file and a block device is limited to 2 TiB. By using LVM several block devices can be combined enabling the handling of larger file systems.
• 64-bit systems: The sizes of a filesytem and of a file are limited by 2⁶³ (8 EiB). But there might be hardware driver limits that do not allow to access such large devices.
• Kernel 2.6: For both 32-bit systems with option CONFIG_LBD set and for 64-bit systems: The size of a file system is limited to 2⁷³ (far too much for today). On 32-bit systems (without CONFIG_LBD set) the size of a file is limited to 2 TiB. Note that not all filesystems and hardware drivers might handle such large filesystems.

Note in the above: 1024 Bytes = 1 KiB; 1024 KiB = 1 MiB; 1024 MiB = 1 GiB; 1024 GiB = 1 TiB; 1024 TiB = 1 PiB; 1024 PiB = 1 EiB (check http://physics.nist.gov/cuu/Units/binary.html)

Maximum Number of Partitions

An IDE disk has 64 minors, one is used for the full disk and therefore 63 partitions are possible. A SCSI disk has 16 minors and therefore only 15 partitions maximal.

Recently supported applications on Red Hat Enterprise Linux 6

 

Recently supported applications on Red Hat Enterprise Linux 6

Red Hat® has a broad ecosystem of independent software vendors (ISVs) who have tested and certified their applications on Red Hat Enterprise Linux 6. Thanks to these partners, our customers can benefit from the new technologies and cost savings in Red Hat Enterprise Linux immediately.

Linux Command

Linux Command to find the system configuration and hardware information

Q. What is the command to find the system configuration on Linux operating system using command line (text) mode?

A. Most of the hardware information can be extracted from /proc file system, for example display CPU and Memory information, enter:
cat /proc/meminfo
cat /proc/cpuinfo

Distro news and release’s

• Linux Royal

So got the Royal Lite build done. Removed all things Unity/Gnome-shell/and classic. So it has only Cinnamon and Cinnamon 2D for DE options at bootup. Also removed a bunch of apps/icons/themes. Added Royal Icons/Cinnamon Themes. Also installed VLC/Restricted Extras/and of course Remastersys so I could build it. Wanted to make it a bit smaller but not at the cost of Libre Office so I left it. It has a minimal amount of apps though, I got it down to 971mb, so about 200mb bigger then Ubuntu and about 40% the size of full Royal builds. Even in live it only booted using 199mb of ram as noted in the screenshot here. Will try and get it uploaded tomorrow. The only thing I have left to test is installing it.

• Crunchbang

well as we know crunchbag is more for old/light computer’s and servers and what the different on this released
they been some bug fixes in the installer on the DVD for the lastest release they had some bug the were having issues installing the Distro an error message appeared just before grub boots up properly!
And other minor changers like?

• Iceweasel 18
• vlc instead of gnome mplayer (popular)
• A Policy Kit Local Authority file has been added to enable easy mounting of internal drives within Thunar
• xfce4-power-manager has been patched to fix a long standing issue whereby the battery status icon would cause a visual error within tint2′s system tray, after a system had been suspended and resumed.

And as well the changers are kept minimum and any other crunchbag users will not need to upgrade to the next version unless they wish to help with test installations proceeding?

• Opensuse 12.3

go and get opensuse while it piping hot
no but opensuse is a redhat base with kde on top of it but what this make it special is the it comes with a package manager which is really good better the (gnome package manager) the fedora uses. it use something called YaST graphical user interface and Zypper as a command line interface so it both worlds plus opensuse has a rolling released distro called tumbleweed the has the latest package bit like (arch)
this beta come with the latest kde 4.10 and as well been ironing bugs and the latest kernel 3.7.1 so more support in arms computer and new support for hardware and as well

• support for metadata checksums and improved quota support in Ext4
• I/O failure statistics, subvolume quotas, quota groups, snapshot diffs, faster fsync and the ability to disable copy-on-write on a per-file base in btrfs
• userspace probes for performance profiling with tools like Systemtap or perf and a new “perf trace” tool modeled after strace.
• Many improvements to networking. The TCP protocol performance work with support for the TCP “Fast Open” mode for both clients and servers and TCP Early Retransmit (RFC 5827) as well as inclusion of the a “TCP small queues” feature and a new network queue management algorithm designed to fight bufferbloat. Other low-level protocol enhancements include support for checkpointing and restoring TCP connections and a new tunneling protocol that allows to transfer Layer 2 Ethernet packets over UDP. New is experimental SMBv2 protocol support as well as stable NFS 4.1 and parallel NFS support and the ability to have safe swapping over NFS/NBD.
• The kernel now allows for Android-style opportunistic suspend and has support for suspending to disk and memory at the same time which prevents these “yup, ran out of battery so now you lost data” annoyances with suspend-to-ram.
• In the security area we see added support for signed kernel modules, the Intel “supervisor mode access prevention” (SMAP) security feature, VFIO, which allows safe access from guest drivers to bare-metal host devices and a sandboxing mechanism that allows to filters syscalls.
• Other improvements include the ability to do SCSI over Firewire and USB, support for the PCIe D3cold power state; and the usual huge number of new and improved drivers.

and plus on top of this there will be the latest version of libreoffice so don’t you worry about thing?

• Fedora 18

fedora 18 has been released yesterday with the UEFI secure boot support so any windows 8 computer the has this feature it will work out of the box and a new installer for the the new users to install a lot easier. with advance settings from a new comer from Ubuntu (or any other Ubuntu base distro wants to try something new)?

by default this is what it looks like very nice with the latest gnome 3.6 you are going to be right at home. with this distro and for the people who don’t know gnome. gnome is a desktop interface that use to be popular an till the gnome shell was released but don’t let it fool you this is good to add extra feature like gnome extensions to make that experience a lot better for the people the like’s gnome.

like the installer the installer called (Anaconda)
ok now for the gnome haters cinnamon and mate is been released into there repos by default so you can install mate or cinnamon for a change over or just install the respins it’ s really up to you?
and upgrade feature there is a program called fedup upgrade fedora 18 and as wel can upgrade offline as well so the many updates can still be made on the fly, some packages will require a system restart. The system will boot into a special update mode “in order to avoid problems related to conflicts of libraries and services that are currently running with those on disk

• Fuduntu 2013.1

fuduntu has been updated with the lastest kernel 3.6 with driver support aka (jocky) plus they even released the netflix desktop for useful film watching since the last release they had a power manager called jupiter (mainly for eee pc’s) now that gone because jupiter power managemet development has stopped sorry everyone
if people dont know what fuduntu is well it’s an easy use system (as always) the a rolling released system they use to be base on fedora but now independent it use the gnome2 interface which that good for people who love the gnome 2 interface (sorry mate)

Type of Installation in Linux:

What type of installation should I do? (Dual Boot / Live CD / Fresh Install / Virtual Installation)
One of the things that makes Linux special is that it can “play nice” with other operating systems. You can run Linux alongside of other operating systems quite easily. The most popular installation process for installing Linux is to install a “Fresh Installation of Linux” with no other operating system in place. This allows the computer to dedicated 100% of its resources to running Linux. However, it is quite easy to install Linux as a one of a series of operating systems that a computer has available to it.
Here are the most popular ways to install/run Linux on your computer


Dual Booting - If you want to keep an existing operating system, and install Linux as well, you will have what is known as a "dual-boot" system. That means that you have a PC that can use two different operating systems, and during the boot process you will need to decide which one you would like to boot into.

Author’s Note: Dual Booting between Windows and Linux is becoming somewhat less popular due to the rise of Virtual Machines. If you like the idea of running two operating systems, then you may want to consider running Linux as a VM inside of another operating system instead.


Live CD/DVD Booting Linux – If you are just looking to try Linux out to see if you like it, but don't want to commit to wiping out your main operating system, you may want to consider trying Linux from a "Live CD/DVD". Many Linux installations provide the option of downloading and running Linux as a "Live CD", which means that Linux runs as a completely bootable operating system from the CD/DVD. The files are loaded into your computer’s memory, rather than being run for a hard disk drive. In layman's terms, this means that you can run Linux from a CD/DVD, and then when you reboot your PC, and remove the CD/DVD, it will boot back into its old operating system without any difference to your PC. This gives you an easy way to try out several distributions of Linux until you find the one that you like!

Using a "Live CD/DVD" is also a popular method of rescuing files from a corrupted operating system, more on this later...


Linux as a VM inside another Operating System – If you like your current (non-linux) desktop operating system, but would like an easy way to access a Linux desktop or run your favorite open source software, you may want to consider running Linux as a VM inside another operating system. There are a number of ways to do this, but one simple one would be to download and install a Virtual Server application, and then install your Linux distribution under that host software. This topic is covered in the more advanced tutorials on this website… I think that I should pause here and say that everything that you can do with your “other” operating system, you can do with Linux. That means word processing, databases, spreadsheets, Internet browsers, e-mail, photo touch-ups, MP3, CD Players, cameras and then there are a lot of things that Linux has to offer on top of all that that other operating systems don't.


Fresh Install of Linux – This method is by far the most popular installation method available. In this approach, you “take the plunge” and format your computer’s hard drive and install Linux from a CD/DVD. Linux then runs as your computers only operating system.

The 4 Best Free Linux Anti-Virus Programs

Does a Linux user need antivirus software? Not really: infecting a Linux machine is pretty hard to do. That doesn’t mean there aren’t good reasons to have scanning software around, though.
If you insert your thumb drive regularly into Windows computers, for example, it might be infected, meaning you’re spreading malware with it and not even knowing it (see: Stuxnet).  Antivirus software for Linux gives you a quick way to check your drives without any risk of infecting yet another Windows machine.

It’s also a great tool to have around if you regularly help your Windows-bound friends and family recover from viruses. Remove their hard drive and plug it into your computer, or just use your Linux machine to clean their external drives.
Most Linux antivirus software focuses on removing Windows viruses, and function as one-time-scan tools rather than the Windows-style, sit-in-your-tray-and-protect-you products that’s common in Windowsland. Such software is not essential for Linux users, but is pretty handy.

Avast

Avast, the anti-virus program I previously decided has the coolest name for an anti-virus program, also sports a pretty great Linux GUI. As you can see it looks right at home on my Ubuntu desktop. This makes it easy to update defintions and scan the folders of your choice.

It’s also really easy to install Avast for Linux. Just download your package of choice (rpm, deb and tar.gz), then register for a free year of Avast usage. If you don’t register, you won’t be able to use the program:

Happily, registering gives you one year of free non-commercial usage, so you won’t need to do this frequently. And you’ll have access to a sleak GUI and all of the definitions Avast has to offer.

BitDefender

This is one of my favorites. BitDefender frequently finds, for me, viruses that other scanners miss. Being able to use it from Linux is a big plus.
Finding it for Linux isn’t straightforward, though. You need to head over to the BitDefender for Unices page, then click the “evaluation version” button. You’ll be given a form to fill in, and when you’re done you’ll get a license valid for one month and a link to downloads.
The downloads look like this:

Find your platform and package of choice (ignoring, for now, the “.run” file extension) and download it (right-click and click “save as“, or your browser might try to open the entire file as a text document.) Change the permissions of the file to allow it to be executed. If you don’t know how to do this, the simplest way is to right-click it, click “Properties,” open the permissions tab, then click “allow executing.”
Finally, open your command line. Browse to the folder with the file, then type “sudo ./[filename]“, where [filename] is the name of the BitDefender version you downloaded. You’ll need to read an EULA before BitDefender will finally install (mercifully, using the package manager of your choice).
Why you need to go through all of that I don’t know, but it’s worth it. You now have access to a complete version of BitDefender. You can scan any file, update with the click of a button and much more. The graphical interface is identical to that of the BitDefender Live CD.
The free license lasts for only 30 days, but you can apply for another one if you need to.

ClamAV

Completely open source, ClamAV is probably the most famous Linux anti-virus. Using it requires some command line knowledge, but there is a basic GUI for running scans:

Installing ClamAV is simple; it’s in the repositories of most Linux distributions. Install the “clamtk” package and you’ll get the above GUI and you’ll have everything you need; or, if you’re an Ubuntu user, simply click here to download ClamAV.
Once you’ve installed ClamAV, fire up your terminal and run “sudo freshclam“.  This will update ClamAV’s virus definitions for you.
Now you simply need to run clamtk. Fire it up from the command line, or find the program called “Virus Scanner” in the “Accessories” section of the menu. Use the GUI to scan any folder, or your entire system. Or, if you prefer, use “clamscan” from the command line. Either way you’ve got some quality, free anti-virus protection.

AVG

Those familiar with AVG’s Windows interface will be disappointed: AVG for Linux has no GUI. This command line scanner does offer the same virus definitions of AVG’s famous Windows program, though.
You can easily download AVG for Linux. You’ll find packages for every major distro, including .deb and .rpm files.
Using the program is straightforward. First you need to start the AVG daemon: run “sudo avgctl –start“. Then you can use “sudo avgupdate” to update the software, and “avgscan” to scan a given file.

There’s not a whole lot else to say about this one, although I hope AVG releases a Linux GUI again soon (previous versions offered one).

File Extensions in Linux

Understanding File Extensions in Linux
Extensions are file name suffixes that start with a period. Usually, they are two or three letters long. 

Linux can read many file extensions used by other platforms, such as 

jpg for a graphic file, or .html for a web file. It can also use 
them for mime types. However, Linux does not always use extensions to identify file types. 

Often, the directory where a file is placed is a better indication of what type of file it is. 

However, Linux does use a few regular extensions.

Extensions Used in Linux

Extension	File Type
.bz2	A file compressed using bzip2 .
.c	A file written in the C programming language.
.conf	A configuration file. In some cases, "conf" is used in a file name, but not as an extension.
.deb	A Debian package for installing software.
.lock	A lock file that prevents the use of another file.
.rpm	A Red Hat package file. Although you can sometimes use .rpm s in Debian, doing so can have unexpected results and is not generally recommended. You can also convert packages using the alien utility .
.so	A shared object (a library or module).
.src	A source code file. Written in plain text, a source file must be compiled to be used.
.tar	A single file made of a collection of files archived using the tar command.
.tar.gz	A single file made of a collection of files archived using the tar command, then compressed used the gzip command.
.tgz	A single file made of a collection of files archived using the tar command, then compressed used the gzip command.
.gz	A file compressed using the gzip command.
.txt	a plain ASCII text file
.ps	a PostScript file; formatted for printing
.au	an audio file
.wav	an audio file
.xpm	an image file
.jpg	a graphical or image file, such as a photo or artwork
.gif	a graphical or image file
.pdf	an electronic image of a document
.a	an archive file
.h	a C or C++ program language header file
.cpp	a C++ program language source code file
.o	a program object file
.php	a PHP Script
.sh	a Shell Script
.png	a graphical or image file
.tcl	a TCL script
.pl	a Perl script
.html/.htm	an HTML file

5 Reasons Why Linux is More Secure than Windows

"Security through obscurity" may be a catchy phrase, but it's not the only thing that's catching among Windows users.

The expression is intended to suggest that proprietary software is more secure by virtue of its closed nature. If hackers can't see the code, then it's harder for them to create exploits for it--or so the thinking goes.

Unfortunately for Windows users, that's just not true--as evidenced by the never-ending parade of patches coming out of Redmond. In fact, one of Linux's many advantages over Windows is that it is more secure--much more. For small businesses and other organizations without a dedicated staff of security experts, that benefit can be particularly critical.

Five key factors underlie Linux's superior security:

1. Privileges

Linux systems are by no means infallible, but one of their key advantages lies in the way account privileges are assigned. In Windows, users are generally given administrator access by default, which means they pretty much have access to everything on the system, even its most crucial parts. So, then, do viruses. It's like giving terrorists high-level government positions.

With Linux, on the other hand, users do not usually have such "root" privileges; rather, they're typically given lower-level accounts. What that means is that even if a Linux system is compromised, the virus won't have the root access it would need to do damage systemwide; more likely, just the user's local files and programs would be affected. That can make the difference between a minor annoyance and a major catastrophe in any business setting.

2. Social Engineering

Viruses and worms often spread by convincing computer users to do something they shouldn't, like open attachments that carry viruses and worms. This is called social engineering, and it's all too easy on Windows systems. Just send out an e-mail with a malicious attachment and a subject line like, "Check out these adorable puppies!"--or the porn equivalent--and some proportion of users is bound to click without thinking. The result? An open door for the attached malware, with potentially disastrous consequences organizationwide.

Thanks to the fact that most Linux users don't have root access, however, it's much harder to accomplish any real damage on a Linux system by getting them to do something foolish. Before any real damage could occur, a Linux user would have to read the e-mail, save the attachment, give it executable permissions and then run the executable. Not very likely, in other words.

3. The Monoculture Effect

However you want to argue the exact numbers, there's no doubt that Microsoft Windows still dominates most of the computing world. In the realm of e-mail, so too do Outlook and Outlook Express. And therein lies a problem: It's essentially a monoculture, which is no better in technology than it is in the natural world. Just as genetic diversity is a good thing in the natural world because it minimizes the deleterious effects of a deadly virus, so a diversity of computing environments helps protect users.

Fortunately, a diversity of environments is yet another benefit that Linux offers. There's Ubuntu, there's Debian, there's Gentoo, and there are many other distributions. There are also many shells, many packaging systems, and many mail clients; Linux even runs on many architectures beyond just Intel. So, whereas a virus can be targeted squarely at Windows users, since they all use pretty much the same technology, reaching more than a small faction of Linux users is much more difficult. Who wouldn't want to give their company that extra layer of assurance?

4. Audience Size

Hand-in-hand with this monoculture effect comes the not particularly surprising fact that the majority of viruses target Windows, and the desktops in your organization are no exception. Millions of people all using the same software make an attractive target for malicious attacks.

5. How Many Eyeballs

"Linus' Law"--named for Linus Torvalds, the creator of Linux--holds that, "given enough eyeballs, all bugs are shallow." What that means is that the larger the group of developers and testers working on a set of code, the more likely any flaws will be caught and fixed quickly. This, in other words, is essentially the polar opposite of the "security through obscurity" argument.

With Windows, it's a limited set of paid developers who are trying to find problems in the code. They adhere to their own set timetables, and they don't generally tell anyone about the problems until they've already created a solution, leaving the door open to exploits until that happens. Not a very comforting thought for the businesses that depend on that technology.

In the Linux world, on the other hand, countless users can see the code at any time, making it more likely that someone will find a flaw sooner rather than later. Not only that, but users can even fix problems themselves. Microsoft may tout its large team of paid developers, but it's unlikely that team can compare with a global base of Linux user-developers around the globe. Security can only benefit through all those extra "eyeballs."

Once again, none of this is to say that Linux is impervious; no operating system is. And there are definitely steps Linux users should take to make their systems as secure as possible, such as enabling a firewall, minimizing the use of root privileges, and keeping the system up to date. For extra peace of mind there are also virus scanners available for Linux, including ClamAV. These are particularly good measures for small businesses, which likely have more at stake than individual users do.

It's also worth noting that security firm Secunia recently declared that Apple products have more security vulnerabilities than any others--including Microsoft's.

Either way, however, when it comes to security, there's no doubt that Linux users have a lot less to worry about.

RedHat: History of releases

RedHat: History of releases

     RedHat is the most known and biggest company in the world whose business is entirely based on Linux. It's the first distribution maker that has quoted its shares at Nasdaq and one of the not so many companies that has built a successful Linux business model.
Originally founded by Marc Ewing, it was purchased in 1995 by Bob Young's ACC Bookstores. During the following years, version after version, it has gained a reputation of distro good for servers (even if by far not the best one, according to purists) with easy installation and configuration tools.

The first public release of Red Hat Linux (version 1.0) is dated 1994, after the older historic distro as Slackware, but still largely before the big Linux boost of the following years.

Chronology of Red Hat releases

RedHat 1.0 (Mother's Day), November 3, 1994

RedHat 1.1 (Mother's Day+0.1), August 1, 1995

RedHat 2.0, September 20, 1995

RedHat 2.1, November 23, 1995

RedHat 3.0.3 (Picasso), May 1, 1996

RedHat 4.0 (Colgate), October 8, 1996

RedHat 4.1 (Vanderbilt), February 3, 1997

RedHat 4.2 (Biltmore), May 19, 1997

RedHat 5.0 (Hurricane), December 1, 1997

RedHat 5.1 (Manhattan), May 22, 1998

RedHat 5.2 (Apollo), November 2, 1998

RedHat 6.0 (Hedwig), April 26, 1999

RedHat 6.1 (Cartman), October 4, 1999

RedHat 6.2 (Zoot), April 3, 2000

RedHat 7 (Guinness), September 25, 2000

RedHat 7.1 (Seawolf), April 16, 2001

RedHat 7.2 (Enigma), October 22, 2001

RedHat 7.3 (Valhalla), May 6, 2002

RedHat Enterprise Edition 2.1 AS (Pensacola), May 6 2002

RedHat 8.0 (Psyche), September 30, 2002

RedHat 9 (Shrike), March 31, 2003

The Fedora and Red Hat Projects merged September 22, 2003 when RedHat made the discussed choice to split its product line in 2 main branches: the free and open Fedora and the commercial, enterprise-ready, Red Hat Enterprise Edition.

RedHat Enterprise Edition 3.0 (Taroon), October 22 2003

Fedora Core 1 (Yarrow), was published November 2003

Fedora Core 1.90 (FC2 Test 1), February 4, 2004
Fedora Core 2 (Tettnang), May 11, 2004

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