Difference between revisions of "Linux"

Latest revision as of 20:06, 24 October 2014

Linux is a computer operating system and its kernel. It is one of the most prominent examples of free software and of open-source development: unlike proprietary operating systems such as Windows and Mac OS, all of its underlying source code is available to the public and anyone can freely use, modify, improve, and redistribute it.

Kernel

The kernel is the core piece of the Linux operating system.

The kernel manages the resources of the Linux OS; such as the following:

• File management
• Multitasking
• Memory management
• I/O management
• Process management: /proc/
• Device management: /dev/
• Networking support (including IPv4 and IPv6)
• Virtual memory, shared libraries, demand loading, etc.

The kernel decides who will use these resources, for how long, and when.

Keyboard shortcuts

Ctrl+Alt+Del 

shut down computer

Ctrl+Alt+(F1,F2,...,Fn) 

switch to n-th console

Alt+<- | Alt+-> 

switch to next|previous virtual terminal

Ctrl+k 

clear CLI from cursor position to end of line

Ctrl+u 

clear CLI from cursor position to beginning of line

Ctrl+a 

move cursor to beginning of CLI

Ctrl+l 

clear console screen

Ctrl+z 

pause (see 'bg' and 'fg')

Ctrl+r 

incremental search of previous command history

Tab 

CLI-autocompletion

Scroll Lock 

lock terminal input/output

Shift+pgUp | Shift+pgDn 

scroll console buffer up|down

Ctrl+Alt++ | Ctrl+Alt+- 

change screen resolution higher|lower

Ctrl+Alt+Bksp 

kill X-server (note: running aps will be terminated)

Alt+F2 

run command box (on KDE)

Ctrl+Shift+NumLock 

turn keypad into mouse keys

Tutorials

Beginner

• Linux 101 — level 1
• Linux 102 — level 2
• Linux 103 — level 3

Intermediate

• Linux 201 — level 1
• Linux 202 — level 2
• Linux 203 — level 3

Advanced

• Linux 301 — level 1
• Linux 302 — level 2
• Linux 303 — level 3

Distributions

Linux is predominantly used as part of a Linux distribution (commonly called a 'distro'). These are compiled by individuals, loose-knit teams, and various professional organizations. They include additional system software and application programs, as well as certain processes to install these systems on a computer.

My favourite distributions include:

• SuSE — my primary operating system since 1999. (see also: openSUSE)
• Mandriva
• Damn Small Linux (DSL) — A live CD designed for MiniCD with a hard drive install option.
• Damn Vulnerable Linux — a good distro for learning about Linux security.
• Knoppix — my favourite LiveCD (version: 5.1.1CD-2007-01-04; kernel 2.6.19.1; KDE 3.5.5; package list, cheat codes)
• see also: Google Linux Software Repositories

How to determine which Linux distribution is installed

Normally, the output of one of these should tell you which distro is installed:

cat /proc/version
uname -a
cat /etc/*rel*
echo /etc/*_ver* /etc/*-rel*; cat /etc/*_ver* /etc/*-rel*
cat /etc/version
cat /etc/issue
cat /etc/issue.net

The following is normally where various distros store the release/version information:

Annvix: /etc/annvix-release
Arch Linux: /etc/arch-release
Arklinux: /etc/arklinux-release
Aurox Linux: /etc/aurox-release
BlackCat: /etc/blackcat-release
Cobalt: /etc/cobalt-release
Conectiva: /etc/conectiva-release
Debian: /etc/debian_version, /etc/debian_release (rare)
Fedora Core: /etc/fedora-release
Gentoo Linux: /etc/gentoo-release
Immunix: /etc/immunix-release
Knoppix: knoppix_version
Linux-From-Scratch: /etc/lfs-release
Linux-PPC: /etc/linuxppc-release
Mandrake: /etc/mandrake-release
Mandriva/Mandrake Linux: /etc/mandriva-release, /etc/mandrake-release, /etc/mandakelinux-release
MkLinux: /etc/mklinux-release
Novell Linux Desktop: /etc/nld-release
PLD Linux: /etc/pld-release
Red Hat: /etc/redhat-release, /etc/redhat_version (rare)
Slackware: /etc/slackware-version, /etc/slackware-release (rare)
SME Server (Formerly E-Smith): /etc/e-smith-release
Solaris SPARC: /etc/release
Sun JDS: /etc/sun-release
SUSE Linux: /etc/SuSE-release, /etc/novell-release
SUSE Linux ES9: /etc/sles-release
Tiny Sofa: /etc/tinysofa-release
TurboLinux: /etc/turbolinux-release
Ubuntu Linux: /etc/lsb-release
UltraPenguin: /etc/ultrapenguin-release
UnitedLinux: /etc/UnitedLinux-release (covers SUSE SLES8)
VA-Linux/RH-VALE: /etc/va-release
Yellow Dog: /etc/yellowdog-release

See: here for more details.

Linux commands you should never run

NOTE: There is little, if anything, you can do to recover if you execute any of the following:

rm -rf /                # Deletes _everything_ on your computer recursively
:(){ :|: & };:          # Fork Bomb
mv ~ /dev/null          # Move everything to NULL (i.e. nowhere)
mkfs.ext3 /dev/sda      # Formats your entire hard drive
any-command > /dev/sda  # Send STDOUT of <any-command> to your HDD (i.e., overwrites your entire HDD)

See also

• Filesystem Hierarchy Standard

External links

• The Linux Kernel Archives — the primary site for the Linux kernel source, but it has much more than just Linux kernels.
• Linux Newbie Administrator Guide — (LNAG)
• Introduction to Linux - A Hands on Guide — by Machtelt Garrels (14-Mar-2006)
• The Linux Kernel Module Programming Guide
• The Linux Vault
• wikipedia:Linux

Tutorials

• Easy Linux.info — wiki site.
• HowtoForge — Linux howtos and tutorials
• Beyond Linux From Scratch
• Kernel Rebuild Guide — by Kwan Lowe
• How To Compile A Kernel - The SuSE Way — by Falko Timme on HowtoForge.com
• How To Compile A Kernel - The Mandriva Way — by Falko Timme on HowtoForge.com

Tools / resources

• Net Admin Tools

Books

• Free On-Line Linux Books
• 68 Linux Related Free E-books
• The Art of Unix Programming — by Eric Steven Raymond

Hardware compatibility

• Linux Hardware Compatibility HOWTO
• Hardware Compatibility List — on opensuse.org