Linux

What is Linux?

Linux is an UNIX compatible operating system *kernel*.

A kernel is but one (very important) part of an operating system.

This kernel was written from scratch by Linus Torvalds with assistance from a loosely-knit team of hackers across the net. It aims towards POSIX and Single UNIX Specification compliance.

Combined with the GNU utilities you get GNU/Linux which is the correct term for an complete OS.

It has all the features you would expect in a modern fully-fledged Unix, including true multitasking, virtual memory, shared libraries, demand loading, shared copy-on-write executables, proper memory management, and TCP/IP networking.

Linux was first developed for 32-bit x86-based PCs (386 or higher). These days it also runs on (at least) the Compaq AlphaAXP, SunSPARC and UltraSPARC, Motorola 68000, PowerPC, PowerPC64, ARM, Hitachi SuperH, IBM S/390, MIPS, HP PA-RISC, Intel IA-64, DEC VAX, AMD x86-64 and CRIS architectures.

Linux is easily portable to most general-purpose 32- or 64-bit architectures as long as they have a paged memory management unit (PMMU) and a port of the GNU C compiler (gcc).

Some basic commands

These Unix compatible 'commands' are not part of the Linux kernel. The are all separate programs that are used on many other operating systems. The unifying property of these commands is that they are all FreeSoftware, and most all are CopyLeft.

GNU/Linux/Unix commands A-Z
command	description	examples
bc	binary calculator	bc
cat	concatenate files and print on standard output	cat >test , cat file1 file2 >file3
cd	change working directory	cd ~
chmod	change file access permissions	chown guest.users filename
chown	change owner and group of a file	chmod u+x filename, chmod 770 filename
cmp	compare two files byte by byte	cmp file1 file2
cp	copy a file or directory	cp -d -p -R
date	show system date	date
df	show free disk space	df -h
diff	find differences between two files	diff -u file1 file2
du	show disk use of file(s) or directory	du -s
echo	display a line of text	echo "Hello world"
fg	bring a process to the foreground	fg [jobnr]
find	find files on name, date, owner, permissions etc	find ./ -name *.kdelnk
ftp	File transfer protocol	ftp ftp.nluug.nl
grep	print lines matching a pattern	ls -alR |grep txt
head	show first lines of text file	head textfile
irc	Internet Relay Chat	irc -c #squat fnord irc.xs4all.nl
jobs	show running or stopped jobs	jobs
kill	kill a process	kill -9 PID
killall	kill process by name	killall -9 netscape, killall -HUP daemon
less	a better version of more	less textfile
ls	list files in directory	ls -a -l -R
lynx	A text browser	lynx http://squat.net/ascii
mail	Basic mail implementation	echo "Test" | mail -s "Test" guest
man	show manual page on command	man command
mkdir	make directory	mkdir newdir
more	view text file screen by screen	more textfile
mv	move file or directory to another place	mv file1 file2
ncftp	A better ftp client	ncftp -u username ftp.nluug.nl
netstat	Show network statistics	netstat -r
pico	edit a text file	pico filename
pine	A mail client	pine
ping	Send small package to check if a machine is up & reaction time	ping localhost
ps	show currently running processes	ps aux
pwd	print working directory	pwd
rm	remove a file or directory	rm -r -f
rmdir	remove directory	rmdir newdir
sort	sort a file	sort filename
ssh	A more secure version of telnet	ssh -l username host.domain
tail	show last lines of text file	tail -f textfile
telnet	Remote login	telnet dds.dds.nl
top	display top CPU processes	top
touch	change file timestamps	touch -t 10210000 filename
tr	translete or delete characters	echo "test" | tr [:lower:] [:upper:]
uniq	show only the diffenent lines from a text file	uniq filename
uptime	show the time the system is running (and system load)	uptime
vi	the unix text editor	vi filename
wc	count bytes, words and lines in files	wc -l filename
who	show who is logged on	who
whoami	print effective userid	whoami
yes	output a string repeatedly until killed	yes hello

The best way to find information on how to use a command is the man command. This command tells you a lot of specific information on a command. Try man man for a start.

Some handy function keys

Linux Function keys
[CTRL]-z	Bring a program to the background
[CTRL]-c	Stop a program
[CTRL]-d	End of input file
[ALT]-[F1]..[F6]	Switch to terminal TTY1..6 (depends on configuration)
[ALT]-[F7]	Switch to X (if running)
[CTRL]-[ALT]-[F1..6]	Switch from X to text terminal
[CTRL]-[ALT]-[BACKSP]	Kill X-window (in mode 5, X will restart)
[CTRL]-[ALT]-[DEL]	Reboot or halt (depends on configuration)

copied and extended from: PUSCII - # http://www.puscii.nl/

Related

--> Debian,GNU,[[::Category:Linux Distributions]],Linus Torvalds,FSF,Unix

• Linux CD/DVD Recording

• Linux Lernmaterial

deutsch

Deutschsprachige Linux Study Guides als PDF

How to pronounce Linux?

Like Linus Torvalds says it

Jargon

<jargon />