Best Linux Guide And Command Explanation

S u p H C

Today I am going to explain you what is Linux and alot of useful Linux terminal commands.

If you still haven't decide which Linux distro to choose I would highly recommend you checking my guide:

* How To Choose The Right Linux Distribution For You *

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Linux is a Unix-like and POSIX-compliant computer operating system assembled under the model of free and open source software development and distribution. It is a freeware and generally speaking its free from Virus and other malware infections. The main form of distribution are Linux distributions. It's a bit harder to learn at first , a lot of command line stuff but when you get to grips with it it can be very rewarding.
The big thing about linux is that it is open source, which means there are virtually no license limitations so people can do what they want with it, this can be very useful for people who have very specific requirements and dont want to get involved in messy licensing as you would with windows for example.

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Linux is multi platform.

This means that by choosing Linux, you choose a portable operating system on which you can run or develop portable applications. Linux runs on Sparc(Sun), Alpha(Compaq), Mips, ARM, x86(Intel), PowerPC, 680x0(Motorola), RS6000 (IBM), and so on... So,when choosing Linux for your operating system,you open choices to you. You don't reduce your choices to no otherc hoice than Intel running IBM compatible.

Linux is not under the control of NSA.

The NSA (NationalSecurityAgency,USA) and Microsoft recognized that two sets of secret keys where shipped with Windows in order to allow either Microsoft and NSA to enter any Windows running computer in the world Linux is open source. Anybody can check if there is such a backdoor in it. NSA is working on a certificated secure version of the Linux kernel for USA use,because they know Windows is not secure.

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Note: The commands below are top 5 in my opinion not officially.

"sudo"

Code:
sudo

Sudo best thought of as ‘Superuser Do’, allows you to run commands with root/administrator permissions.

For example: You can't do:

Code:
apt-get update

If you are not logged in as "root"

So all we have to do is to add "sudo" at the beginning of the command.

Code:
sudo apt-get update

"apt-get install"

Code:
apt-get install

Allows you to install applications available in the Ubuntu Software Center and added PPAs can be installed from the command line using ‘apt-get install‘.

I.E: (Installing tor on your machine)

Code:
apt-get install tor

"top"

Code:
top

Top command which is one of the most frequently used commands in our daily system administrative jobs. Top command displays processor activity of your Linux box and also displays tasks managed by kernel in real-time. It’ll show processor and memory are being used and other information like running processes. This may help you to take correct action. top command found in UNIX-like operating systems. You can perform different actions with that , even killing processes.

"cd"

Code:
cd

‘cd’ (Change Directory) is the command used for navigating folders in the Terminal.
‘cd folder/name/’ will navigate you into that folder
To go back on folder type

Code:
cd -

Typing ‘cd‘ on its own returns you to the ‘Home’ folder
Tip: Remember you can always use the ‘Tab’ button to auto-complete commands and locations in the Terminal.

"ls"

Code:
ls

ls command is one of the most frequently used command in Linux. I believe ls command is the first command you may use when you get into the command prompt of Linux Box. We use ls command daily basis and frequently even though we may not aware and never use all the option available. In this article, we’ll be discussing basic ls command where we have tried to cover as much parameters as possible.

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Show the current date and time

Code:
date

Show this month's calendar

Code:
cal

Show current uptime

Code:
uptime

Display who is online

Code:
w

Who you are logged in as

Code:
whoami

Display information about user

Code:
finger user

Show kernel information

Code:
uname -a

Cpu information

Code:
cat /proc/cpuinfo

Memory information

Code:
cat /proc/meminfo

Show disk usage

Code:
df

Show directory space usage

Code:
du

Show memory and swap usage

Code:
free

Clear the terminal

Code:
CTRL L

Show content of file

Code:
cat <fileName>

Logout

Code:
CTRL D

Go up/down the terminal

Code:
SHIFT Page Up/Down

From the top

Code:
head

Cursor to start of line

Code:
CTRL A

Cursor the end of line

Code:
CTRL E

Delete left of the cursor

Code:
CTRL U

From the bottom

Code:
tail

Delete right of the cursor

Code:
CTRL K

Delete word on the left

Code:
CTRL W

Paste (after CTRL U,K or W)

Code:
CTRL Y

Create new folder

Code:
mkdir

Auto completion of file or command

Code:
TAB

Reverse search history

Code:
CTRL R

Repeat last command

Code:
!!

List all files and folders <folderName> list files in folder

Code:
ls -a

Detailed list, Human readable

Code:
ls -lh

List jpeg files only

Code:
ls -l *.jpg

Result for file only

Code:
ls -lh <fileName>

Change directory if folder name has spaces use “ “

Code:
cd <folderName>

Go to root

Code:
cd /

Go up one folder, tip: ../../../

Code:
cd ..

Disk usage of folders, human readable

Code:
du -h

Only show disc usage of folders

Code:
du -sh

Print working directory

Code:
pwd

Shows manual (RTFM)

Code:
man <command>

From the top

Code:
head

Sshow content of file

Code:
cat <fileName>

From the bottom -n <oflines> <fileName>

Code:
tail

Create new folder

Code:
mkdir

Copy image to folder

Code:
cp image.jpg <folderName>/

Copy and rename a folder

Code:
cp -R stuff otherStuff

Copy all of *<file type> to folder

Code:
cp *.txt stuff/

Move file to a folder

Code:
mv file.txt Documents/

Move folder in folder

Code:
mv <folderName> <folderName2>

Rename file

Code:
mv filename.txt filename2.txt

Move folder up in hierarchy

Code:
mv <folderName>/ ..

Delete file (s)

Code:
rm <fileName> ..

Ask for confirmation each file

Code:
rm -i <fileName> ..

Force deletion of a file

Code:
rm -f <fileName>

Delete folder

Code:
rm -r <foldername>/

Physical link

Code:
ln file1 file2

Symbolic link

Code:
ln -s file1 file2

List manual pages for subject

Code:
apropos subject

Display man pages containing keyword

Code:
man -k keyword

Show the manual for command

Code:
man command

Make a pdf of a manual page

Code:
man -t man | ps2pdf - > man.pdf

Show full path name of command

Code:
which command

See how long a command takes

Code:
time command

Show possible locations of app

Code:
whereis app

Show which app will be run by default; it shows the full path

Code:
which app

Search for pattern in files

Code:
grep pattern files

Search recursively for pattern in dir

Code:
grep -r pattern dir

Search for pattern in the output of command

Code:
command | grep pattern

Find all instances of file

Code:
locate file

Starting with the root directory, look for the file called filename

Code:
find / -name filename

Starting with the root directory, look for the file containing the string filename

Code:
find / -name ”*filename*” –

Find a file called filename using the locate command; this assumes you
have already used the command updatedb (see next)

Code:
locate filename

Create or update the database of files on all file systems attached to the Linux root directory

Code:
updatedb

Show the subdirectory containing the executable file called filename

Code:
which filename

Starting with the directory called dir, look for and list all files containing TextStringToFind

Code:
grep TextStringToFind /dir –

Change the permissions of file to octal, which can be found separately for user, group, and world by adding: 4 – read ®, 2 – write (w), 1 – execute (x)
Examples:
chmod 777 – read, write, execute for all
chmod 755 – rwx for owner, rx for group and world
For more options, see man chmod.

Code:
chmod octal file

Connect to host as user

Code:
ssh user@host

Connect to host on port port as user

Code:
ssh -p port user@host

Add your key to host for user to enable a keyed or passwordless login

Code:
ssh-copy-id user@host

List IP addresses for all devices on the local machine

Code:
ifconfig

Ping host and output results

Code:
ping host

Get whois information for domain

Code:
whois domain

Get DNS information for domain

Code:
dig domain

Reverse lookup host

Code:
dig -x host

Download file

Code:
wget file

Continue a stopped download

Code:
wget -c file[/code+


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Create a new user call accountname
[code]adduser accountname

Give accountname a new password

Code:
passwd accountname

Code:
su

Stop being superuser and revert to normal user

Code:
exit

Display your currently active processes

Code:
ps

Display all running processes

Code:
top

Kill process id pid

Code:
kill pid

Kill all processes named proc (use with extreme caution)

Code:
killall proc

Lists stopped or background jobs; resume a stopped job in the background

Code:
bg

Brings the most recent job to foreground

Code:
fg

Brings job n to the foreground

Code:
fg n

Installation from source

Code:
./configure
make
make install

install a DEB package (Debian / Ubuntu / Linux Mint)

Code:
dpkg -i pkg.deb

install a RPM package (Red Hat / Fedora)

Code:
rpm -Uvh pkg.rpm

(YUM) Yellowdog Updater Modified

Install the specified packages

Code:
yum install {package-name-1} {package-name-2}
Install package called httpd:
yum install httpd

Remove / Uninstall the specified packages
Remove package called httpd, enter:

Code:
yum remove {package-name-1} {package-name-2}
yum remove httpd

Display the list of available packages

Code:
yum list all

Display list of group software

Code:
yum grouplist

Display list of updated software

Code:
yum list updates

List all installed packages

Code:
rpm -qa
yum list installed

Find out if httpd package installed or not:

Code:
rpm -qa | grep httpd*
yum list installed httpd

Check for and update specified package

Code:
yum update {package-name}

To check for and update httpd package

Code:
yum update httpd

Finding packages containing missing dependencies when installing software from source

Code:
yum whatprovides */<dependencyName>

Pacman

Lists all installed packages

Code:
pacman -Q

Install packages (from file)

Code:
pacman -U

Updates the list of packages and installs a given
package (from repository)

Code:
pacman -Sy

Update packages installed on your system with
the latest versions in the archives

Code:
pacman -Su

Updates the list of packages and upgrade
the packages installed on the system

Code:
pacman -Syu

Remove a package

Code:
pacman -Rc

Remove a package, delete the configuration
files and eliminates the dependencies

Code:
pacman -Rsn

Delete orphaned packages

Code:
pacman -Rs $(pacman -Qqtd)

Try searching within the package database

Code:
pacman -Ss

Show the detailed information on a given package

Code:
pacman -Si

Clear the system cache of video packets

Code:
pacman -Sc

Shutdown the system now and do not reboot

Code:
shutdown -h now

Stop all processes - same as above

Code:
halt

Shutdown the system in 5 minutes and reboot

Code:
shutdown -r 5

Shutdown the system now and reboot

Code:
shutdown -r now

Stop all processes and then reboot - same as above

Code:
reboot

Start the X system

Code:
startx

I hope I learned something new to you. :>
Share it but don't forget to give credits.

- dR.0xYw0Rm aka Gaara