GNU/Linux Command Line session (1) :

In GNU/Linux everything is a file ... All configurations have files Using the text mode on GNU/Linux Operating System is pretty light .. The following figure shows how does the system work on your GNU/Linux Operating System ( User - Utility - !Shell - Kernel - Hardware )

We have two types of Terminals :

1. Virtual Terminal ---> cause there is no other machine ( as in figure 2 ) " A mainframe with terminals "

2 -Terminal Emulators ( Psuedo ) ---> from the GUI ( Graphical User Interface )

tty , pts :

try using the command tty from any GUI terminal ( psuedo ) , most propably you'll get something like : /dev/pts1 or /dev/pts now use the terminals through Alt+Ctrl+F1 .... F6

The general form of any command is like :

• command ] [?
• command -option []
• command -option ] [?

[] == argument

$ls -la 

$ls –list

$ls --almost -list

$ls -h

!( h : for human readable )

ls -k is your friend ..

$man -k

What manual page do you want?

usage of man -k is something like :

$man -k kernel

$man -k copy 

$man -k delete 

so you can get use of it when you don't know the specific command to get it's manual directly like

$man cp

( the copying command )

$man mv

( the moving "deleting command - or renaming )

man is the short name of manual and you can use the command info as well which is a documentation browsing system

• ___/
• |
• |___/bin
• |
• |___/boot
• |
• |___/dev
• |
• |___/etc
• |
• |___/home
• |
• |___/initrd
• |
• |___/lib
• |
• |___/lost+found
• |
• |___/media
• |
• |___/mnt
• |
• |___/opt
• |
• |___/proc
• |
• |___/root
• |
• |___/sbin
• |
• |___/srv
• |
• |___/sys
• |
• |___/tmp
• |
• |___/usr
• |
• |___/var

Old School ASCII Graphics ;)

the famous command cd

$cd .. 

" Up "

$cd -  

" Back"

Touch command ..

$touch oct-{first,second,third,fourth}-{1,2,3,4,5,6,7}

$ls oct*

$ls oct-fourth*

for more information about the “ touch “ command

$man touch

;)

cp ( the copying command ) cp OPTION?... SOURCE DEST cp OPTION?... SOURCE... DIRECTORY

$cp -F

( F: Force )

$cp -R

( R: Recursive )

$cp -rf

( recursive and force )

pwd : print working directory

$ pwd

/home/slacker

some other commands you may find it usefull ..

which :

shows the full path of (shell) commands.

$which mozilla

/usr/bin/mozilla

whereis :

whereis locates source/binary and manuals sections for specified files

$whereis mozilla

mozilla: /usr/bin/mozilla /usr/lib/mozilla /usr/local/mozilla /usr/share/man/man1/mozilla.1.bz2

who :

tells who is logged on

whatis :

whatis searches a set of database files containing short descriptions of system commands for keywords and displays the result on the standard output. Only complete word matches are displayed.

$whatis mozilla

mozilla              (1)  - a Web browser for X11 derived from Netscape Communicator

whoami

print efictive userid same as id -un

$whoami

slacker

$id -un

slacker

env print environment values try it on your machine cause the result is long to be copied in here ..

echo : display a line of text

$echo $SHELL

/bin/bash

$echo $PATH

/usr/bin:/bin:/usr/bin:/usr/local/bin:/usr/X11R6/bin/:/usr/games:/home/slacker/bin

$echo GO  $USER

GO  slacker 

;)

$echo DJ KING IS A  $USER

DJ KING IS A  slacker

= )

$echo YOU NEVER KNOW == MohammedSameer

YOU NEVER KNOW == MohammedSameer

GNU/Linux is fun .. isn't it ? ;)

Permissions :

ls -l

you'll find the following for an example :

-rw-r--r--   1      1000 users       366481 Jul 24 19:59 tls1.4.1-linux-x86.tar.gz

drwx------   5 acidtears acidtears     8192 Aug 18 01:32 tmp/

-rw-r--r--   1 acidtears acidtears  4665344 Aug  2 23:41 Usher_vs_Bee_Gees_Stayin_Yeah.mp3

drwxr-xr-x   5 acidtears acidtears       56 Aug 17 08:23 Wireless-NIC/

the first part on the left is called “ Permissions “ 10 charachters can be divided into three sections

for an example : -rw-r—r-- in learning these permissions first of all we must divide them into the 3 parts i have just told you about -|rxw |r-- |r--

1 2 3

the first - means regualar type ( other types such as -d ( directory ) or c ( charachter device )

r : read

w : write

x : execute

1. user ( who has created that file/directory )
2. group
3. anyone else ( others )

in the same example we can notice easily that the user (1) can read (r) , write (w) and execute(x) where the group and others can only read (r)

to change these permissions we use the command line “ chmod “

we can do that using two methods

$chmod u -/+ rwx

$chmod g -/+ rwx

$chmod o -/+ rwx

where (u)ser (g)roup (o)thers

we can change the permissions in an easier way using numerical numbers as i said earlier the attributes are divided into three parts

r w x | r w x | r w x

4 2 1 | 4 2 1 | 4 2 1

say that we have a file that we want to make it readable , writable and executable for the user , !executable by the group , readable and writable for the others

user | group | others

r w x |r w x | r w x

4 2 1 0 0 1 4 2 0

add every section of the 3 and it should give a number of 3 patterns in the end

user = 4+2+1 = 7

group = 0+0+1 = 1

others = 4+2+0 = 6

then simply the command will be

$chmod 716 testfile