CHMOD Linux Command (octal mode)

What is CHMOD ?
chmod is a way to change permission of file or directory in linux. with this command we can get more access to file or directory.


Permission is mean : read, write and execute (r w x)

syntax :

chmod options permissions filename

The distribution of access rights.

There are 3 digits, each digit represents the permissions of the file.
as an example, consider the following three lines of the file and note the first line of the blue:

 drwxr-xr-x   2   root root     4096 Nov  5 20:48 cdebconf
-rw-------         1   root root 107916 Nov  5 20:48 partman
-rw-r--r--        1   root root   68631 Nov  5 20:48 status

The blue letters are made up of 10 letters, we count on the leftmost line, the first letter 'd' symbolizes the directory, the letter 2 to 4 symbolizes the user rights, letter 5 to 7 symbolizes the right group, and 8 to 10 letters symbolize the rights of other.

 drwxr-xr-x   2   root root     4096 Nov  5 20:48 cdebconf
 12345678910
 
then we broke into three groups (user, group, and other), each group has 3 letters, note the following line:

 d    rwx     r-x    r-x        2   root root     4096 Nov  5 20:48 cdebconf
  1    2 3 4    5 6 7    8910
       user    group     other



the use of numbers in octal mode.
the highest number in the octal mode are 7 and the lowest number is 0.
figure 7 we divide into 4 groups of numbers, ie numbers 4,2,1 and 0, or in other words the number 7 is the sum of the numbers 4 + 2 + 1 + 0.


number 4 means 'read'
number 2 means 'write'
number 1 means 'execute'
number 0 mean 'none or no permission'
 
Example calculation:

chmod 754 filename

to simplify the calculations it will be my like into 3 groups: the first group with the number 7 is the right user, the second group with the number 5 is the right group, while the third group is the number 4 is the right of.

chmod 754 filename
chmod        7                             5                      4                           filename
                4+2+1                          4+0+1                      4+0+0
        read+write+execute      read+no write+execute    read+no write+no execute
                 user                                group                        other 


so with the explanation, the numbers 754 mean the folder has permissions for the user is a full access (read,write, execute) permissions, to the group have read and execute, while the other only has read access rights.

 conclusion :

drwxr-xr--  is equal to 754
 

DEBIAN 7.2 INSTALLATION (Desktop Version)

BASIC

In This Tutorial, i use AMD Phenom(tm) II X2 555 Processor, 2 Gb Of Ram, 500 Gb Hardisk, 2 NIC and 1 Wifi Addapter attached to my PC.

Now get the Debian 7.2 x64 DVD 1by visit http://repo.ugm.ac.id/iso/debian/7.2.0/amd64/iso-dvd/debian-7.2.0-amd64-DVD-1.iso

After finish download, burn it or use usb flasdisk to boot from. in this tutor i burn it and boot with my DVD-Room.

LETS START

Set your PC to boot from DVD-Room, put your DVD Debian 7.2 into DVD-Room, restart PC.

Select Graphical Install

In the Language Option, select your language (English)

 Location option, select your location (Indonesia)

Locales option, select your locales (United States)

Keyboard option, select your keyboard (American English)

System will detect your installer commponent from DVD.

Network option, select your ethernet as primary (eth0).

System will detect DHCP Server if you have server connect to PC, if you haven't, system will show this picture, and select Continue.

Network Configuration option, select Configure network manually, and starting input IP Address etc.

Hostname option, input your hostname (stemsa)

Input your Domain name (stemsa.net)

Setup users and passwor, input your passwor as root.

Input new user and password.
this new user have limited access as user reguler and doesn't have administrator right, so input a diferent password from root.

Configure the clock option, select your time zone (Western)

Partition disk option, in this option i choose automatic partition. It will let system to partition the disk with default hardware you have. so i select Guided - use entire disk.

Installing base system, it will take couple minut.

Configure package manager option, select No, so system will not scan another DVD, because i only have DVD1.
If you have other DVD like DVD 2 to 4, you just put in DVD-Room and system will scan it one by one until last DVD. This option use for additional package installation in the future.

Network mirror option, select No, because i won't mirror.

Participate in the package usage survey, slect No.

Software select option, select Debian desktop environment and Standard system utilities.

Select and install software, be patient it's take more time.

Install GRUB loader, select Yes.

DVD-Room will automatically eject, take out DVD1. system reboot.
Enjoy.

DEBIAN LINUX 7.2

DEBIAN 7.2 SERVER or DESKTOP ?

What is Debian ?
Debian is an all-volunteer organization dedicated to developing free software and promoting the ideals of the Free Software community. The Debian Project began in 1993, when Ian Murdock issued an open invitation to software developers to contribute to a complete and coherent software distribution based on the relatively new Linux kernel. That relatively small band of dedicated enthusiasts, originally funded by the Free Software Foundation and influenced by the GNU philosophy, has grown over the years into an organization of around 951 Debian Developers.

Minimum Hardware Requirements !
It's have two optional for your installation, when you need graphical interfaces or if you just wont use it for server or CLI (command line interface).
here is the minimum requirenment.
For No Desktop :
Need minimum Ram 64 megabytes and Hardisk 1 gigabyte, and its also recomended that you have to got 256 megabytes of Ram.
For Desktop :
Need minimum 128 megabytes (512 megabytes of Ram recomended)  and 5 gigabyte Hardisk.