Month: November 2006

History of UNIX

History of UNIX

In mid-1960, When American Telephone and Telegraph ( AT&T), Honeywell, General Electrical (GE) and Massachusetts Institute of Technology (MIT) embarked on massive project to delevelop an information utility. The project call MULTICS ( MULtiplexed Information and Computer Services) which was funded by DARPA ( DoD Advanced Research Project Agency).

In 1969 the MIT and AT&T decided to pull out of MULTICS project. After that Ken Thompson and Dennis Ritchie ( founder of C/C++) who were also part of MULTICS started work on new computer system (OS) based on MULTICS. They decided to call it as “UNIX“. During this time MULTICS project was continuing in Cambridge and which was coninued more than one & half decade.

In 1973, Ken Thompson rewrote most of UNIX in Ritchie’s newly invented C language. During 1978 the University of California had paid $400 to purchase UNIX with source code. Two graduate students Bill Joy and Chuck Haley of Berkeley started making significant modifcation and over the years it developed as independent computer system based on UNIX. They distributed modified UNIX as Berkeley Software Distribution (BSD). Due to licensing limitation Berkeley released modified UNIX as BSD 4.2. UNIX was trademark of AT&T and OS right at that time. They were worried about BSD UNIX popularity.

In this way the Industry was beset by two competing versions of UNIX.

  • AT&T UNIX system-V
  • Berkeley BSD 4.2

Thank you ,

Arun & Yogesh

sudo -configuration

sudo -configuration

1] Introduction:

root is super user with unrestricted access to all system resources and files in Linux OS. The uid and gid of root user is 0 (zero). But many time the system/Linux admin wants to give some restricted access to some user or groups of user. In such case the sudo is the best technique to do this….

sudo utility allows users defined in the /etc/sudoers configuration file to have temporary access to run commands. Normally they would not able to do it, due to file permission restrictions. The commands can be run as user “root” or as any other user defined in the /etc/sudoers configuration file.

All commands run as sudo are logged in the log file /var/log/messages.

2] Sudo configuration file/etc/sudoers

/etc/sudoers file contains all the configuration and permission parameters needed for sudo to work. There are a number of guidelines that need to be followed when editing it with visudo.

Format of sudo file is as below…

user_names/group_name servername = (usernames command can be run as) command

3] How to open sudo file.. /etc/sudoers

Always use visudo command to open /etc/sudoers file visudo

4] How to permit few user to start/restart/stop apache server.

* open sudore file by using above command

# access to Apache2 and MySQL to webgroup group with out password

%webgroup ALL= NOPASSWD: /etc/init.d/apache2

%webgroup ALL= NOPASSWD: /etc/init.d/mysql restart

web ALL= NOPASSWD: /etc/init.d/apache2

* In above example the users in group webgroup can only restart MySQL, they can’t stop or start MySQL service.

# access to Apache2 with password to user webuser

webuser ALL= /etc/init.d/apache2

# Members of the myroot group may gain root privileges

%myroot ALL=(ALL) ALL

4] How to use sudo$ sudo /etc/init.d/apache2 restart
* Forcing reload of apache 2.0 web server… [ ok ]$

** Here in below example the webuser need to enter his password to very that ‘webuser’ is authentic user.$ sudo /etc/init.d/apache2 restart
* Forcing reload of apache 2.0 web server… [ ok ]$