Why Linux

Already we have seen what is meant by Linux.
Now friends we will see why Linux. 

  • It is open source development model.
  • It supports wide variety of hardware.
  • It supports many networking protocols and configurations.
  • Red Hat Linux is fully supported distribution. Red Hat Inc. provides many support programs for the smallest to the largest companies. 

Local Logins:
Access to system requires authentication. The most common method used to authenticate
A user is a “login” process. Linux provides “text-based” and “graphical” login.
When you enter both username and password correctly then you will be logged in.
If you r system is text-based, you will have a command prompt, probably in dollar sign ($).
For example. 

localhost login : shri
Password: ******
Last login: Mon Dec 23 19:30:46 On: 0
[shri@localhost shri]$ 

 On systems that boot directly into the X window system, what you see depends on the display manager being used.
The default manager for Red Hat Linux is gdm(GNOME Display Manager). 

Virtual Consoles:
  
Multiple non-GUI logins are possible through the use of virtual consoles.
There are by default 6 available virtual consoles.
These are available through ctrl-alt-F[1-6]
If X is running ,it is available as
Ctrl-alt-F7

 Now I will give you some information about directories .

  /bin - essential UNIX commands such as ls, etc. Should contain all binaries needed to boot the system or run it in single-user mode                                

  •  /boot - files used during booting and possibly the kernel itself are stored here
  •   /dev - contains device files for various devices on system
  •   /etc - files used by subsystems such as networking, NFS, and mail. Includes tables of disks to mount, processes to run on startup, etc.
  •   /etc/rc.d - contains a number of shell scripts that are run on bootup at different run levels. There is also typically an rc.inet1 script to set up networking (in Slackwar), an rc.modules script to load modular device drivers, and an rc.local script that can be edited to run commands desired by the administrator, along the lines of autoexec.bat in DOS.
  •   /etc/rc.d/init.d - contains most of the initialization scripts themselves on an rpm-based system.
  • /etc/rc.d/rc*.d - where ``*'' is a number corresponding to the default run level. Contains files for services to be started and stopped at that run level. On rpm-based systems, these files are symbolic links to the initialization scripts themselves, which are in /etc/rc.d/init.d.
  •   /etc/skel - directory containing several example or skeleton initialization shells. Often contains subdirectories and files used to populate a new user's home directory.
  •   /etc/X11 - configuration files for the X Window system
  •   /home - home directories of individual users
  •   /lib - standard shared library files
  •   /lib/modules - modular device driver files, most with .o extensions
  •   /mnt - typical mount point for many user-mountable devices such as floppy drives, cd-rom readers, etc. Each device is mounted on a subdirectory of /mnt.
  •   /proc - virtual file system that provides a number of system statistics
  •   /root - home directory for root
  •   /tmp - directory specifically designed for programs and users to store temporary files.
  •   /usr - directory containing a number of subdirectory with programs, libraries, documentation, etc.
  • /usr/man - location of manual page files.
  • /var/spool - temporary storage for files being printed, mail that has not yet been picked up, etc.

   Commands:
Now we will see some useful commands.

 cal - displays a 12-month calendar for the given year or a one-month calendar of the given month

  • usage: cal month year
      • cal 9 2002
      • it will show the calendar of sept 2002.
      • Now you try to display calendar of sept 1752.
        •  date - displays or sets date and time
  •  usage: date
  •   cd - change working directory. This is a shell builtin in bash
  •   cdplay - command line utility for playing audio cds.
  •    mkdir - create a directory.

       Usage: mkdir student  here student is diretory name