Introduction to Unix \ Linux

Unix \ Linux Introduction for Begineers

What is UNIX?

Unix is an Operating System
It is truly the base of all Operating Systems
Sub-products of Unix are Linux, Ubuntu, Solaris, POSIX, etc.
It was developed in the 1970s by Ken Thompson, Dennis Ritchie, and others in the AT&T Laboratories.
It was originally meant for programmers developing software rather than non-programmers.

The lowest level is the kernel , which schedules tasks , manages resources, and controls security.
The next level is the shell, which acts as the user interface, interpreting user commands and starting applications.
The highest level is utilities, which provides utility functions. It is called as USER level.

/: This is top level directory It is parent directory for all other directories It is called as ROOT directory It is represented by forward slash (/) C:\ of windows
/root: it is home directory for root user (super user) It provides working environment for root user C:\Documents and Settings\Administrator
/home: It is home directory for other users It provide working environment for other users (other than root) c:\Documents and Settings\username
/boot: It contains bootable files for Linux Like vmlinuz (kernel)..... ntoskrnl Initrd (INITial Ram Disk)and GRUB (GRand Unified Boot loader).... boot.ini, ntldr
/etc: It contains all configuration files Like /etc/passwd..... User info

/etc/resolv.conf... Preferred DNS
/etc/dhcpd.conf.... DHCP server C:\windows\system32\dirvers\/usr By default soft wares are installed in /usr directory (UNIX Sharable Resources) c:\program files

/opt: It is optional directory for /usr It contains third party softwares c:\program files
/bin: it contains commands used by all users (Binary files)
/sbin: it contains commands used by only Super User (root)
/dev: it contains device files Like /dev/hda ... for hard disk /dev/cd rom ... for cd rom Similar to device manager of windows
/proc: it contain process files Its contents are not permanent, they keep changing It is also called as Virtual Directory Its file contain useful information used by OS like /proc/meminfo ... information of RAM/SWAP /proc/cpuinfo ... information of CPU
/var: it is containing variable data like mails, log files /mnt it is default mount point for any partition It is empty by default
/media: It contains all of removable media like CD-ROM, pen drive
/lib: It contains library files which are used by OS It is similar to dll files of windows Library files in Linux are SO (shared object) files