This document summarizes the history and development of Unix and Linux operating systems. It describes how Unix was created in 1969 at Bell Labs by Ken Thompson, Dennis Ritchie and others. Brian Kernighan named the program Unix in 1970. The operating system was later rewritten in C language by Dennis Ritchie. Linux was created by Linus Torvalds in 1991 based on Unix. The document also provides system requirements and descriptions of common Linux commands and file system structure.

2. In 1969, Four programmer Ken Thompson, Dennis Ritchie, Rudd Canady &
Doug McElroy made a program in Bell labs which does not have any name in
year 1969.
Brian Kernighan checked that program & found it is very good software for
client & networking purpose. He gave the name Unix to this program on 1st
January 1970 (epoch time).
First Operating System. That time that program was written in Assembly
language.
In 1972, a programmer Dennis Ritchie started converting this program in C
language. (Also called founder of C language).
1973- Unix in C language.

3. Paul Allen & Bill Gates are the employee of Bell Labs.
In 1981, they both started Microsoft with 9 more candidates & they gave a
programme named Xenix (1980) but it was flopped.
In 1981- Launched MS-DOS 1.0
In 1984- UNIX open source
In 1985- First Graphical Based OS- Win 2.0
In 1991, Linus Benedict Torvalds, B-tech Iind
year Computer Science, 23
years old student of University of Helensiki (Finland) made Kernel (25th
August 1991).
In 1994- Red Hat Company (collection of Linux Sets) came into existence.
96.8 % servers of Linux till 2009.

4. Everything is a file.
Small, single purpose programmes.
Ability to Chain programmes together to perform complex tasks.
Avoid captive user interfaces.
Configuration data stored in text.

5.  CPU
Min- Intel Pentium 4 2.0GHz
Rec- Intel Duel Core 2.0GHz
 RAM
Min- 512MB (Graphical) 384MB (CLI)
Rec- 1GB
 Hard Disk
Min- 4.5GB, Rec- 10GB

6.  4GB RAM – 2GB Swap
 4-16GB RAM- 4GB Swap
 16-64GB RAM- 8GB Swap
 / - Root Partition
 /boot – Boot Partition
 /swap - swap partition
 /home – Home Partition

7.  /home - Users home (all users folders)
 /bin, /usr/bin - Commands (user executable & Scripts)
 /sbin, /usr/sbin - root privileged command
 /usr - User’s Configurations files
 /etc - System Configuration files
 /boot - Linux Kernel & Bootable files
 /root - root (Admin) Data
 /mnt - for mounting any external devices
 /media - for mounting CD/DVD drives
 /dev - devices (HDD, CD-ROM, Pen Drive)
 /var, - Log files
 /proc - Current running system Information
 /sys - System Hardware Files
 /lib - Library files stored – All commands
 /net - Accessing Network File system
 /misc - Files for Auto-Mounting
 /opt - Optional software
 /tmp - Temporary files
 /srv - Server Database

8.  Post LILO (RHEL4)
 Boot Loader
GRUB (RHEL 5)
 Kernel (Vmlinuz)
 initrd (All device file information)
 init (Run Level)

9. Directory commands:
 mkdir <Directory name> - For creating directory.
 cd <Directory name> - change directory.
 cd .. - to come out from working directory.
 rmdir <Directory name> - to remove directory

10. File Commands:
 touch <filename> - creates a blank file.
 cat > filename - creates a file and for saving this file (ctrl + D)
 cat - to see the content of the file.
 cat file1 >> file2 - to move file1 matter in file2
 cat -n filename - to see how many lines are written in that file.

11. Commands for deleting:
 rm filename - deletes a file.
 rm -i - deletes file/folder in interactive mode (asking mode)

12. Help Commands:
 whatis <command>
man <command>
 info <command>
 <command> --help
 which <command>
 cd /usr/share/doc
These Commands are used as help commands.
Print all tags and summary of the asked command.

13. Copy:
 cp <source> <destination> - copies files from source to destination
 cp -i <source> <destination> - copies files from source to destination in asking
mode
 cp -i * <destination> - copies current working directory all data to
destination.
 cp -r <directory name> <destination> - copies directory from source to
destination

14. Rename & Move:
mv <oldfile> <newfile> (Rename)
mv <filename> <where we have to move the file> (Move)
Listing Commands:
 ls - listing files/folders
 ls -l (ll) - long listing of files/folders with whole information
 ls -a - lists all files/folders (hidden also)
 ls ??? - all files/folders named with 3 characters
 ls m* - files & directories started with letter m.

15.  poweroff -f
 halt -n -p - We can turn off our system by these
commands
 init 0
 init 6 - We can Restart our system by these
commands
 reboot
 startx - Switch from command to graphic.
 init 5 - Restart System graphically.
 history - To see history of recent commands.
 history -c - To clear the history of recent commands
 bc - Starts basic calculator.
 whoami or w - To know by which user we logged on

16.  mkfs.vfat -I /dev/device id - To format device in fat format
 look <word> - For looking the exact word spelling.
 date mmddhhmmyy - To set date.
 uname - To see kernel name.
 uname –r - Kernel release.
 uname –a - Whole information about kernel.
 file <file/directory name> - To check whether it is file or folder.
 cat > /etc/issue - To create logoff scripts.
 cat > /etc/motd - To create logon scripts.
 cal yyyy or mm yyyy - shows calendar of that month & year.

17.  adduser <username> - To create user
 passwd <username> - To give password to user.
 userdel (-r) <username> - To delete user.
 groupadd <name> - To add a group.
 usermod -G <group> <user> - It will add user to group.
 groupdel <name> - To delete group.
 chage -E YYYY-MM-DD <user> - Set user expiration.
 chage -l <username> - To see user detailed information.
 chage -W 1 <username> - To set warning period for user.
 usermod -L <username> - To lock a user account.
 usermod -U <username> - To unlock a user account.
 passwd -d <username> - To remove password for a user.

18. _ _ _ _ _ _ _ _ _ _ owner group filename
f/d User group others
r=4 (22
) w=2 (21
) x=1 (20
)
read write execute
For directory maximum permission = 777
For files maximum permission = 666
Default permission for file = 644
Default permission for directory = 755

19. To give user full permission
 chmod 777 filename
To see the internal permission
 umask (max per. - umask = default permission)
 umask 000 (full permission for all)
 umask 777 (deny for all)
To change the owner of files or directory-
 chown <username> file/directory name
To change group of files & directory-
 chgrp <groupname> file/directory name

20. Commands for setting permission on a single user:
setfacl -m u:<user>:rwx /ww
It will set the full user permission on ww directory.
 getfacl <filename>
It will display full information about that file or directory.
Every user has its own UID (User Identification)
Every group has its own GID (Group Identification)
If UID matches (i.e. login user & owner) user permission is applicable.
If GID matches (i.e. login user & group) group permission is applicable.
If nothing matches other permission is applicable.

21. Files where UID & GID information saved:
/etc/passwd (UID)
/etc/shadow (UID in encrypted form)
/etc/group (GID)
/etc/gshadow (GID in encrypted form)