Learn important information about Linux ( with command )

History of Linux

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.

1980- Berkeley Software Development (a part of research program of Berkeley University)

launches open BSD (a small program written in a single floppy).

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- RedHat Company (collection of Linux Sets) came into existence.

99 % servers of Linux till 2012.

LINUX PRINCIPLE

1. Everything is a file.

2. Small, single purpose programmers’

3. Ability to Chain programmers’

4. Avoid captive user interfaces.

5. Configuration data stored in text.

Linux Directory Structure

/home                  Users home (all users folders)

/bin                      Commands (user executable & Scripts)

/usr/bin                Commands (user executable & Scripts)

/sbin                     root privileged command

/usr/local/bin         commands which we make for our use.

/etc                      System Configuration files

/boot                   Linux Kernel & Bootable files

/root                    root (Admin) Data

/mnt                    for mounting any external devices

/dev                    devices (hdd, CD-Rom, Pen Drive)

/srv                     Server data

/sys                     System Information

/lib                       Library files stored

/proc                   virtual file system

/tmp                    Temporary files

/var                      Variable file (database,logs)

/opt                      Add on Application  software

Linux Basic Commands

Directory commands:

·        mkdir – For creating directory.

·        cd – change directory.

·        cd .. – to come out from working directory.

·        rmdir – to remove directory

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.

Commands for deleting:

·        rm filename – deletes a file.

·        rm -i – deletes file/folder in interactive mode (asking mode)

·        rm -r – deletes directory.

·        rm -f – deletes files/folders forcefully.

Help Commands:

·        whatis <command> These all are the help commands. Prints all related tags

·        man <command> about that command.

·        info <command>

·        <command> –help

·        which <command>

·        cd /usr/share/doc

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.

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

Editors in linux:

·       nano

·       vi These editors are used in console mode.

·       vim

·       gvim

·       gedit These editors are used in graphical mode.

·       Emacs

VI editor/ VIM editor:

There are three modes in vi editors

1. ex mode (default mode, by pressing escape key, this mode is used for saving and exit )

2. Insert mode (by pressing insert or I key, this mode is used for editing)

3. Replace mode (this mode is used for replacing text written, by again pressing insert or r key)

For saving document- come on esc mode and write :wq

For setting line numbers in document come on esc mode and write : se nu

For coming on any specific line press line no. and then ‘G’ (ex- 102 then G) or :line no (enter)

For going at the end of page press ‘G’

For going at the top of page press gg

For searching any text in the file /text

For undo u and for redo ctrl+r

Vim editor is not installed default when you install linux, you have to install vim editor. It is the

enhanced version of vi editor.

# vim/vi filename

Press ‘v’ to come to visual mode, here we can select the matter which we want to copy , press ‘yy’

to copy (y stands for yank). Press ‘p’ to paste that matter.

Press ‘dd’ to delete a particular line where cursor is.

Nano Editor:

Nano is a command based editor, earlier used when advanced editors were not came into being.

When you open a a file with this editor, you will find all related help of this command.

SOME BASIC COMMANDS

·       # poweroff -f

·       # halt -n -p – These commands are used to turn off computer.

·       # init 0

·       # init 6 – These commands are used to Restart computer.

·       # reboot

·       # startx – Switch from command to graphic.

·       # init 5 – Restarts system from command mode to graphic mode.

·       # history – To see history of recent commands.

·       # history -c – To clear the history of recent commands

·       # cat > /etc/issue – To create logoff scripts.

·       11. # cat > /etc/motd – To create logon scripts.

·       12. # cal yyyy or mm yyyy – To see the calendar of that month & year.

·       13. # bc – Starts basic calculator.

·       14. # whoiam or # w – To know by which user we logged on

·       15. # adduser <username> – To create user

·       16. # passwd <username> – To give password to user.

·       17. # userdel <username> – To delete user.

·       18. # usermod -L <username> – To lock a user account.

·       19. # usermod -U <username> – To unlock a user account.

·       20. # passwd -d <username> – To remove password for a user.

·       21. # cd ~ – Switch directly to users home directory with.

·       22. # head <filename> – To see the top ten lines of a file.

·       23. # head -n 16 <filename> – To see top 16 lines of a file.

·       24. # tail <filename> – To see the bottom ten lines of a file.

·       25. # tail -n 16 <filename> – To see bottom 16 lines of a file.

·       26. # evince <filename.pdf> – To open a pdf file (only on graphical terminal)

·       27. # sort <filename> – Sort file in a-z format.

·       28. # sort -d <filename> – Sort file in dictionary format.

·       29. # sort -r <filename> – Sort file in z-a format.

·       30. # sort -t : -k 3 –n/r/u <filename>- Sort the file according to given delimiter (n=numeric, r= decending, u=removes duplication)