How to use Oracle VM Virtual Box

Here the snapshots of using a Oracle VM Virtual Box for installing Red hat linux(or any other Os) in sequence order are there. please save this image and follow the steps.Now Installation of Red hat Linux

Some Linux Commands

Date and time

  • date (show system date)
  • cal 9 1751( show calendar)
  • date mmddhhmmssyy ( set date & time)
  • date 12051145302008


  • find / -name sam.txt (find a file)
  • find / -iname sam.txt (search with capital & small)
  • find / -size 1 mb (find files with 1 mb size)
  • find / -size +1mb (find files > then 1 mb)
  • find / -size -1 mb (find files <then 1 mb)
  • find / -usr marc (find  user marc,s files )
  • find / home –user marc (find user march in home )
  • stat /data/sam.txt (displays file properties)
  • touch /data/sam.txt (update the time)
  • touch logitech
  • find / -atime +10
  • find / – atime -10
  • find / -mtime +10
  • find / -mtime -10
  • find / -name india.txt –not –user mann
  • find / -name kashmir.txt –not user root
  • find / -name india.txt –not –size -10mb
  • find / -name india.txt –and –user mann –not –size +10mb

Linux – File And directories

  • rm abc  (can remove a file)
  • mkdir abc (create a directory)
  • rmdir abc (remove an empty directory)
  • rm –r abc (delete directory recursively)
  • mkdir /data (create a directory)
  • mkdir /data/abc (create sub directory)
  • pwd (print working directory)
  • cd /data ( change the directory)
  • cd (change to home directory)
  • cd / (change to / directory)
  • cd .. (come back one directory)
  • cd – ( back to previous directory)
  • tree /root ( to display directory structure)
  • rm –rf  abc ( to delete a directory forcefully & recursively)
  • ls (list of files and folders in current directory)
  • ls –l (long listing of files & folders)
  • ls –a (list all with hidden files & folders)
  • ls /  (list files & folders )
  • ls /abc/xyz (will list subdirectories)
  • cp –rvf /abc/xyz  (copy recursively)
  • ls *.txt (list .txt files)
  • history (displays last inserted commands)
  • !10 (run number 10th command)
  • !cal (run last command started with cal)
  • history –c (Clear all history)
  • man/info date (manual files)
  • makewhatis (creates what is database)
  • whatis cal (displays use of cal command)
  • cal > abc ( send output of cal  to file abc)
  • date >> abc (append to abc file)
  • more sales.txt (displays page contents page wise)
  • history | more (displays history page wise)
  • history | less (———— can up and down)
  • history | tail -20 ( displays last 20 inserted lines)
  • History > history.txt (send history to a file)
  • tr ‘a-d ‘ ‘A-D’ < sam.txt ( display small to capital)
  • tr ‘A-D ‘a-d’ < sam.txt (displays capital to small)

Text Editor in Linux

  • The vi or vim editor can be used to create edit a file in Linux operating system. And it has three modes.
  • 1) cmd mode : File editing commands like copy, paste, search, replace, delete
  • 2)Insert mode: It can be used to insert text or delete text in a file.
  • 3)ex mode : Exit mode is used to save the text in a file and can be used to quit from a file.
  •        vi abc           ( can  create a file)

Press  I                     ( to insert text in a file)

Press  esc                (to come back to cmd mode)

Press  esc                (to ex mode)

Press  :w                  (to save text in a file)

Press  :q                  (to quit from a file)

Press  :wq              (to save & quit from a file)

Press  :q!                to forcefully quit without saving

Press  :wq!             To forcefully quit & save a file

Press  :u                  to undo last changes

Press  :abc             (to search abc from a file)

Press   yy               to copy a line

Press  p                   to paste

Press  dd                to delete a line

Press  5 dd            to delete 5 lines

Press  5yy             to copy 5 lines

Press  ctrl + r       to redo

Press   o                  to insert a line down

Press  shift + o     to insert a line at up

Press shift + g      to insert a cursor at end of the last line

Press shift + m    to put  cursor in middle of  screen

Press shift+h       to put cursor top of the screen

Press yw                to copy a word

Press yc                 to copy a character

Press  dw               to delete a particular word

Press 5+ dw          to delete no of words

  • cat > abc (create a file ctlr+d to save)
  • cat abc  (displays the contents of a file)
  • cp /abc  /root/abc (copy a file)
  • mv abc appin (rename a command)
  • mv appin /root (can move a file)
  • cat >> abc (append to a file)

What is Boot loader and GRUB

Boot loader is the first software program that runs when a computer starts. It is responsible for loading and transferring control to the operating system kernel software. The kernel, in turn, initializes the rest of the operating system

GRUB (GRand Unified Bootloader), which is installed by default, is a very powerful boot loader. GRUB can load a variety of free operating systems, as well as proprietary operating systems with chain-loading (the mechanism for loading unsupported operating systems, such as DOS or Windows, by loading another boot loader).



  • Linus Torvalds
  • Finish college student in 1991
  • Created Linux kernel
  • When Linux kernel combined with GNU applications, complete free UNIX-like OS possible
  • Linus  Torvalds announced Linux in the comp.os.minix newsgroup in august 1991.

Why Linux

  • Fresh implementation of UNIX APPIs
  • Open source development model
  • Supports wide variety of hardware
  • Supports many networking protocols and configuration
  • Fully supported


  • Linux is a UNIX-like OS: Linux is as similar to UNIX as the various versions are to each other. Conceptually, anything that can be done with another version of UNIX can be done with Linux operating system, although the means may vary slightly.
  • Multi-user and multi-tasking: Linux is a multi-user and multi-tasking operating system. That means more than one person can be logged on to the same Linux computer at the same time. And a user can have more than one process executing at the same time.
  • Wide hardware support: RedHat Linux supports most  pieces of modern x86-compatible hardware. In the early days of Linux hardware support was limited: today Linux support has become a check list for hardware vendors.
  • Fully supported: Red Hat is fully supported distribution.