• clear
    • Clear the screen
  • mkdir 'folder name'
    • Create a directory
  • mkdir -p 'folders name'
    • If you want to create more and more empty directory like: movie >> english >> video
    • Ex. mkdir -p /movie/english/video    
      • Note1: This folders are created in root directory so you have to need root permission so type sudo before mkdir )
      • Note2: if you want to create this folder in other location for example in home directory. (mkdir -p /home/firoj/movie/english/video)  (Note: firoj is my username)
  • rmdir 'folder name'
    • remove directory.
  • rmdir -p 'folders name'
    • After creating multiple empty folder by using mkdir -p, then next step is how to remove it. Using rmdir command you cannot delete if the Directory is not empty. 
    • So using rmdir -p command you can delete all folder and sub-folders.
    • Ex. rmdir -p /home/firoj/movie/english/video    (Note: firoj is my user name.)
  • gedit 'file name'
    • Create and edit file. Gedit is a graphical text editor.
  • nano 'file name'
    • create and edit file, it is same as gedit.
    • Type something
    • press F3 to save (without exit)
    • Ctrl + X, to save and exit. (press 'Y' for save, 'N' for quit without save.
  • rm 'file name'
    • remove files
  • rm -i 'file name'
    • Prompt before every removal. so that you can prevent yourself from accidentally removing a file.
  • rm -r 'file name'
    • remove folder
  • ls
    • list all files and directory, in column format.
  • ls /directory
    • list all files and folder in the specified directory.
    • Ex. ls /tmp      (It display all files and folder under the tmp directory)
  • ls -l
    • list all files and folder in long format means one file per line. That means it shows details about the file and folder.
  • ls -a
    • lists all files including hidden files.
  • ls -al
    • list all files including hidden files in long format.
  • pwd
    • Display your current directory.
  • cd
    • go to the home directory.
  • cd /etc
    • change to etc directory. using this command you can change directory with specified path.
  • cd ..       (space between cd and ..)
    • go to the parent directory.
  • cd /
    • go to the root directory.
  • cd ~
    • '~' is an alias for home directory. It can be used as a shortcut to your home.
  • cd -
    • go to the previous directory.
    • If you are in home directory and you type this command cd - (output: / ) means go the root directory.
  • head 'file name'
    • Display the first few line of a text file. It is same as cat command but it display only header means first few lines.
  • tail 'file name'
    • It same as head and cat command. But it display last few lines of a text file.
  • cp        (copy one file)
    • Ex. cp test test1    (test & test1 are files)
      • It means copy the test file and paste in same location with new name that is test1.
      • You can paste any where.
  • cp /home/firoj/filename /tmp                (copy to another directory)
    • copies a file from one location to another.
    • Note: To move other directory it shows the error 'permission denied'. so type sudo command before cp command.
    • sudo cp /home/firoj/filename /tmp            ('firoj' is  the user name of my computer)
  • cp -r            (copy whole directory)
    • using this command you can copy a folder and its sub-folder.
    • Ex. cp -r /home/firoj/Desktop/test /home
      • It means, copy a test folder from Desktop and paste in home Directory. you can use (~) symbol instead of /home.
  •   Copy Multiple file to Directory
    • Ex. cp test test1 /home/firoj/'foldername'
      • Here test and test1 are two file. I copied from Desktop and paste in specific directory.
  • cp -i
    • to prevent overwriting
  • mv /home/firoj/filename /tmp
    • This command is use to move a file to a new location or to rename files.
    • To rename: mv /home/firoj/test /home/firoj/test2
    • Note: firoj is my user name,   test is the file name.
  • man 'command'
    • This command helps to find the information about a particular command. man means manual pages, known as 'man pages'.
    • Example_1: man cp     (get help on the cp command) 
    • Example_2: man ls
  • whatis
    • To see the description.
    • Ex. whatis cp     (Output: copy file and directories)
    • Ex. whatis ls       (Output: list directories content)
  • whereis
    • Locates the program, source code, and manual page for a command.
    • Ex. whereis ls      (output: ls: /bin/ls  /user/share/man/man1/ls.1.gz
  • which
    • shows the full path of shell commands.
    •  Ex. which cp       (output: /bin/cp)
  • file
    • Linux does not use extensions to determine the file type so this command is use the determine the file type
    • Ex. file data     (data is a text file name)
      • Output: ASCII text
  • touch 'file name'
    • Create an empty file
  • cat 'file name'
    • show the content of a text file on screen.
  • cat -n 'file name'
    • Show content file, with line numbers.
  • cat > 'file name'
    • you can create file using cat > command.
    • Note: press Ctrl + D to save and exit. Ctrl+d means it will send an EOF (End of File) to the running process to ending the cat command.
  • Custom End Maker for cat
    • you can choose an end maker for cat with <<.
    • Ex. cat > 'file name' << end
      • When you type end and press enter, it end the process and save document.
  • cat test > test1               (copy file using cat)
    • It means copy test file and paste it in same location with new file that is test1.
  • tac
    • tac is the backward of cat
    • EX.   i) create a file as a name 'test' and write: 
              • one
              • two
              • three
      • type cat command, cat test
          • output: 
            • one
            • two
            • three
      • type tac command, tac test
          • output:
            • three
            • two
            • one


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