GE 2155 Computer practice laboratory II - BASIC UNIX COMMANDS

                             I  BASIC  UNIX  COMMANDS

UNIX  COMMANDS

General Purpose commands:

1. cal

The cal command is used to display the specified month or year calendar.

Syntax: 

$cal month or year

Example: 

$cal 2010

It displays  the calender for the entire year.

2.    Date

The date command is used to display the current date, day of the week, month,

day, time and year.

Syntax: 

$date

Output:

Mon   Mar 30  3:45:30     2010

3.   Echo

The Echo command is used to print the message on the screen.

Syntax:

$echo message

Example: 

$echo Computer practice lab-II

          

Output:

 Computer practice lab-II

4. who command

   This is used to display the data about all the users currently logged into the system.

Syntax:

      $who

Output:

     User1  tty1     Mar 30     09:30

     User2  tty2     Mar 30     09:40

5.  who am i

 It displays the login details pertaining to the user.

 Syntax:

 $who am I

 Output:

 User1    tty1   Mar 30   09:30

   

6. id command

          It is used to display the numerical value corresponds to the login name, user-id and group-id.

Syntax:

  $id

Output:

Uid=514(user1)   gid=538(group)

7. tty

The tty command  is used to know the terminal name that we are using.

Syntax:

    $tty

Output:

   dev/tty1

8.   clear command

                It is used to clear the screen and will place the $ prompt at the top left corner on the screen.

Syntax:

$clear

Directory Commands

1. mkdir – Make directory

It is used to make a new directory.

Syntax: 

  $mkdir   dir_name

Example:

  $mkdir   turbo

2.  chdir  (or)  cd command

               It is used to move from one directory to another. Before using cd command, the directory has to be created using mkdir.

Syntax:

$cd dir_name

             

Example:

$cd turbo

3.  pwd – present working directory

  It is used to know the current working directory.

  

Syntax: 

 $pwd

             

Output:

  user/turbo

4. rmdir – remove directory

It is used to remove a directory.

Syntax:

   $rmdir  dir_name

Example:

    $rmdir turbo

File commands:

1. Creating a file:

Cat command is used to create a file.

   

 Syntax:

           $cat>filename

Example

           $cat>sample

  

       Press enter and type the information. After finished typing, press “ctrl+z” to save the Information and terminate.

2. Displaying the content of the file:

   Cat command is used to display the content of the file.

  Syntax:

      $cat filename

  Example:

      $cat sample

            

3. Copying a file:

         Cp command is used to copy the contents of one file to another.

  Syntax:

        $cp  oldfile  newfile

   Example:

         $cp sample sample1

     The contents of  sample are copied into sample1.

4. Removing a file:

    rm command is used to remove  an existing file.

 Syntax:

       $rm filename

 

  Example:

        $rm sample1

5. Moving a file:

    mv command is used to move the contents of one file to another.

 Syntax:

     $mv oldfile newfile

 Example:

     $mv sample sample1

 The contents of sample will be moved to sample1. File sample will be removed.

6. Listing files and directories:

   ls command is used to view the contents of a directory.

 Syntax:

    $ls

7. Counting number of words in a file:

       wc command  is used to display number of lines, words and characters in a file.

Syntax:

     $wc filename

Example:

     $wc sample

Output:

  5  10   45

Sample file contains 5 lines, 10 words and 45 characters.

8. Head command

     It display first 10 lines of a file.

 Syntax:

  $head filename

 Example:

  $head sample

9. Tail command

     It display 10 lines from the end of the file.

   Syntax:

 $tail filename

Example:

 $tail sample

10. Grep command

     It is used to print specified pattern from the file. Grep stands Global regular expression. The entire file is scanned for the required pattern.

    $grep  pattern    filename

11. Uniq command

     It removes duplicate records from the file.

Syntax:

      $Uniq filename

12.  nl command

     nl command adds line number to a file.