BASIC UNIX COMMANDS

Ex. No. :1

BASIC UNIX COMMANDS

AIM:

To implement the basic UNIX commands.

BASIC UNIX COMMANDS:

1. Command:         Who

Syntax                        :  who

Description     : Tells you who's logged on, and where they're coming from.

Example         : who

Output            :          

                 [itstaff@localhost itstaff]$ who

                 itstaff  pts/1        Nov 13 10:21 (192.168.11.87)

                 root     :0           Nov 13 11:36

                 itstaff  pts/2        Nov 13 12:03 (192.168.11.86)

               

     [itstaff@localhost itstaff]$

                Options       : who – [option]

OPTION	DESCRIPTION
-a	Displays UNIX accounting information.
-b	Displays the date an time of the last reboot.
-q	Displays only the login names and the number of users currently logged in.
-r	Displays the  current init level.
-s	Displays the file name and time fields
-u	Displays file name with current information   .  – user is idle or not.

2. Command: date

       

Syntax                        :  date

Description     : Displays the date month and time.

            Example         : date

Output            :

[itstaff@localhost itstaff]$ date

Thu Nov 13 14:54:42 IST 2008

[itstaff@localhost itstaff]$

            Options: date  +%[option]

OPTION	DESCRIPTION
%a	Displays the abbreviated day name
%A	Displays the full day name
%b, %h	Displays the abbreviated month name
%B	Displays the full month name
%c	Displays the current date and time
%C	Displays the centaury as a decimal number
%d	Displays the day of the month
%D	Displays the date in the format mm/dd/yy
%H	Displays the hour(00-23)
%I	Displays the hour(01-12)
%j	Displays the day of the year
%m	Displays the month of the year (01-12)
%M	Displays the minute(00-59)
%n	Inserts a new line character
%p	Displays  A.M/P.M appropriately
%r	Displays the 12 hour clock with  A.M/P.M appropriately

3. Command:      id

Syntax                        :   id

Description     : The id command is used to display the numerical value that corresponds to your login name.

Example         : id

Output            :

[itstaff@localhost itstaff]$ id

uid=539(itstaff) gid=540(itstaff) groups=540(itstaff)

[itstaff@localhost itstaff]$

4. Command: clear   

Syntax                        :   clear

Description     : clears the screen of your terminal.

Example         : clear

Output            :

[itstaff@localhost itstaff]$ clear

[itstaff@localhost itstaff]$

5. Command:  man

Syntax                        : man [UNIX command]

Description     : Gives the complete access to the Unix Manual

Example         : man wc

Output            :

[itstaff@localhost itstaff]$ man wc

WC(1)                                 FSF                                WC(1)

NAME

       wc - print the number of bytes, words, and lines in files

SYNOPSIS

       wc [OPTION]... [FILE]...

DESCRIPTION

       

       Print byte, word, and newline counts for each FILE, and a total line if

       more than one FILE is specified.  With no FILE, or when FILE is -, read

       standard input.

       -c, --bytes

              print the byte counts

       -m, --chars

              print the character counts

       -l, --lines

              print the newline counts

       -L, --max-line-length

              print the length of the longest line

:

6. Command: clear   

Syntax                        :   clear

Description     : clears the screen of your terminal.

Example         : clear

Output            :

[itstaff@localhost itstaff]$ clear

[itstaff@localhost itstaff]$

7. Command:     cal   

Syntax                        :   cal  [month]  [year]

Description     :

Example 1      : cal

Output            :

[itstaff@localhost itstaff]$ cal

   

November 2008

Su Mo Tu We Th Fr Sa

                   1

 2  3  4  5  6  7  8

 9 10 11 12 13 14 15

16 17 18 19 20 21 22

23 24 25 26 27 28 29

30

[itstaff@localhost itstaff]$

DIRECTORY COMMAND:

1.  Command     : mkdir

Syntax                        : mkdir [directory_name]

Description     : Create a new directory in the specified name

Example         : mkdir unix

Output            :

[itstaff@localhost itstaff]$ mkdir kamaraj

[itstaff@localhost itstaff]$

2. Command      : cd

Syntax                        : cd [directory_name]

Description     : Used to change from working directory to another directory

Example         : cd kamaraj

Output            :

[itstaff@localhost itstaff]$ cd kamaraj

[itstaff@localhost kamaraj]$ pwd

/home/itstaff/kamaraj

[itstaff@localhost kamaraj]$

3. Command      : rmdir

Syntax                        : rmdir [directory_name]

Description     : Used to remove the specified directory

Example         : rmdir kamraj

Output            :

[itstaff@localhost itstaff]$ rmdir kamraj

[itstaff@localhost itstaff]$ cd kamraj

-bash: cd: kamraj: No such file or directory

[itstaff@localhost itstaff]$

4. Command      : ls

Syntax                        : ls [option(s)]

Description     : Lists sets or files of current user id or current directory

Example         : ls

Output            :

Options           : ls [option(s)]

5.  Command:  pwd

Syntax                        :   pwd

Description     : Displays the absolute path name of the currtntly working directory.

Example         : pwd

Output            :

[itstaff@localhost itstaff]$ pwd

/home/itstaff

[itstaff@localhost itstaff]$

FILE COMMANDS

1. Command      : cat

Syntax                        : cat [option(s)] [file(s)]

Description     : List the content of the specified file

Example1       : cat  > file.txt [ Creates the file with the specified file name]

Output            :

[itstaff@localhost itstaff]$ cat > file.txt

GE 2155 : Computer Practice Laboratory II

Department of Informatiin Technology

Unix Programming

[itstaff@localhost itstaff]$

Example2       : cat file.txt [List the content of the specified file]

Output            :

[itstaff@localhost itstaff]$ cat file.txt

GE 2155 : Computer Practice Laboratory II

Department of Informatiin Technology

Unix Programming

[itstaff@localhost itstaff]$

            Example 3      : cat –n file.txt [List the content of the specified file with line number]

            Output            :

[itstaff@localhost itstaff]$ cat -n file.txt

     1  GE 2155 : Computer Practice Laboratory II

     2  Department of Informatiin Technology

     3  Unix Programming

[itstaff@localhost itstaff]$

Example 4      : cat file.txt file1.txt >> file2.txt [Appends the file content and stores in file2.txt]

Output            :

[itstaff@localhost itstaff]$ cat file.txt

GE 2155 : Computer Practice Laboratory II

Department of Informatiin Technology

Unix Programming

[itstaff@localhost itstaff]$

[itstaff@localhost itstaff]$ cat file1.txt

CSE

IT

ECE

EIE

PT

EEE

BT

Mech

[itstaff@localhost itstaff]$ cat file.txt file1.txt >> file2.txt

[itstaff@localhost itstaff]$ cat file2.txt

GE 2155 : Computer Practice Laboratory II

Department of Informatiin Technology

Unix Programming

CSE

IT

ECE

EIE

PT

EEE

BT

Mech

[itstaff@localhost itstaff]$

2. Command      : wc

Syntax                        : wc [option(s)] [file(s)]

Description     : Used to count the number of lines, words and characters in a file of a group of file.

Example         : wc file.txt

Output            :

[itstaff@localhost itstaff]$ wc file.txt

      3      13      96 file.txt

[itstaff@localhost itstaff]$

            Options           :

                        -c         Counts number of character in the file

                        -w        Counts number of words in the file

                        -l          Counts number of lines in the file

3. Command      : file

Syntax                        : file [file_name]

Description     : Determines the type of the specified file

Example         : file file.txt

Output            :

[itstaff@localhost itstaff]$ file file.txt

file.txt: ASCII text

[itstaff@localhost itstaff]$

4. Command      : rm

Syntax                        : rm –optiin [file name]

Description     : It deletes the specified file

Example         : rm rfile.txt

Output            :

[itstaff@localhost itstaff]$ cat rfile.txt

file command

directory command

filter command

[itstaff@localhost itstaff]$ rm rfile.txt

[itstaff@localhost itstaff]$ cat rfile.txt

cat: rfile.txt: No such file or directory

[itstaff@localhost itstaff]$

            Option            :

                        -r                     deletes the directory

                        -f                     force remove file

                        -rf                    force remove directory

5. Command      : cp

Syntax                        : cp [source file name] [destinatiin file name]

Description     : Copies source file to destinatiin file

Example         : cp file.txt cpfile.txt

Output            :

[itstaff@localhost itstaff]$ cat cpfile.txt

cat: cpfile.txt: No such file or directory

[itstaff@localhost itstaff]$ cat file.txt

GE 2155 : Computer Practice Laboratory II

Department of Informatiin Technology

Unix Programming

[itstaff@localhost itstaff]$ cp file.txt cpfile.txt

[itstaff@localhost itstaff]$ cat cpfile.txt

GE 2155 : Computer Practice Laboratory II

Department of Informatiin Technology

Unix Programming

[itstaff@localhost itstaff]$

Filter Commands:

1. Command      : head

Syntax                        : head –optiin [file name]

Description     : Writes the first ten line of the file to the screen

Example         : head stringmanip.sh

Output            :

[itstaff@localhost itstaff]$ head stringmanip.sh

stringlen()

{

        len=`echo $1 | wc -c`

        len=`expr $len - 1`

        echo "Length of the given string is $len"

}

stringcopy()

{

        len=`echo $1 | wc -c`

[itstaff@localhost itstaff]$

Optiin [n]        : Says the number of lines to be displayed

Example         : head -5 stringmanip.sh

2. Command      : tail

Syntax                        : tail –optiin [file name]

Description     : Writes the last ten line of the file to the screen

Example         : tail stringmanip.sh

Output            :

[itstaff@localhost itstaff]$ tail stringmanip.sh

                3) stringcmp "$str"

                ;;

                4) stringconcat "$str"

                ;;

                5) stringrev "$str"

                ;;

                6) exit

                ;;

        esac

done

[itstaff@localhost itstaff]$

Optiin [n]        : Says the number of lines to be displayed

Example         : tail -5 stringmanip.sh

Syntax                        : mv [source filename] [destinatiin filename]

Description     : Moves the entire content from source file to destinatiin file

Example         : mv file.txt cpfile.txt

Output            :

[itstaff@localhost itstaff]$ cat file.txt

GE 2155 : Computer Practice Laboratory II

Department of Informatiin Technology

Unix Programming

[itstaff@localhost itstaff]$ cat cpfile.txt

cat: cpfile.txt: No such file or directory

[itstaff@localhost itstaff]$ mv file.txt cpfile.txt

[itstaff@localhost itstaff]$ cat file.txt

cat: file.txt: No such file or directory

[itstaff@localhost itstaff]$

3. Command      : pr

Syntax                        : pr [options] file

Description     : Used to print file contents

Example         : pr -1 os.txt

Output            :

4. Command      : cut

Syntax                        : cut [options] file

Description     : Cut the specified file

Example         : cut os.txt

Output            :

5. Command      : join

Syntax                        : join file1 file2

Description     : Used to join files

Example         : cut os.txt hmt.txt

Output            :

6. Command      : grep

Syntax                        : grep [pattern] [filename]

Description     : It searches the specified pattern or word in the given file

Example         : grep Unix file.txt

Output            :

[itstaff@localhost itstaff]$ cat file.txt

GE 2155 : Computer Practice Laboratory II

Department of Informatiin Technology

Unix Programming

[itstaff@localhost itstaff]$ grep Unix file.txt

Unix Programming

[itstaff@localhost itstaff]$

RESULT:

            Thus, the study of basic UNIX commands was done and its output was verified.