arkasarkar19 / linux_shell_implementation

Refer Readme.md

Linux_Shell_Imlementation

I have implemented a linux bash shell. The code is in C.

>>>This is my shell, use at our own risk <<<

COMMANDS HANDLED

• cd

  • cd command changes your present working directory to the directory or path entered as an argument.

  • Syntax : $ cd [directory_name / directory_path]

  • Example :
    

    • cd directory or cd dir1/dir2/dir3

       myterminal@arka:~/home/arkasarkar/Desktop/CAOS $ cd try
       myterminal@arka:~/home/arkasarkar/Desktop/CAOS/try $
       myterminal@arka:~/home/arkasarkar $ cd Desktop/CAOS/try
       myterminal@arka:~/home/arkasarkar/Desktop/CAOS/try $
      

    • cd .. , changes to the parent directory of the current directory.

       myterminal@arka:~/home/arkasarkar/Desktop/CAOS/try $ cd ..
       myterminal@arka:~/home/arkasarkar/Desktop/CAOS $
      

    • cd ~, changes to the home directory

       myterminal@arka:~/home/arkasarkar/Desktop/CAOS/try $ cd ~
       myterminal@arka:~/home/arkasarkar $
      

    • cd , works just like cd ~ command

       myterminal@arka:~/home/arkasarkar/Desktop/CAOS/try $ cd
       myterminal@arka:~/home/arkasarkar $
      

    • cd / , changes to the root directory

       myterminal@arka:~/home/arkasarkar/Desktop $ cd /
       myterminal@arka:~/ $
      

• echo

• echo command is used to display line of text/string that are passed as an argument.

• Syntax : echo [option] [text]

• Example:

  • echo “[text]”

         myterminal@arka:~/home/arkasarkar $ echo "hello"
         hello
         myterminal@arka:~/home/arkasarkar $Arka Sarkar
         2018222
    

  • echo -n [text] , -n omits a new trailing line after printing the text.

         myterminal@arka:~/home/arkasarkar $ echo -n "hello"
         hellomyterminal@arka:~/home/arkasarkar $
    

  • echo * , displays all the files/folders

         myterminal@arka:~/home/arkasarkar/Desktop/CAOS $ echo *
         a.out cat.c date.c demo1.c history.txt ls.c makefile mkdir.c rm.c try
    

• history

• Displays all the commands previously executed.

• Syntax : history [option]

• Example: * history

        myterminal@arka:~/home/arkasarkar/Desktop/CAOS $ history
        history
        mkdir try try2 try3
        mkdir t
        ls
        mkdir
        ry
        mkdir try
        ls
        ls
        ls -l
        ls -l -h -a
        cd demo
        ls
        cd
        ls
        ........ Cont..
  

  • history - c
    • clears the history.

• pwd

• Displays the present working directory

• Syntax : pwd

• Example : * pwd

          myterminal@arka:~/home/arkasarkar/Desktop/CAOS $ pwd
          current working directory :- /home/arkasarkar/Desktop/CAOS
  

• exit

• Exits the terminal

• Syntax : exit

• Example:

   myterminal@arka:~/home/arkasarkar/Desktop/CAOS $ exit
  

• ls

• Ls command displays all the files / folders in the present working directory

• Syntax : ls [option]

• Example:

  • ls

       myterminal@arka:~/home/arkasarkar/Desktop/CAOS $ ls
       a.out cat.c date.c demo1.c history.txt ls.c makefile mkdir.c rm.c try
    

  • ls -l , shows long format → all permisions, space , time modifed.

       myterminal@arka:~/home/arkasarkar/Desktop/CAOS $ ls -l
       total 60
       -rwxr-xr-x 1 arkasarkar arkasarkar 17584 Sep 1 22:05 a.out
       -rw-rw-r-- 1 arkasarkar arkasarkar 1281 Sep 1 13:39 cat.c
       -rw-rw-r-- 1 arkasarkar arkasarkar 1142 Aug 30 16:08 date.c
       -rw-rw-r-- 1 arkasarkar arkasarkar 4944 Sep 1 22:05 demo1.c
       -rw-rw-r-- 1 arkasarkar arkasarkar 1039 Sep 1 22:18 history.txt
       -rw-rw-r-- 1 arkasarkar arkasarkar 757 Aug 30 01:58 ls.c
       -rw-r--r-- 1 arkasarkar arkasarkar
       38 Aug 31 13:31 makefile
       -rw-rw-r-- 1 arkasarkar arkasarkar 1420 Aug 30 02:02 mkdir.c
       -rw-rw-r-- 1 arkasarkar arkasarkar 1144 Aug 30 16:03 rm.c
       drwxr-xr-x 2 arkasarkar arkasarkar 4096 Sep 1 21:12 try
    

  • ls -lh, formats into human readable form.

       total 60K
       -rwxr-xr-x 1 arkasarkar arkasarkar 18K Sep 1 22:05 a.out
       -rw-rw-r-- 1 arkasarkar arkasarkar 1.3K Sep 1 13:39 cat.c
       -rw-rw-r-- 1 arkasarkar arkasarkar 1.2K Aug 30 16:08 date.c
       -rw-rw-r-- 1 arkasarkar arkasarkar 4.9K Sep 1 22:05 demo1.c
       -rw-rw-r-- 1 arkasarkar arkasarkar 1.2K Sep 1 22:20 history.txt
       -rw-rw-r-- 1 arkasarkar arkasarkar 757 Aug 30 01:58 ls.c
       -rw-r--r-- 1 arkasarkar arkasarkar 38 Aug 31 13:31 makefile
       -rw-rw-r-- 1 arkasarkar arkasarkar 1.4K Aug 30 02:02 mkdir.c
       -rw-rw-r-- 1 arkasarkar arkasarkar 1.2K Aug 30 16:03 rm.c
       drwxr-xr-x 2 arkasarkar arkasarkar 4.0K Sep 1 21:12 try
    

• cat

• Read content from a file and displays it.

• Syntax : cat [filename]

• Example :

  • cat [filename]

    myterminal@arka:~/home/arkasarkar/Desktop/CAOS $ cat del.txt
    Hello
    myterminal@arka:~/home/arkasarkar/Desktop/CAOS $
    

• date

• Displays current date

• Syntax : date [arg]

• Example:

  • date

    myterminal@arka:~/home/arkasarkar/Desktop/CAOS $ date
    Sun Sep 1 22:31:43 IST 2019
    

  • date -R

    myterminal@arka:~/home/arkasarkar/Desktop/CAOS $ date -R
    Sun, 01 Sep 2019 22:31:54 +0530
    

• rm

• rm removes files or directories entered by the user.

• Syntax : rm [option] [filename]

• Example:

  • rm [filename]

    myterminal@arka:~/home/arkasarkar/Desktop/CAOS $ rm del.txt
    

  • rm -r [dir_name] , deletes a directory and its contents

    myterminal@arka:~/home/arkasarkar/Desktop/CAOS $ rm -r del
    

  • rm -f [filename] , forcefully deletes a file if write protected.

    myterminal@arka:~/home/arkasarkar/Desktop/CAOS $ rm -f del.txt
    

  • rm * , deletes all the files of the parent directory ( not the directories)

    myterminal@arka:~/home/arkasarkar/Desktop/CAOS $ rm *
    

  • rm -r * , empties the parent directory

    myterminal@arka:~/home/arkasarkar/Desktop/CAOS $ rm -r *
    

• mkdir

• mkdir creates an empty directory in the present working directory

• Syntax : mkdir [dir_name]

• Example :

  • mkdir [dir_name]

    myterminal@arka:~/home/arkasarkar/Desktop/CAOS $ mkdir hello
    myterminal@arka:~/home/arkasarkar/Desktop/CAOS $ ls
    a.out date.c hello
    ls.c
    mkdir.c try
    cat.c demo1.c history.txt makefile rm.c
    

  • mkdir [dir1_name] [dir2_name]

    myterminal@arka:~/home/arkasarkar/Desktop/CAOS $ mkdir hello hello2
    myterminal@arka:~/home/arkasarkar/Desktop/CAOS $ ls
    a.out date.c hello history.txt makefile rm.c
    cat.c demo1.c hello2 ls.c
    mkdir.c try
    

COMPILE AND RUNNING

demo1.c is the main file. Compile it on the terminal using gcc demo1.c -o main and run the executable main as ./main commands.