Run the command make all to create the shell.

The shell is present in the executable file "shell"

Display :

<user_name @ sys_name : cwd>
~ is the place where the executable shell is present.

ls:

ls <directory name> -a -l
the flags and the directory name can be given in any order.
Even ~ related paths can be given.

cd:

cd <directory name>
if the directory exits then it changes the directory to the one provided.

echo:

echo <anything>
prints out the string given removing the extra spaces in between.

pwd:

pwd
prints the pwd of the shell.

pinfo:

pinfo <pid>
if no pid is provided , the pinfo of the shell is printed.
for a given pid , the required info is printed.

processess:

bg - if the processess are given without & at the end , the process is run and shell waits till it's completion.
fg - it prints the pid of the process that is just made.
     after the process ends, it gives info about the process that ended and the exit status.

';' seperated command:

many commands can be given seperated by a ';' and there are run sequentially.

history:

history <Number>
gives the latest (<=)10 commands entered in the shell.
given Number(<=10) , it prints that many number of latest commands from history.