DSA Project Group 44 - Assignment Shell

The Project

The assignment shell is compiled using the following lines of code :

$> cd location_of_the_repo_on_your_machine\DSA-project-group-44\Project\dsa
$> cmake a
$> ./Shell

We scan the command in main.c and turn the string into a series of arguments or tokens using the parse(char *cmd, char **params, char *use_string) function.

The parse(char *cmd, char **params, char *use_string) function removes both unecessary whitespace both leading the string and within the string, removes escape sequence characters and stores each word of the command string into a list of tokens.

Each token in a string which is processed by the int execute(char **params, char*commands_str[], int (*commands_func[])(char **)) function.

The execute function forks a child process, identifies what set of instructions, be it custom or in-built, the token calls on and runs them in the child process.

The prompt shows the absolute path address of the directory the user is currently in (using the getcwd()) function as well as any folder the user might be “using” selected via the usefolder(char **args) function in <>.

The shell supports 8 custom made commands as well as almost all standard bash shell commands.

Error Handling in execute

If the Shell fails to fork a child process it returns fork: error_description

If the command doesn't exist in bash or isn't one of the 8 custom defined functions, the shell returns Command not found: name_of_invalid_command

If there is an error in executing the command the shell returns Shell: command_name error_description

switch

The usefolder(char **args) command functions like the standard bash command cd, with the added ability to access sibling folders without having to cd into their shared parent directory. It is called by switch. For example, for the given file structure.

folderC
    folderA
      folderD
    folderB

Suppose we are in folderA

$Group44Shell/folderC/folderA>switch folderB 
$Group44Shell/folderC/folderB>

$Group44Shell/folderC/folderA>switch folderD 
$Group44Shell/folderC/folderA/folderD>

$Group44Shell/folderC/folderA>switch .. 
$Group44Shell/folderC>

use

The usefolder(char **args) function saves the argument file’s name and indicates it in brackets at the end of the Group44Shell prompt. If any command is passed without its argument, it defaults to our saved file’s name. It is called by use.

For example, for the given file structure.

folderC
    folderA
      folderD
	  folderE
    folderB

Suppose we are in folderA

$Group44Shell/folderC/folderA>use folderD
$Group44Shell/folderC/folderA<FolderD>

$Group44Shell/folderC/folderA<folderD>switch folderB
$Group44Shell/folderC/folderB<FolderD>

$Group44Shell/folderC/folderA/folderE<FolderD>switch
$Group44Shell/folderC/folderA/folderD<FolderD>

test

The testfolder(char **args) function goes to the folder given as an argument to the setup command and runs the submitter.py present in the dist folder, if it exists. The output of the submitter.py, containing all the errors and outputs, is then stored in testLog.txt file in the main working directory.

For example, for the given file structure.

folderA
    dist
      submitter.py    

Now, if we type the following in the prompt:

test folderA

The program will run the submitter.py file and create a file testLog.txt with the output.

Hence, the new directory structure will be

folderA
   dist
     submitter.py 
testLog.txt   

setup

The setupfolder(char **args) function reads an indented file setup.txt from the Downloads folder present in the current working directory and then creates a folder structure in correspondence with it.

The argument to the setup command must match with the root directory mentioned at the top of the setup.txt.
Also the setup.txt file must be indented by using tab spaces.

For example, if the setup.txt file is:

assignment
  q1
  	solution
			main1
		testcases
		q12
			main2
	q2
		solution
	q3

Then, to create this structure, the command should be:

setup assignment

This will create a directory assignment in the working directory with all the sub-directories.

create

1. The create <assignment> command had 2 functions one to create the folder named assignment in the current directory using mkdir standard bash command and other function is to copy the contents of the dist folder and the problem statement from Downloads folder to the newly created assignment folder using cp standard bash command

$shell/Project/dsa> create assignment1
assignment1 is created and downloaded the required files

ERROR CASE

1. If assignment1 folder is already exist in current directory then

$shell/Project/dsa> create assignment1
mkdir: cannot create directory ‘/Project/dsa/assignment1’: File exists

update

1. The update <assignment> command had 2 functions one to delete the dist files in assignment folder using rm standard bash command and other function is copy the contents of Downloads folder using cp standard bash command which updates the contents of the dist folder and the problem statement in selected assignment

#Note: if any files that are needed to update from downloads other than dist files then make sure that the files have same old name

shell/Project/dsa>update assignment1
assignment2 is updated, old files are deleted & new files are downloaded

ERROR CASE

1. If assignment1 folder doesn’t exist in current directory

$shell/Project/dsa>update assignment1
rm: cannot remove '/Project/dsa/assignment2/dist': No such file or directory

submit

Submitfolder finds the file name in the current directory and create a zip file for it.

Folder C
	Folder A
		Folder D

$Group44Shell/folderC/folderA>submit folder D

It zips the file and pastes it in the Download directory.

$Group44Shell/Download-directory/folderD.zip

ERROR HANDLING

$Group44Shell/folderC/folderA>submit folder E

The output will be No such Folder

compare

Compare finds the file name in the current directory and compare it with the zip file in the Downloads directory.

FolderC
	FolderA
		FolderD

$Group44Shell/folderC/folderA>compare folderD folderD.zip

Files dir1.txt and Downloads/dir2.txt are identical

It will create dir1.txt and Downloads/dir2.txt and will contain the files in the folder and the zip file of the folder. diff will be used to print the files that are different in both folders.
ERROR HANDLING

$Group44Shell/folderC/folderA>compare folder E

The output will be NO SUCH FILE TO COMPARE