hwsh

Created for BLG312E Computer Operating Systems Spring 2024 course, as the first homework

This assignment involves implementing a command-line shell that can be run in batch mode. The shell is initiated by specifying a batch file on its command line, which contains a list of commands to be executed. Each line in the batch file can contain multiple commands separated by ; or |. Commands separated by ; should be run simultaneously or concurrently, while commands separated by | should be executed with the output of the preceding commands piped as input to the subsequent commands.

Features

• Execute multiple commands separated by ; simultaneously
• Pipe the outputs of each command before | to each command after | (check REQUIREMENTS.md)
• Support for cd command to change the working directory
• Support for history command to display previous commands
• Exit the shell using the quit command

Implementation Details

• Tokenize the command based on | and ;
• Use fork() to create new processes
• Use execvp() to execute commands
• Use waitpid() system call to wait for concurrent commands to finish
• Use temporary files to handle many-to-many "piping"
• Properly handle command arguments and termination with NULL

Compilation

To compile the project, navigate to the project directory and run the following command in your terminal:

make

This will create an executable file named hwsh.

Usage

To run the shell with a script, use the following command:

./hwsh <batchfile>

Replace <batchfile> with the name of your batch file. For example, if your batch file is named script.sh, you would run:

./hwsh script.sh