unix_shell project

This project implements a simple UNIX shell program that supports the execution of multiple commands chained by pipes (|) along with input/output redirection. The shell is capable of handling multiple pipes in a command, allowing users to create more complex command pipelines. It has been designed to mimic some functionalities of a traditional UNIX shell, providing a user-friendly way to interact with the system.

Getting Started

These instructions will get you a copy of the project up and running on your local machine for development and testing purposes.

Prerequisites

GCC Compiler (or any compatible C compiler)
Linux/Unix Environment (as it uses fork, pipe and exec which are specific to UNIX-like systems)

Installation

Clone the repository or download the source files.
Navigate to the project directory.
Compile the source files using a C compiler:

gcc -o shell shell.c

Run the executable:

./shell

Usage

Once you run the executable, you can enter commands in the following format:

command1 [arg1 arg2 ...] [| command2 [arg1 arg2 ...]] [< input_file] [> output_file] [>> append_output_file] [&]

Pipe symbol to chain multiple commands. The output of the preceding command will be the input to the following command. |
Redirect input from a file. <
Redirect output to a file (overwrite if file exists). >
Append output to a file. >>
Run command in the background (not wait for it to finish). >>&
For example:

cat file.txt | grep "keyword" > output.txt

Code Structure

The project consists of three primary functions:

parse - Parses a command string to extract individual commands and their arguments, as well as input/output redirection specifications.
execute - Forks a new process to execute the parsed command or chain of commands.
execute_pipeline - Manages the execution of multiple commands connected by pipes.

Functions Documentation

int parse(char* s, char* argv[MAX_PIPE_COMMANDS][MAX_CMD_LINE_ARGS])

s: A string containing the entire command input.
argv: A 2D array to store the commands and their arguments.
Return: The number of commands parsed.
int execute(char* input)
input: A string containing the entire command input.
Return: 0 on success, -1 on failure.
void execute_pipeline(char* args[MAX_PIPE_COMMANDS][MAX_CMD_LINE_ARGS], int n)
args: A 2D array containing the commands and their arguments.
n: The number of commands to execute.

EPW80/CPSC-351-unix-shell-C