Basic Unix Shell

This project implements a minimalist Unix-like shell in C, offering basic functionality for executing commands with support for I/O redirection, environment customization, built-in commands, and signal handling.

Features

• I/O Redirection: Supports <, >, >>, 2>, and &> for redirecting standard input, output, error streams, and appending to files. Redirection symbols should be surrounded by whitespace.
• Environment Customization: Uses a customizable prompt string, which defaults to a simple format but can be overridden by the PS1 environment variable.
• Built-in Commands: Includes basic navigation via cd and exiting the shell using exit.
• Shell Variable $?: Captures the exit status of the last executed command or the signal number (with bit 7 set) if terminated due to a signal.
• Signal Handling: Ignores ^C (SIGINT) at the shell level, allowing interruption of child processes without exiting the shell.

Limitations

While this shell implementation provides a basic set of features, it has several limitations:

• Limited Built-in Commands: Only supports a minimal set of built-in commands (cd and exit). Advanced shell functionalities like pushd, popd, dirs, and job control are not supported.
• No Scripting Support: Lacks support for shell scripting, including control flow statements (if, while, for), script execution, and function definitions.
• No Command History: Does not maintain a history of executed commands, thus cannot navigate through previous commands using the up and down arrow keys.
• No Tab Completion: Lacks tab completion for commands and file paths, a feature commonly found in more sophisticated shells.
• No Alias Support: Does not support command aliases, a feature that allows users to define shortcuts for long commands or command sequences.
• No Job Control: Lacks job control features, which allow users to suspend and resume processes, bring background processes to the foreground, and manage multiple processes more easily.

Prerequisites

Before building the shell, ensure you have GCC installed on your system as the compilation depends on it.

Building the Shell

The project includes a Makefile for easy compilation. Simply run the following command in the terminal within the project directory:

make

This will compile the source code into an executable named shell.