Interactive-C-Shell

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Description

This project is an interactive shell written in C/C++ that mimics the functionality of a basic POSIX shell. The shell allows users to execute commands, manage processes, and handle input/output redirections and pipelines. It supports both background and foreground processes, as well as several built-in shell commands.

Features

Shell Built-ins:

• cd: Change the current working directory.
• pwd: Print the current working directory.
• echo: Display messages, without handling escape sequences.
• ls: List directory contents with support for -a and -l flags.

System Commands:

• Execute any system command like vi, gedit, etc., in the foreground or background using &.

Additional Features:

• pinfo: Display process information for the shell or a given PID.
• search: Search for a file or folder in the current directory recursively.
• I/O Redirection: Handle input (<), output (>), and append (>>) redirection.
• Pipelines: Support command chaining using pipes (|).
• Signal Handling: Manage foreground/background processes with CTRL-Z, CTRL-C, and CTRL-D.
• Auto-complete: Pressing TAB will auto-complete files or directories in the current path.
• History (BONUS): Track and display the last 10 commands entered by the user.

Usage

Running the Shell:

To compile and run the shell, follow these steps:

make
./a.out

Example Shell Prompt:

<username>@<system_name>:<current_directory>$

Built-in Command Usage:

• cd <directory>: Change directory.
• pwd: Print the working directory.
• echo <message>: Display a message.
• ls [flags] [directory]: List files with support for -a, -l, and directory listing.

System Command Usage:

• gedit &: Run gedit in the background.
• pinfo: Display process information.

I/O Redirection:

• echo "Hello" > output.txt: Redirect output to a file.
• cat < input.txt: Read input from a file.

Pipelines:

• cat file.txt | wc: Pipe the output of cat to wc.

Error Handling

• The shell includes error handling for invalid commands, file/directory paths, and invalid arguments for built-in commands.
• Appropriate error messages are displayed when commands cannot be executed.

Limitations

• No support for escape sequences in echo.
• No handling of complex redirection such as 2>&1.
• Internal commands like cd, ls, pwd, etc., do not run in the background.

Directory Structure

<roll_number>_Assignment2/
├── README.md
├── makefile
├── shell.c
└── other_sources/

How to Compile

To compile the code, use the make command, which will generate the a.out file:

make

Assumptions

• The shell assumes valid input for the built-in commands.
• Environmental variables and complex shell features like quotes and escape sequences are not handled.

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