C-Shell

A custom shell implementation in C, supporting various built-in commands, process management, and I/O redirection.

Features

Built-in Commands

• hop: Changes the current working directory.

  • Usage: hop <path>
  • Supports flags: . (current), .. (parent), ~ (home), - (previous).

• reveal: Lists files and directories.

  • Usage: reveal <flags> <path>
  • Flags: -a (show hidden), -l (long format).
  • Color-coded output for files, directories, and executables.

• log: Manages command history.

  • Usage: log (show history), log purge (clear history), log execute <index> (run command from history).
  • Stores up to 15 commands. Prevents duplicates.

• activities: Lists all currently running processes spawned by the shell.

  • Shows PID, Command Name, and State (Running/Stopped).

• ping: Sends a signal to a specific process.

  • Usage: ping <pid> <signal_number>

• fg: Brings a background process to the foreground.

  • Usage: fg <pid>

• bg: Changes a stopped background process to running (in the background).

  • Usage: bg <pid>

System Capabilities

• Command Execution: Executes standard system commands (e.g., ls, cat, sleep) using execvp.
• Background Processes: Supports running commands in the background using &.
• I/O Redirection:
  • >: Output redirection (overwrite).
  • >>: Output redirection (append).
  • <: Input redirection.
• Piping: Supports piping between commands using |.
• Signal Handling:
  • Ctrl+C (SIGINT): Interrupts the foreground process.
  • Ctrl+Z (SIGTSTP): Pushes the foreground process to the background (stopped).
  • Ctrl+D: Logs out of the shell.

Compilation and Usage

1. Navigate to the shell directory:

   cd shell

2. Compile the shell:

   make

3. Run the shell:

   ./shell.out

File Structure

• src/: Source code files (.c).
• include/: Header files (.h).
• Makefile: Build configuration.

Implementation Details

• Parser: Tokenizes input handling spaces, tabs, and special characters.
• Process Management: Tracks background processes and updates their status.
• History: Persists command history across sessions (stored in a log file).