Custom Bash Shell

This project was part of my CS252 Systems Programming course at Purdue.

Built a robust shell environment replicating GNU Bash functionality with advanced features:

Command Processing

• Developed sophisticated command parser handling:
  • Complex command pipelines with multiple stages
  • I/O redirection (>, », <, 2>, &>) with file descriptor management
  • Command substitution ($(command)) and variable expansion
  • Environment variable management and PATH resolution
  • Wildcard expansion and filename globbing

Process Management

• Implemented job control system tracking foreground/background processes
• Built process group management for pipeline execution
• Added signal handlers for:
  • Ctrl-C (SIGINT) with proper process group termination
  • Ctrl-Z (SIGTSTP) for job suspension
  • SIGCHLD for zombie process cleanup and job status updates
• Managed process states (Running, Stopped, Terminated) with job table

Interactive Features

• Developed line editing with:
  • Emacs-style key bindings (Ctrl-A, Ctrl-E, etc.)
  • History navigation with search (Ctrl-R)
  • Context-aware tab completion for commands, files, and directories
• Implemented command history with persistent storage
• Added shell scripting support:

  • Conditional execution (&&,

    )

  • Subshell execution with proper environment inheritance
  • Exit status checking and error handling