Custom Shell is a simple custom shell implementation in C. It supports executing external commands, built-in commands, input/output redirection, piping, and job control.

• cd <directory>: Change the current working directory.
• pwd: Print the current working directory.
• exit: Terminate the shell and all child processes.
• status: Display the exit status of the last executed command.
• history: Show the list of previously executed commands.
• jobs: List current background and suspended jobs with their PIDs and status.
• fg <PID>: Bring a background or suspended job to the foreground.
• bg <PID>: Resume a suspended job in the background.
• kill <PID> or kill -<SIGNAL> <PID>: Send a signal to a process.

• External Commands: Execute standard Linux commands (e.g., ls, ps, echo).
• Piping (|): Chain commands together (e.g., ls -l | grep .c).
• Redirection:
  • Input redirection: command < input_file
  • Output redirection (overwrite): command > output_file
  • Output redirection (append): command >> output_file
  • Error redirection: command 2> error_file
• Background Processes: Run commands in the background using & (e.g., sleep 10 &).
• Signal Handling:
  • Ctrl+C: Interrupt the foreground process.
  • Ctrl+Z: Suspend the foreground process.
• Environment Variables: Access environment variables using $VAR (e.g., echo $HOME).
• History Expansion:
  • !!: Re-execute the last command.
  • !n: Re-execute the command at index n in history.

• GCC Compiler
• Make

To compile the shell, run:

make

To clean build artifacts:

make clean

To rebuild from scratch:

make rebuild

Start the shell by running the executable:

./customshell

This shell has been fully checked for memory leaks using Valgrind

• Signal Handling: Uses sigaction to handle SIGINT, SIGTSTP, and SIGCHLD.
• Process Management: Uses fork(), execvp(), and waitpid() for process creation and control.
• Job Control: Maintains a linked list of Process Control Blocks (PCBs) to track background and suspended processes.
• Tokenization: Custom tokenizer to handle command-line arguments and quotes.