🐚 [myshell] A Simple Shell with Multiprocessing and Pipes

About

myshell is a simple shell (command-line interpreter) capable of handling one command (with or without pipes).

It reads a single line from the stdin, lexes it, then executes it via execvp.

_{More information can be found here.}

Team members and contribution

• Gary Tou (@garyhtou)
  • Parsing and lexing function (Helper::lex) that also handles quoted strings
  • File descriptors and forking
  • Object orientated Command class for more organized code
• Castel Villalobos (@impropernoun)
  • Makefile
  • Handle difference between single vs multi-command
  • Set up pipes
• Hank Rudolph (@hankrud)
  • Setup and call execvp
  • Convert C++ string to c string
  • Prompt and get input

Strengths and Weaknesses

Strength:

• Handles quoted strings. eg. echo "it works on my machine"
• Object orientated design (See Command class)
• Able to handle "unlimited" commands and arguments (not restricted to the 10 commands and 20 arguments per command requirement from the instruction)
• Well commented

Weaknesses:

• Shell does not run continuously
• Does not handle changing operators such as &&, ||, and ; (it does handle |)
• Does not handle environment variables

The program is composed of three files:

• myshell.cpp: Contains the main function and handles the coordination of multiple commands and pipes.
  • Gets the inputted command and parses and lexes it.
  • Then runs it as either a single command (no pipes) or multi-command (with pipes).
• command.cpp: Responsible for executing the commands and managing pipe file descriptors.
• helper.cpp: Contains functions that parses and lexes commands into tokens, as well as handles whitespace.