README.md

Parser for osh for CSCE 451/851

This is a fork of the parser from the former GTA Yutaka Tsutano. It has a few bug fixes and is more tailored for the current version of the programming assignment.

1 Usage

Read main.cpp for usage and command.hpp for understanding the data structure.

1.1 Compiling & Running on CSE

A Makefile is provided to make compilation easy. For your programming assignment, this is where you would add any new commands for testing, or copying over the CSE servers, etc.

1.2 Parsing

parse_command_string() returns a vector of parsed commands (defined in command.hpp) from a line of text input from the terminal. As an example:

// 1. Get a line from the terminal.
std::string input_line;
std::getline(std::cin, input_line);
// input into terminal "echo hello world | sort | uniq > test.txt";

// 2. Parse.
std::vector<shell_command> shell_commands = parse_command_string(input_line);

This is all you need to do to parse the input string. Now you can step through the commands in the shell_commands vector to implement the rest of the assignment.

1.3 Printing the Parsed Commands

It is helpful to print the parsed commands when implementing the execution part of the shell. You can do so with the following code:

std::cout << "-------------------------\n";
for (const auto& cmd : shell_commands) {
    std::cout << cmd;
    std::cout << "-------------------------\n";
}

For example, the result of parsing echo hello world | sort | uniq > test.txt above would be:

-------------------------
cmd: echo
arg: hello
arg: world
cin_file:
cin_mode: term
cout_file:
cout_mode: pipe
next_mode: always
-------------------------
cmd: sort
cin_file:
cin_mode: pipe
cout_file:
cout_mode: pipe
next_mode: always
-------------------------
cmd: uniq
cin_file:
cin_mode: pipe
cout_file: test.txt
cout_mode: file
next_mode: always
-------------------------