#!/usr/bin/c++script
// Demonstration of the COMMAND object
progdesc ("Demonstration of the COMMAND object");

// Using the ls command
	cout << "================ ls\n";
	for (auto &&f:COMMAND("ls").run()){
		cout << format ("{}\n",f.line);
	}
// Using the ls -l
	cout << "================ ls -l\n";
	for (auto &&f:COMMAND("ls -l").run()){
		cout << format ("{}\n",f.line);
	}
// Using an unknown command
// We see that normal output and error messages are merge in a single range
// The function is_error() and is_output() are used to tell them apart
	cout << "================ unknown\n";
	for (auto &&f:COMMAND("unknown").run()){
		if (f.is_error()){
			cout << format ("error message: {}\n",f.line);
		}else if (f.is_output()){
			cout << format ("normal output: {}\n",f.line);
		}
	}
// The command may be any bash expression.
	cout << "================ ls -l | tail -2\n";
	for (auto &&f:COMMAND("ls -l | tail -2").run()){
		cout << format ("{}\n",f.line);
	}
// Here we use tests/printlines to produce normal output and error messages.
// We use COMMAND::store_errors() which copies to the vector called errors
// and filter out all error messages. So in the loop, we only get normal output.
	COMMAND c4 ("tests/printlines -n5 -e3");
	cout << format("================ {}\n",c4.get());
	vector<string> errors;
	for (auto &&f:c4.run()
		| COMMAND::store_error(errors)){
		cout << format ("{}\n",f.line);
	}
	for (auto &e:errors) cout << format ("errors {}\n",e);