<?php
	class Shell {
		/* Define constants */
		// This can be set to null for unrestricted buffer space
		const MAX_OUTPUT_BUFFER = 256;
		
		/* Define static properties */
		private static $output_buffer = array();
		
		/**
		 * Execute a command, add the output to the buffer stack
		 * @return Int Command return status
		 * @param $command String
		 */
		static function exec($command) {
			@exec($command, $tmp_ob, $status);
			Shell::$output_buffer = array_merge((array) Shell::$output_buffer, (array) $tmp_ob);
			while(count(Shell::$output_buffer) > Shell::MAX_OUTPUT_BUFFER && Shell::MAX_OUTPUT_BUFFER != null) {
				array_shift(Shell::$output_buffer);
			}
			return (int) $status;
		}
		
		/**
		 * Flush the buffer stack
		 * @return null
		 */
		static function flush() {
			Shell::$output_buffer = array();
		}
		
		/**
		 * Print the buffer stack
		 * @return null
		 */
		static function output() {
			foreach(Shell::$output_buffer as $output_line) {
				printf("%s\n", $output_line);
			}
		}
	}
?>