/*
 *  gnu/tools/Printenv.java -- display system properties
 *  Copyright (C) 1998 Wes Biggs
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

package gnu.tools;
import java.util.Enumeration;

/**
 * Printenv is a clone of /usr/bin/printenv, except using the
 * Java virtual machine's system properties.
 *
 * Usage: java gnu.tools.Printenv [--help] [--version] [property]...
 *
 * @author <A HREF="mailto:wes@cacas.org>Wes Biggs</A>
 * @version 1.00, 19 November 1998
 */
public class Printenv {
  private Printenv() { }
  private static String translate(String val) {
    StringBuffer sb = new StringBuffer();
    char c;
    for (int i = 0; i < val.length(); i++) {
      switch (c = val.charAt(i)) {
      case '\n':
	sb.append("\\n");
	break;
      case '\r':
	sb.append("\\r");
	break;
      case '\t':
	sb.append("\\t");
	break;
      case '\\':
	sb.append("\\\\");
	break;
      default:
	sb.append(c);
      }
    }
    return sb.toString();
  }

  /** Invoke Printenv with the command line arguments. */
  public static void main(String[] argv) {
    String[] lookFor = null;
    int i = 0;
    if (argv.length > 0) {
      if (argv[0].equals("--help")) {
	System.out.println("Usage: java gnu.tools.Printenv [--help] [--version] [property ...]");
	System.out.println("If no property is specified, print them all.");
	System.out.println("");
	System.out.println("  --help      display this help and exit");
	System.out.println("  --version   output version information and exit");
	System.exit(0);
      } else if (argv[0].equals("--version")) {
	System.out.println("gnu.tools.Printenv 1.00, 19 November 1998");
	System.exit(0);
      }
    }
      
    Enumeration ee = System.getProperties().keys();
    String s;
    boolean b;
    while (ee.hasMoreElements()) {
      s = (String) ee.nextElement();
      b = (argv.length == 0);
      for (i = 0; i < argv.length; i++) {
	if (argv[i].equals(s))
	  b = true;
      }
      if (b) System.out.println(s + "=" + translate(System.getProperty(s)));
    }
  }
}