UnixCommands.java revision 9532:15b7d6a7c643 
1/*
2 * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 */
23
24import java.io.File;
25import java.util.HashMap;
26import java.util.Map;
27
28/**
29 * Utility class for finding the command on the current system
30 */
31public class UnixCommands {
32
33    public static final boolean isUnix = ! System.getProperty("os.name").startsWith("Windows");
34    public static final boolean isLinux = System.getProperty("os.name").startsWith("Linux");
35    public static final boolean isSunOS = System.getProperty("os.name").equals("SunOS");
36
37    private static final String[] paths = {"/bin", "/usr/bin"};
38
39    private static Map<String,String> nameToCommand = new HashMap<>(16);
40
41    /**
42     * Throws Error unless every listed command is available on the system
43     */
44    public static void ensureCommandsAvailable(String... commands) {
45        for (String command : commands) {
46            if (findCommand(command) == null) {
47                throw new Error("Command '" + command + "' not found; bailing out");
48            }
49        }
50    }
51
52    /**
53     * If the path to the command could be found, returns the command with the full path.
54     * Otherwise, returns null.
55     */
56    public static String cat()   { return findCommand("cat"); }
57    public static String sh()    { return findCommand("sh"); }
58    public static String kill()  { return findCommand("kill"); }
59    public static String sleep() { return findCommand("sleep"); }
60    public static String tee()   { return findCommand("tee"); }
61    public static String echo()  { return findCommand("echo"); }
62
63    public static String findCommand(String name) {
64        if (nameToCommand.containsKey(name)) {
65            return nameToCommand.get(name);
66        }
67        String command = findCommand0(name);
68        nameToCommand.put(name, command);
69        return command;
70    }
71
72    private static String findCommand0(String name) {
73        for (String path : paths) {
74            File file = new File(path, name);
75            if (file.canExecute()) {
76                return file.getPath();
77            }
78        }
79        return null;
80    }
81}
82