lttng-tools-java/src/main/java/org/lttng/tools/utils/ShellUtils.java

   1 /*
   2  * Copyright (C) 2015, EfficiOS Inc., Alexandre Montplaisir <alexmonthy@efficios.com>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along
  15  * with this program; if not, write to the Free Software Foundation, Inc.,
  16  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  17  */
  18
  19 package org.lttng.tools.utils;
  20
  21 import java.io.IOException;
  22 import java.lang.ProcessBuilder.Redirect;
  23 import java.nio.file.Files;
  24 import java.nio.file.Path;
  25 import java.util.Arrays;
  26 import java.util.List;
  27 import java.util.StringJoiner;
  28
  29 /**
  30  * Utility methods to execute commands on the command line.
  31  *
  32  * @author Alexandre Montplaisir
  33  */
  34 public final class ShellUtils {
  35
  36     private ShellUtils() {}
  37
  38     /**
  39      * Simple command to test that the environment / stdout are working
  40      * correctly.
  41      *
  42      * @param args
  43      *            Command-line arguments
  44      */
  45     public static void main(String[] args) {
  46         List<String> command = Arrays.asList("ls", "-l");
  47         executeCommand(command);
  48     }
  49
  50     /**
  51      * Execute a shell command and retrieve its return value.
  52      *
  53      * @param command
  54      *            The command to execute, as a list of individual arguments (do
  55      *            not use spaces)
  56      * @return If the command returned successfully (ret code = 0)
  57      */
  58     public static boolean executeCommand(List<String> command) {
  59         try {
  60             /* "echo" the command to stdout */
  61             StringJoiner sj = new StringJoiner(" ", "$ ", "");
  62             command.stream().forEach(sj::add);
  63             System.out.println(sj.toString());
  64
  65             ProcessBuilder builder = new ProcessBuilder(command);
  66             builder.redirectErrorStream(true);
  67             builder.redirectOutput(Redirect.INHERIT);
  68
  69             Process p = builder.start();
  70             int ret = p.waitFor();
  71
  72             System.out.println(String.format("(returned from command: %d)", ret));
  73
  74             return (ret == 0);
  75
  76         } catch (IOException | InterruptedException e) {
  77             return false;
  78         }
  79     }
  80
  81     /**
  82      * Execute a shell command and retrieve its output.
  83      *
  84      * @param print
  85      *            Should the output also be printed to stdout as usual
  86      * @param command
  87      *            The command to execute, as a list of individual arguments (do
  88      *            not use spaces)
  89      * @return The output of the command, as one list element per line
  90      */
  91     public static List<String> getOutputFromCommand(boolean print, List<String> command) {
  92         try {
  93             /* "echo" the command to stdout */
  94             StringJoiner sj = new StringJoiner(" ", "$ ", "");
  95             command.stream().forEach(sj::add);
  96             System.out.println(sj.toString());
  97
  98             Path tempFile = Files.createTempFile("test-output", null);
  99
 100             ProcessBuilder builder = new ProcessBuilder(command);
 101             builder.redirectErrorStream(true);
 102             builder.redirectOutput(Redirect.to(tempFile.toFile()));
 103
 104             Process p = builder.start();
 105             p.waitFor();
 106
 107             List<String> lines = Files.readAllLines(tempFile);
 108             Files.delete(tempFile);
 109
 110             if (print) {
 111                 /* Also print the output to the console */
 112                 lines.stream().forEach(System.out::println);
 113             } else {
 114                 System.out.println("(output silenced)");
 115             }
 116
 117             System.out.println("(returned from command)");
 118             return lines;
 119
 120         } catch (IOException | InterruptedException e) {
 121             return null;
 122         }
 123     }
 124 }