code: protected final void printCommandLine(@Nonnull String[] cmd, @CheckForNull FilePath workDir) {
          StringBuilder buf = new StringBuilder();
          if (workDir != null) {
              buf.append('[');
              if(showFullPath)
                  buf.append(workDir.getRemote());
              else
                  buf.append(workDir.getRemote().replaceFirst("^.+[/\\\\]", ""));
              buf.append("] ");
          }
          buf.append('$');
          for (String c : cmd) {
              buf.append(' ');
              if(c.indexOf(' ')>=0) {
                  if(c.indexOf('"')>=0)
                      buf.append('\'').append(c).append('\'');
                  else
                      buf.append('"').append(c).append('"');
              } else
                  buf.append(c);
          }
          listener.getLogger().println(buf.toString());
          listener.getLogger().flush();
      }
docs: Prints out the command line to the listener so that users know what we are doing.