content: /*
   * The Alluxio Open Foundation licenses this work under the Apache License, version 2.0
   * (the "License"). You may not use this work except in compliance with the License, which is
   * available at www.apache.org/licenses/LICENSE-2.0
   *
   * This software is distributed on an "AS IS" basis, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
   * either express or implied, as more fully set forth in the License.
   *
   * See the NOTICE file distributed with this work for information regarding copyright ownership.
   */
  
  package alluxio.cli.extensions.command;
  
  import alluxio.cli.Command;
  import alluxio.cli.CommandUtils;
  import alluxio.conf.Configuration;
  import alluxio.conf.PropertyKey;
  import alluxio.exception.status.InvalidArgumentException;
  import alluxio.util.ExtensionUtils;
  
  import org.apache.commons.cli.CommandLine;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.io.File;
  import javax.annotation.concurrent.ThreadSafe;
  
  /**
   * Lists all installed extensions.
   */
  @ThreadSafe
  public final class LsCommand implements Command {
    private static final Logger LOG = LoggerFactory.getLogger(LsCommand.class);
  
    /**
     * Constructs a new instance of {@link LsCommand}.
     */
    public LsCommand() {
    }
  
    @Override
    public String getCommandName() {
      return "ls";
    }
  
    @Override
    public void validateArgs(CommandLine cl) throws InvalidArgumentException {
      CommandUtils.checkNumOfArgsEquals(this, cl, 0);
    }
  
    @Override
    public String getUsage() {
      return "ls";
    }
  
    @Override
    public String getDescription() {
      return "Lists JAR names for all installed extensions.";
    }
  
    @Override
    public int run(CommandLine cl) {
      for (File extension : ExtensionUtils
          .listExtensions(Configuration.getString(PropertyKey.EXTENSIONS_DIR))) {
        System.out.println(extension.getName());
      }
      return 0;
    }
  }
  