| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.karaf.shell.commands; |
| |
| import java.io.BufferedReader; |
| import java.io.File; |
| import java.io.FileReader; |
| import java.io.IOException; |
| import java.io.InputStreamReader; |
| import java.net.MalformedURLException; |
| import java.net.URL; |
| import java.util.List; |
| |
| import org.apache.felix.gogo.commands.Argument; |
| import org.apache.felix.gogo.commands.Command; |
| import org.apache.felix.gogo.commands.Option; |
| import org.apache.karaf.shell.console.AbstractAction; |
| |
| @Command(scope = "shell", name = "head", description = "Displays the first lines of a file.") |
| public class HeadAction extends AbstractAction { |
| |
| private static final int DEFAULT_NUMBER_OF_LINES = 10; |
| |
| @Option(name = "-n", aliases = {}, description = "The number of lines to display, starting at 1.", required = false, multiValued = false) |
| private int numberOfLines; |
| |
| @Argument(index = 0, name = "paths or urls", description = "A list of file paths or urls to display separated by whitespaces.", required = false, multiValued = true) |
| private List<String> paths; |
| |
| protected Object doExecute() throws Exception { |
| //If no paths provided assume standar input |
| if (paths == null || paths.size() == 0) { |
| if (log.isDebugEnabled()) { |
| log.debug("Heading STDIN"); |
| } |
| |
| head(new BufferedReader(new InputStreamReader(System.in))); |
| } else { |
| for (String filename : paths) { |
| BufferedReader reader; |
| |
| // First try a URL |
| try { |
| URL url = new URL(filename); |
| if (log.isDebugEnabled()) { |
| log.debug("Heading URL: " + url); |
| } |
| reader = new BufferedReader(new InputStreamReader(url.openStream())); |
| } |
| catch (MalformedURLException ignore) { |
| // They try a file |
| File file = new File(filename); |
| if (log.isDebugEnabled()) { |
| log.debug("Heading file: " + file); |
| } |
| reader = new BufferedReader(new FileReader(file)); |
| } |
| |
| try { |
| head(reader); |
| } |
| finally { |
| try { |
| reader.close(); |
| } catch (IOException e) { |
| // Ignore |
| } |
| } |
| } |
| } |
| return null; |
| } |
| |
| private void head(final BufferedReader reader) throws IOException { |
| String line; |
| int lineno = 1; |
| |
| if (numberOfLines < 1) { |
| numberOfLines = DEFAULT_NUMBER_OF_LINES; |
| } |
| |
| while ((line = reader.readLine()) != null && lineno <= numberOfLines) { |
| System.out.println(line); |
| lineno++; |
| } |
| } |
| } |