If you can enter commands into the shell, you can write shell scripts (also known as Bourne shell scripts). A shell script is a series of commands written in a file; the shell reads the commands from the file just as it would if you typed them into a terminal.

This chapter explores basic network applications—the clients and servers running in user space that reside at the application layer. Because this layer is at the top of the stack, close to end users, you may find this material more accessible than the material in Chapter 9. Indeed, you interact w...

Networking is the practice of connecting computers and sending data between them. That sounds simple enough, but to understand how it works, you need to ask two fundamental questions:

This chapter takes you deeper into the relationships between processes, the kernel, and system resources. There are three basic kinds of hardware resources: CPU, memory, and I/O. Processes vie for these resources, and the kernel’s job is to allocate resources fairly. The kernel itself is also a r...

When you first look in the /etc directory, you might feel a bit overwhelmed. Although most of the files that you see affect a system’s operations to some extent, a few are fundamental.

The point where the kernel starts its first user-space process, init, is significant—not just because that’s where the memory and CPU are finally ready for normal system operation, but because that’s where you can see how the rest of the system builds up as a whole. Prior to this point, the kerne...

You now know the physical and logical structure of a Linux system, what the kernel is, and how to work with processes. This chapter will teach you how the kernel starts— or boots. In other words, you’ll learn how the kernel moves into memory up to the point where the first user process starts.

In Chapter 3, we discussed some of the top-level disk devices that the kernel makes available. In this chapter, we’ll discuss in detail how to work with disks on a Linux system. You’ll learn how to partition disks, create and maintain the filesystems that go inside disk partitions, and work with ...

This chapter is a basic tour of the kernel-provided device infrastructure in a functioning Linux system.

This chapter is a guide to the Unix commands and utilities that will be referenced throughout this book. This is preliminary material, and you may already know a substantial amount of it. Even if you think you’re up to speed, take a few seconds to flip through the chapter just to make sure, espec...

Go引言非常入门的一本书？准确来说是一篇GO的入门文章，用于学学英语和简单了解GO还不错，并且词汇和语法都比较简洁易懂。话不多说，下面就来看看这篇文章的翻译。原文[链接]1.介绍GO它是由谷歌工程师创建的，设计这门语言的主要目标是：提高项目的编译和运行速度入门门槛足够低，但是也要避免过于简单和低级。具备可移...

At first glance, a modern operating system such as Linux is very complicated, with a dizzying number of pieces simultaneously running and communicating. For example, a web server can talk to a database server, which could in turn use a shared library that many other programs use. But how does it ...

Chapter 19 discussed the Manager application. It showed that the ManagerServlet class implemented the ContainerServlet interface to get access to Catalina internal objects. This chapter now shows that managing Tomcat can be achieved more sophisticatedly using the Java Management Extensions (the J...

注意：由于Tomcat 4中的Manager应用程序比Tomcat 5中的稍微简单一些，它是一个更好的学习工具，因此在本章中进行了讨论。阅读本章后，您应该也能理解Tomcat 5中的Manager应用程序的工作原理。

For a web application to be available, the context representing it must first be deployed to a host. In Tomcat, a context can be deployed as a WAR file or by copying the whole application to the webapps directory under the Tomcat installation directory. For each application you deploy, you can op...

This chapter focuses on Tomcat startup using two classes in the org.apache.catalina.startup package, Catalina and Bootstrap. The Catalina class is used to start and stop a Server object as well as parse the Tomcat configuration file, server.xml. The Bootstrap class is the entry point that creates...

In many circumstances, you need a chance to do clean-up when the user shuts down your application. The problem is, the user does not always follow the recommended procedure to exit. For example, in a Tomcat deployment you start the servlet container by instantiating a Server object and call its s...

As you have seen in the previous chapters, we use a Bootstrap class to instantiate a connector, a context, wrappers, and other components. Once you have those objects, you then associate them with each other by calling the set methods of various objects. For example, to instantiate a connector an...

In previous chapters you have seen how you can have a servlet container by instantiating a connector and a container and then associating them with each other. Only one connector could be used, and that was to serve HTTP requests on port 8080. You could not add another connector to service HTTPS ...

Two topics of discussion in this chapter are hosts and engines. You use a host if you want to run more than one context in the same Tomcat deployment. In theory, you do not need a host if you only have one context, as stated in the description of the org.apache.catalina.Context interface:

As you have witnessed in the previous chapters, a context represents a web application and contains one or more wrappers, each of which represents a servlet definition. However, a context requires other components as well, notably a loader and a manager. This chapter explains the org.apache.catal...

You have learned in Chapter 5 that there are four types of containers: engine, host, context, and wrapper. You have also built your own simple contexts and wrappers in previous chapters. A context normally has one or more wrappers, in which each wrapper represents a servlet definition. This chapt...

Some contents of a web application are restricted, and only authorized users are allowed to view them, after they supplied the correct user name and password. The servlet technology supports applying security constraint to those contents via the configuration of the deployment descriptor (web.xml...

Catalina supports session management through a component called manager, which is represented by the org.apache.catalina.Manager interface. A manager is always associated with a context. Among others, a manager is responsible for creating, updating, and destroying (invalidating) session objects a...

You have seen a simple loader implementation in the previous chapters, which was used for loading servlet classes. This chapter explains the standard web application loader, or loader for short, in Catalina. A servlet container needs a customized loader and cannot simply use the system's class lo...

A logger is a component for recording messages. In Catalina a logger is associated with a container and is relatively simpler than other components. Tomcat provides various loggers in the org.apache.catalina.logger package. The application that accompanies this chapter can be found in the ex07.py...

Catalina consists of many components. When Catalina is started, these components need to be started as well. When Catalina is stopped, these components must also be given a chance to do a clean-up. For example, when the container is stopped, it must invoke the destroy method of all loaded servlet...

A container is a module that processes the requests for a servlet and populates the response objects for web clients. A container is represented by the org.apache.catalina.Container interface and there are four types of containers: Engine, Host, Context, and Wrapper. This chapter covers Context a...

The connector in Chapter 3 worked fine and could have been perfected to achieve much more. However, it was designed as an educational tool, an introduction to Tomcat 4's default connector. Understanding the connector in Chapter 3 is key to understanding the default connector that comes with Tomca...

As mentioned in Introduction, there are two main modules in Catalina: the connector and the container. In this chapter you will enhance the applications in Chapter 2 by writing a connector that creates better request and response objects. A connector compliant with Servlet 2.3 and 2.4 specificati...