Linux Network Programming, Part 1 By Ivan Griffin and John Nelson

This is the first of a series of articles about how to devlop networked applications using the various interfaces available on Linux.

Like most other Unix-based operating systems, Linux supports TCP/IP as its native network transport. In this series, we will assume you are fairly familiar with C programming on Linux and with Linux topics such as signals, forking, etc.

This article is a basic introduction to using the BSD socket interface for creating networked applications. In the next article, we will deal with issues involved in creating (network) daemon processes. Future articles will cover using remote procedure calls and developing with CORBA/distributed objects.

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Introduction To Unix Signals Programming

What Are Signals?
Signals, to be short, are various notifications sent to a process in order to notify it of various "important" events. By their nature, they interrupt whatever the process is doing at this minute, and force it to handle them immediately. Each signal has an integer number that represents it (1, 2 and so on), as well as a symbolic name that is usually defined in the file /usr/include/signal.h or one of the files included by it directly or indirectly (HUP, INT and so on. Use the command 'kill -l' to see a list of signals supported by your system).

Each signal may have a signal handler, which is a function that gets called when the process receives that signal. The function is called in "asynchronous mode", meaning that no where in your program you have code that calls this function directly. Instead, when the signal is sent to the process, the operating system stops the execution of the process, and "forces" it to call the signal handler function. When that signal handler function returns, the process continues execution from wherever it happened to be before the signal was received, as if this interruption never occurred......

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Manipulating Files And Directories In Unix

By guy keren

The following tutorial describes various common methods for reading and writing files and directories on a Unix system. Part of the information is common C knowledge, and is repeated here for completeness. Other information is Unix-specific, although DOS programmers will find some of it similar to what they saw in various DOS compilers. If you are a proficient C programmer, and know everything about the standard I/O functions, its buffering operations, and know functions such as fseek() or fread(), you may skip the standard C library I/O functions section. If in doubt, at least skim through this section, to catch up on things you might not be familiar with, and at least look at the standard C library examples.

General Unix File System Structure
In the Unix system, all files and directories reside under a single top directory, called root directory, and denoted as "/". Even if the computer has several hard disks attached, they are all combined in a single directories tree. It is up to the system administrator to place all disks on this tree. Each disk is being connected to some directory in the file system. This connection operation is called "mount", and is usually done automatically when the system starts running.

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