Hands-On System Programming with Linux

The process and open files

To clearly understand the effect of fork on open files, we need to slightly digress and briefly understand some background information.

In fact, for those readers very new to performing I/O on files within the Unix paradigm, it will be beneficial to first read through the Appendix A, File I/O Essentials, before tackling this section.

A Unix/Linux process, upon startup, will by default be assigned three open files; we've discussed these basic points earlier in the book. For convenience, the three open files are called the stdin, stdout, and stderr of the process; they auto-default to the keyboard, the monitor, and, again, the monitor for stdin, stdout, and stderr respectively. Not only that, real applications will ...