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.
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.