File management is a most evident module of operating system. Information can be stored in computer on several different types of physical media such as magnetic disk, optical disk and magnetic tapes. Each and every media has its own physical organizations and characteristics. Every media is controlled by a device such as tape derive or disk device according to its own particular characteristics. These properties comprise with capacity, speed, access methods (Sequential or random access method) and data transfer rate. the operating system provides a uniform logical view of information storage for convenient use of computer system. The operating system extracts from the physical properties of its storage devices to define a logical storage unit.
Operating system plots files onto physical media and access these files through the storage devices. A file is basically a collection of relevant information defined by its creator. generally, files represent the data and program (both object and source form). Data files can be alphabetic, numeric and alphanumeric. Files may be formatted rigidly or may be free-form such as text files. A file basically consists of a sequence of bits, bytes, lines or records and meanings are defined by their creator. A file is an extremely general concept. The implementation of abstract concept of file with the help of operating system is done by using mass storage media such as disks, tapes and devices which control them. The files are usually organized into directories to make their use easy.
Ultimately when multiple users have access to files it can be appropriate to control by whom and in what way files may be accessed. The operating system is accountable for following activities in association with file management
- Creation and deletion of files.
- Creation and deletion of directories.
- Plotting of files onto secondary storage.
- Provision of primitives for manipulating directories and files.
There are several different system calls which deals with files. First of all, there is need to create and delete files. Moreover, system call requires the name of files and may be some attributes of file. Once the file created it can be open for use and can be write, read or reposition. Ultimately file need to be closed if it is no longer require to use.