FILE SYSTEM STORAGE
1 File Concept
ü A file is
a named collection of related information that is recorded on secondary storage.
ü From a user’s
perspective, a file is the smallest allotment of logical secondary storage;
that is, data cannot be written to secondary storage unless they are within a
file is a sequence of characters organized into lines (and possibly pages).
file is a sequence of subroutines and functions, each of which is further
organized as declarations followed by executable statements. An object file is
a sequence of bytes organized into blocks understandable by the system’s linker.
An executable file is a series of code sections that the loader can bring into
memory and execute.
2 File Attributes
Name: The symbolic file name is the
only information kept in human readable form.
unique tag, usually a number identifies the file within the file system.
It is the non-human readable name for the file.
Type: This information is needed for
those systems that support different types.
Location: This information is a
pointer to a device and to the location of the file on that device.
Size: The current size of the file (in
bytes, words or blocks)and possibly the maximum allowed size are
included in this attribute.
information determines who can do reading, writing, executing and so on.
Time, date and user identification: This
information may be kept for creation, last modification and last use.
These data can be useful for protection, security and usage monitoring.
3 File Operations
v Reading a
within a file
4 File Types