File Systems Flashcards
Information stored in files must be [p] and not affected by [p] [c] and [t]. A file should only [d] when its owner explicitly [r] it.
persistent process creation termination disappear requests
There are three essential requirements for files.
Store a large amount of information
Information should survive process termination
Multiple processes must be able to access information concurrently.
A file is a type of [u]
unit
A regular file…
contains user information
Directories are…
special files for maintaining the file system
Character special files
are related to input output and used to model I/O
Block special files…
are used to model disks
Sequential allocation allows a process…
to read bytes from a start to an end point. Not good at jumping around.
Define random access files
files whose bytes and records can be read in any order
Every file has [n] and [d]
name and data
The extra information associated with a file are called its
attributes
Record length, ley position and key length are only present in files…
…that are looked up using a key.
Create() does what?
creates a file with no data.
Delete() does what?
deletes a file
Open() does what?
Allows system to fetch attributes and list of disk addresses into main memory.
Write() does what?
data is written to a file, usually at the current position.
Read() does what?
Data are read from file. Caller must specify how much.
Append() does what?
A restricted form of write. Adds to end of file.
File organisation needs to allow for [qa], [eu], [es], [sm] and [r]
quick access easy update economy of storage simple maintenence reliability
An absolute path name
is the path to the requested file from the route
A relative path name…
is used in conjunction with the working directory. path names are defined in relation to the working directory.
tree structures allow…
several file names, provided the paths are different
