MECH 2301 Lecture Notes - Lecture 17: Data File, Carriage Return, Delimiter
20 May 2018
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MECH 2301 Lecture 17 Notes
Introduction
Manipulate the Directory
• Most user commands to the operating system are actually requests to the file manager.
• Consider the operations on a file that a file management system would perform.
• These operations can be divided into three different categories of operations
• Those that work on the entire file, those that operate on data within the file
• Those that actually manipulate the directory of the file without actually accessing the
file itself
• The examples of operations that work on the file as a whole are likely to be familiar to
you as a user
• Copy a file
• Load and execute a (program) file
• Move a file (assuming the move is to a different device)
• List or print a file
• Load a file into memory
• Store a file from memory
• Compile or assemble a file
• Append data from memory to a file Fundamental to every file manager, both stream-
and record-based, is the ability to manipulate the data within the file itself.
• The file manager provides a basic set of operations that are used for this purpose.
• These operations probably seem less familiar to you as a user.
• That is because they are usually requested by a program, rather than directly by the
user.
• Open a file for reading or writing.
• This procedure provides a buffer for holding the data as it is read or written and also
creates a pointer that moves through the data as it is read or written.
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