RE: Formatless files

[Roger L Costello <costello@mitre.org>]

"Files in the UNIX system are formatless. That means that they are simply a string of characters or bytes. Any format imposed on the data is done by the programmer rather than by the operating system. This makes programming very easy for programmers."

"Let me contrast to other operating systems where at file creation time a programmer must specify what information will be in the file, how big the file will be, etc. Once that is done the programmer is locked into it. Having locked into that kind of file, then later it becomes impossible to put another kind of data in that file. The analogy is to try to put a legal-sized document into a letter-size file. It simply won't fit." 

[Roger: At file creation time an XML author must specify what the character encoding (charset) is. Once that is done the XML document is locked into that charset. Having locked into that kind of charset, then later it becomes impossible to put data with another kind of charset in that file. For example, if the file is created using the UTF-8 charset, then later you cannot insert data in the EBCDIC charset.]

"In the UNIX system you don't have this problem because data in files is formatless and data can be easily moved back and forth between files." 

"Formatless files in which the data consists solely of a stream of bytes that is uninterpreted by the operating simplifies life because it means that any program can process any file. When you combine this with the concept of pipelining or stream processing, it makes UNIX an extremely powerful programming tool."

Dennis Ritchie, Ken Thompson, Brian Kernighan, Catherine Ann Brooks

https://youtu.be/XvDZLjaCJuw?t=707