Filename guidelines

[Jeff Johnson]

*INTRODUCTION*

The FHS's focus is to present a specification to which filesystems will either
comply or not comply. Due to variation in current practice, any set of hard
rules for filenames are likely to exclude some current practice, be so lax as to
not usefully promote good practice, or contain a mass of rules and exceptions.
It is a thorny issue, but an important one none the less. Although a set of
hard rules may not be practical, I think it may be useful to promote some
guidelines. With this in mind, I would like to suggest the following specific
guidelines.

*GUIDELINES*

It is suggested that, where practical, filenames:
1/ contain only the following characters:
   [a-z] [A-Z] [0-9] + - _ , . ~
2/ not start with these characters: + - ~
3/ not end with this character: .
4/ be limited to 31 characters in length
5/ are unique if case is not differentiated,
   and all non-alphanumeric characters are considered equilivant.
6/ and not be any of the following (case regardless):
   aux con com[0-9] lpt[0-9] prn

*RATIONALE*

Guidelines 1&2 are to ensure filenames are Unix shell safe. Guidelines 3,4&5
are to avoid unpredictable filename mangling on ISO 9660 CD-ROM filesystems (a
very common medium for distributing Unix files). Guideline 6 is to ensure
filenames are MS Windows safe (Unix files may well pass through MS Windows on
their way from one place to another).

--
James G