Re: [rdiff-backup-users] What filename characters does Mac OS X support?

[Kevin Horton]

On 20 Oct 2005, at 21:26, Ben Escoto wrote:

> I'm trying to make rdiff-backup a little friendlier on Mac OS X now.
> Does anyone know offhand what characters are allowable in a Mac OS X
> filename?
>
> I'm asking because I need to figure out exactly when we don't need to
> quote characters.  As long as the source directory is non-empty (and
> has a filename that has a letter in it), then we can tell whether that
> directory is case-sensitive.  But it's harder to tell whether or not a
> source (and thus read-only) directory supports characters like a colon
> or a backslash.
>
> So if Mac OS X supports everything except case sensitivity (and '/',
> and NULL).  But if there is other support missing things could become
> more complicated.

At the GUI level, it seems that OS X allows any character except a  
colon and NULL.  "/" characters are legal, but the GUI translates  
them to ":" behind the scenes at the unix level.  So a file named  
"crazy/name.txt" at the GUI level is actually named "crazy:name.txt"  
at the unix level.

This strange system of translating "/" to ":" is due to the fact that  
OS 9 and earlier used ":" as the path specifier - the equivalent of  
"/" in unix, or "\" in DOS.  "/" was legal in filenames in OS 9.   
When OS X came along, they needed a way to handle users who had  
legacy files with a "/" in them, so they came up with this scheme to  
translate them to ":".

At the unix level where rdiff-backup works, every character appears  
to be legal except "/" and NULL.

The above info is based on what the OS X Help system says, and what I  
can find on Google.  It is not guaranteed to be 100% complete, but I  
am 99.9% sure it is good info.

http://docs.info.apple.com/article.html?path=Mac/10.4/en/mh552.html
http://lists.seas.upenn.edu/pipermail/unison-hackers/2005-March/ 
000006.html

Kevin Horton
Ottawa, Canada