[gpfsug-discuss] Question about Policies - using mmapplypolicy/EXTERNAL LIST/mmxargs

[Jonathan Buzzard]

On 29/12/2019 14:24, Marc A Kaplan wrote:
> Correct, you may need to use similar parsing/quoting techniques in your 
> renaming scripts.
> 0
> Just remember, in Unix/Posix/Linux the only 2 special characters/codes 
> in path names are '/' and \0. The former delimits directories and the 
> latter marks the end of the string.
> And technically the latter isn't ever in a path name, it's only used by 
> system APIs to mark the end of a string that is the pathname argument.
>i

I am not sure even that is entirely true. Certainly MacOS X in the past 
would allow '/' in file names. You find this out when a MacOS user tries 
to migrate their files to a SMB based file server and the process trips 
up because they have named a whole bunch of files in the format

     "My Results 30/12/2019.txt"

At this juncture I note that MacOS is certified Unix :-)

I think it is more a file system limitation than anything else. I wonder 
what happens when you mount a HFS+ file system with such named files on 
Linux... I would at this point note that the vast majority of "wacky" 
file names originate from MacOS (both Classic and X) users.

Also while you are otherwise technically correct about what is allowed 
in a file name just try creating a file name with a newline character in 
it using either a GUI tool or the command line. You have to be really 
determined to achieve it. I have also seen \007 in a file name, I mean 
really.

Our training for new HPC users has a section covering file names which 
includes advising users not to use "wacky" characters in them as we 
don't guarantee their continued survival. That is if we do something on 
the file system and they get "lost" as a result it's your own fault.

In my view restricting yourself to the following is entirely sensible

https://docs.microsoft.com/en-us/rest/api/storageservices/naming-and-referencing-shares--directories--files--and-metadata

Also while Unix is generally case sensitive creating files that would 
clash if accessed case insensitive is really dumb and should be avoided. 
Again, if it causes you problems in future, it sucks to be you.


JAB.

-- 
Jonathan A. Buzzard                         Tel: +44141-5483420
HPC System Administrator, ARCHIE-WeSt.
University of Strathclyde, John Anderson Building, Glasgow. G4 0NG