On Wed, Aug 19, 2009 at 11:26 AM, Michaël
Dugaleix<[email protected]> wrote:
> Is there any risk in reading from a file and writing into the same one
> ('pipe (...) < myFile | ... | > myFile') ?
> I mean : May my original file be corrupted ?
> Supposing that :
> - there's no bug in my OS (z/VM)
> - there's no bug in CMS Pipelines (sorry, no offense meant ...)
As "pipe ahelp >mdisk" says, CMS Pipelines will write the data to a
new utility file. After completion the old one is erased and the new
file renamed (when SFS, look at PIPE ahelp configvars)
There's also another possible problem:
- there's a bug in your plumbing ;-)
The neat thing with "commit levels" in CMS Pipelines makes sure that
all things are ready to run before erasing your existing file (for
example when you have a syntax error in the pipeline).
So suppose you wanted to go through a list and drop all entries that
are expired, you can certainly do that. Obviously CMS Pipelines does
not protect you from perfect pipes that just don't do the right thing
(like forgetting to handle the start of the year in your comparison).
But chances are that when you coded in REXX a check on return code
etc, you would have lost your data too.
Rob
PS Be aware that when the pipeline does not produce any records, the
file is not erased. If you want that, you can add "strliteral //" in
the path (and use the "disk" stage rather than "<" when reading the
input)
