[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[LDM #AUZ-681434]: LDM Partial Files

This archive contains answers to questions sent to Unidata support through mid-2025. Note that the archive is no longer being updated. We provide the archive for reference; many of the answers presented here remain technically correct, even if somewhat outdated. For the most up-to-date information on the use of NSF Unidata software and data services, please consult the Software Documentation first.

  • Subject: [LDM #AUZ-681434]: LDM Partial Files
  • Date: Thu, 19 Sep 2019 09:58:03 -0600
Hi Walter,

> Does ldm use some mechanism to prevent users from reading files before they
> are finished being written? I'm thinking of something like *.*(dot) files
> or changing file permissions.
> I would give you more information but I am a novice user and not sure what
> you might need to know about our usage of ldm.

LDM data-products are processed locally via the pqact(1) utility, which won't 
act on a product until it has been completely received. If the utility is 
writing the product to a file, then it's possible that another process could 
read an incomplete product from the file. The way to obviate this would be to 
either pipe the product to a decoder (instead of filing the product) or to act 
on the file *after* it has been closed. For example, the pqact(1) configuration 
file could contain

    <feedtype> <pattern> FILE -overwrite -close <pathname>
    <feedtype> <pattern> EXEC <program> <pathname>

More information on the LDM can be found at 
<https://www.unidata.ucar.edu/software/ldm/ldm-current/basics/index.html>.

Please feel free to contact us if you have further questions.

Regards,
Steve Emmerson

Ticket Details
===================
Ticket ID: AUZ-681434
Department: Support LDM
Priority: Normal
Status: Closed
===================
NOTE: All email exchanges with Unidata User Support are recorded in the Unidata 
inquiry tracking system and then made publicly available through the web.  If 
you do not want to have your interactions made available in this way, you must 
let us know in each email you send to us.