batch processing in GRASS

Bill Brown brown at
Mon Dec 16 07:00:00 EST 1996

When GRASS writes a raster file, it is really writing to a 
tmp file, using the PID to generate a name in the user's
$LOCATION/.tmp/machinename directory.  When the file is
CLOSED, it is renamed to the cell directory, so I would
guess that the process that finishes last will overwrite
the previously generated files.

- Bill

> Hi:
>    Recently, one of my users has (inadvertently) gotten
> into the situation where multiple instances of EXACTLY
> the same GRASS job have been run in the background.
> This is on a Linux installation.  All the programs
> are working with the same region of data, which shouldn't
> be a problem, and all of them are using the same file
> for input (which is not being modified by any of the
> programs).  But what I am having problems understanding
> is how GRASS can let multiple jobs write to the same 
> file?  Doesn't GRASS grant the first program to run an
> exclusive write file lock?  Shouldn't the remaining
> GRASS programs die since they cannot get write access on
> the file?

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