Re: [netcdfgroup] streaming ncdump?

• To: netcdfgroup@xxxxxxxxxxxxxxxx, Tom Roche <Tom_Roche@xxxxxxxxx>
• Subject: Re: [netcdfgroup] streaming ncdump?
• From: Russ Rew <russ@xxxxxxxxxxxxxxxx>
• Date: Thu, 29 Mar 2012 14:31:05 -0600

Hi Tom,

> This may be a *x question, or just totally wrongheaded, but thought
> I'd ask: can one stream to netCDF tools (e.g., `ncdump`)? Why I ask:
> 
> I've got data on one host which has netCDF configuration problems.
> I've got another host on the same LAN which does not. So I thought I'd
> 
> me@goodNetCDF:~ $ ssh badNetCDF 'cat /path/to/netCDF/data' | ncdump -h
> 
> but that failed. Yes, I know I could just copy the file to /tmp :-)
> but I thought I'd ask.

The problem is that netCDF is implemented in terms of the lseek(2)
system function, to seek directly to a specified offset before reading
or writing.  If you try to seek on a pipe, such as stdin, Unix returns
the error ESPIPE.

NetCDF-Java has defined an experimental streaming protocol that could be
applied to your use case:

  http://www.unidata.ucar.edu/software/netcdf-java/stream/NcStream.html

and there's some support for ncstream in the C library (see libcdmr
directory), but the utilities ncdump and nccopy haven't been adapted to
make use of it.

--Russ

• References:
  • [netcdfgroup] streaming ncdump?
    • From: Tom Roche