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[UDUNITS #LTB-717744]: ut_read_xml() behavior

Charlie,

> I found a flaw in my previous code where I passed an empty
> string ("") rather than a NULL to ut_read_xml().
> When I pass the NULL then the installed database is used and
> the UDUNITS2_XML_PATH is searched if specified.
> 
> > What does the above do on your system?
> 
> I tested your commands and get the same behavior.
> So the udunits2 executable works as expected.
> The behavior when linked to ncks operator, however, does not.
> However, there's lots of verbosity I do not understand.
> ncks is built with netCDF4 and is linked to the libudunits2.so.
> 
> Compile nco_lmt.c with
> 
> ut_sys=ut_read_xml(NULL);
> 
> and run and get
> 
> zender@virga:~$ unset UDUNITS2_XML_PATH
> zender@virga:~$ which ncks
> /home/zender/bin/LINUX/ncks
> zender@virga:~$ ldd `which ncks`
> linux-gate.so.1 =>  (0xffffe000)
> libhdf5.so.1 => /usr/local/netcdf4/lib/libhdf5.so.1 (0x4001d000)
> libhdf5_hl.so.0 => /usr/local/netcdf4/lib/libhdf5_hl.so.0
> (0x4051c000)
> libudunits2.so.0 => /usr/local/lib/libudunits2.so.0 (0x4054c000)
> libm.so.6 => /lib/tls/i686/cmov/libm.so.6 (0x40593000)
> libc.so.6 => /lib/tls/i686/cmov/libc.so.6 (0x405ba000)
> libz.so.1 => /usr/lib/libz.so.1 (0x406fb000)
> /lib/ld-linux.so.2 (0x40000000)
> zender@virga:~$ ncks -O -D 0 -C -H -v wvl -d wvl,'0.4 micron','0.7
> micron' -s '%3.1e' ~/nco/data/in.nc
> Definition of "kt" in "/usr/local/share/udunits2-common.xml", line 80,
> overrides prefixed-unit "1000000 kilogram"
> Definition of "microns" in "/usr/local/share/udunits2-common.xml", line
> 290, overrides prefixed-unit "1e-15 second"
> Definition of "ft" in "/usr/local/share/udunits2-common.xml", line 387,
> overrides prefixed-unit "1e-12 kilogram"
> Definition of "yd" in "/usr/local/share/udunits2-common.xml", line 395,
> overrides prefixed-unit "8.64e-20 second"
> Definition of "pt" in "/usr/local/share/udunits2-common.xml", line 616,
> overrides prefixed-unit "1e-09 kilogram"
> Definition of "at" in "/usr/local/share/udunits2-common.xml", line 1013,
> overrides prefixed-unit "1e-15 kilogram"
> Definition of "ph" in "/usr/local/share/udunits2-common.xml", line 1531,
> overrides prefixed-unit "3.6e-09 second"
> Definition of "nt" in "/usr/local/share/udunits2-common.xml", line 1538,
> overrides prefixed-unit "1e-06 kilogram"
> Definition of "kt" in "/usr/local/share/udunits2-common.xml", line 80,
> overrides prefixed-unit "1000000 kilogram"
> Definition of "microns" in "/usr/local/share/udunits2-common.xml", line
> 290, overrides prefixed-unit "1e-15 second"
> Definition of "ft" in "/usr/local/share/udunits2-common.xml", line 387,
> overrides prefixed-unit "1e-12 kilogram"
> Definition of "yd" in "/usr/local/share/udunits2-common.xml", line 395,
> overrides prefixed-unit "8.64e-20 second"
> Definition of "pt" in "/usr/local/share/udunits2-common.xml", line 616,
> overrides prefixed-unit "1e-09 kilogram"
> Definition of "at" in "/usr/local/share/udunits2-common.xml", line 1013,
> overrides prefixed-unit "1e-15 kilogram"
> Definition of "ph" in "/usr/local/share/udunits2-common.xml", line 1531,
> overrides prefixed-unit "3.6e-09 second"
> Definition of "nt" in "/usr/local/share/udunits2-common.xml", line 1538,
> overrides prefixed-unit "1e-06 kilogram"
> 5.0e-07
> 
> That 5.0e-07 is the right answer, which is good.
> But how do I lose the verbosity about "overrides prefixed-unit"?

Printing "override" messages to the standard error stream is
the default for the UDUNITS-2 library.  You can override the
default like this:

ut_set_error_message_handler(ut_ignore);
unitSystem = ut_read_xml(NULL);
ut_set_error_message_handler(ut_write_to_stderr);

> Thanks,
> Charlie
> --
> Charlie Zender, Department of Earth System Science, UC Irvine
> Visiting LGGE until 20080715: Voice: 011+33+476+824236
> Laboratoire de Glaciologie et Geophysique de l'Environnement
> BP 96, 54 rue Moliere, 38402 Saint Martin d'Heres Cedex, France

Regards,
Steve Emmerson

Ticket Details
===================
Ticket ID: LTB-717744
Department: Support UDUNITS
Priority: Emergency
Status: Closed