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  1. Specifying the information to display:

    Code Block
    grib_ls -p dataDate,dataTime,stepRange,shortName,typeOfLevel,level ICMGGepc8+000000

  2. Specifying the type of key (s: string, i: integer).  To output the centre as a string (default):

    Code Block
    grib_ls -p centre:s ICMGGepc8+000000

    or as an integer:

    Code Block
    grib_ls -p centre:i ICMGGepc8+000000

  3. Listing specific namespace information.  Try:

    Code Block
    grib_ls -n parameter ICMGGepc8+000000

    and

    Code Block
    grib_ls -n statistics ICMGGepc8+000000

    Other namespaces to try are time, vertical and geography.

  4. Order the output.  Try:

    Code Block
    grib_ls -B "level desc" ICMSHepc8+000000

    Compare and contrast with:

    Code Block
    grib_ls -B "level:i desc" ICMSHepc8+000000

  5. The where option:  IS

    Code Block
    grib_ls -w shortName=stl1 ICMGGepc8+000000

    IS NOT

    Code Block
    grib_ls -w shortName!=stl1 ICMGGepc8+000000

    OR

    Code Block
    grib_ls -w shortName=stl1/z ICMGGepc8+000000

    AND

    Code Block
    grib_ls -w shortName=q,level=10 ICMGGepc8+000000

  6. Specifying the step unit.  Compare the output from:

    Code Block
    grib_ls -n time ICMGGepc8+000000

    and

    Code Block
    grib_ls -s stepUnits=m -n time ICMGGepc8+000012

    The stepUnits can be set to s,m,h,3h,6h,12h,D,M,Y,10Y,30Y or C.  The result must be expressible as an integer (try setting stepUnits=D above). This is a temporary change for display purposes only !

Note

grib_ls is a tool meant mainly for interactive use.  If you want to use the tools in a shell script then take a look at grib_get instead. It works in much the same way as grib_ls but is less verbose and also fails if an error occurs.

Obtaining detailed information about a GRIB message with grib_dump

  1. To print all of the keys available for a particular GRIB message:

    Code Block
    grib_dump -w shortName=stl1 ICMGGepc8+000012

  2. To obtain a listing which is more like the WMO tables:

    Code Block
    grib_dump -O -w shortName=stl1 ICMGGepc8+000012

  3. To obtain even more detail:

    Code Block
    grib_dump -OatH -w shortName=stl1 ICMGGepc8+000012

Printing the data values

For grid point data, the grib_get_data tool prints a list of latitude, longitude and data values from one or more GRIB files. 

  1. Try

    Code Block
    grib_get_data -w shortName=z  ICMGGepc8+000000

  2. The format of the data values can be controlled with a C-style format statement.  Try:

    Code Block
    grib_get_data -w shortName=z -F"%.4f" ICMGGepc8+000000

  3. Other information can be printed along with the lat-lon-values triplet:

    Code Block
    grib_get_data -p dataDate,dataTime,stepRange -w shortName=stl1 -F"%.4f" ICMGGepc8+000000
Warning

If you need the values in a program then do not be tempted to use grib_get_data to output the information to a file and then read the file in your program.  It is more efficient to use the appropriate Fortran 90, C or Python interface to GRIB API to access the data values directly.

Using the smart copy

The structure of GRIB allows files to be simply copied and concatenated with the UNIX 'cat' command.  However, it's sometimes desirable to do something more sophisticated.  The grib_copy tool provides a way to copy only selected content from GRIB files.

 

Resources and further reading

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