Step-by-step guide
You can use the grib_dump command with the "-D" option:
% grib_dump -D my.index
And the output will look something like this:
--- grib_index_build: processing data/tigge_cf_ecmwf.grib2 --- grib_index_build: processing data/tigge_af_ecmwf.grib2 --- grib_index_build: keys included in the index file idx: --- mars.date, mars.stream, mars.type, mars.step, mars.param, mars.levtype, mars.levelist, mars.number --- mars.date = { 20070122, 20060630, 20060623, 20060811, 20060619 } --- mars.stream = { enfo, oper } --- mars.type = { cf, fc } --- mars.step = { 96, 0 } --- mars.param = { 179, 3, 60, 260210, 235, 228141, 133, 189, 168, 121, 122, 167, 147, 176, 177, 134 } --- mars.levtype = { sfc, pl, pv, pt } --- mars.levelist = { undef, 925, 2, 320 } --- mars.number = { 0, undef } --- 83 messages indexed