ncdump [-c] [-h] [-v var1,...] [-b lang] [-f
lang] [-l len]
[-n name] [-d f_digits[,d_digits]]
fileWhere:
-c Show the values of
coordinate variables (variables that
are also dimensions) as well as the declarations of all
dimensions, variables, and attribute values. Data
values of non-coordinate variables are not included in
the output. This is the most suitable option to use
for a brief look at the structure and contents of a
netCDF file.
-h Show only the
header
information in the output, that is
the declarations of dimensions, variables, and attributes but no data values for any variables. The output
is identical to using the -c option except
that the
values of coordinate variables are not included. (At
most one of -c or -h options may be
present.)
-v
var1,...,varn
-c
or -h options, is to include data values for
all variables in the output.
-b lang
lang begins with
C or c, then C
language conventions will be used (zero-based indices,
last dimension varying fastest). If lang
begins
with
F or f, then Fortran language
conventions will be
used (one-based indices, first dimension varying
fastest). In either case, the data will be presented
in the same order; only the annotations will differ.
This option is useful for browsing through large
volumes of multidimensional data.
-f lang
lang
begins with C or c, then C
language conventions
will be used (zero-based indices, last dimension varying
fastest). If lang begins with F or
f, then
Fortran language conventions will be used (one-based
indices, first dimension varying fastest). In either
case, the data will be presented in the same order;
only the annotations will differ. This option may be
useful for piping data into other filters, since each
data value appears on a separate line, fully
identified.
-l len
-n name
ncgen -b
in generating a default netCDF file name. By
default, ncdump constructs this name from the
last component of the pathname of the input netCDF file by
stripping off any extension it has. Use the -n
option
to specify a different name. Although the output file
name used by ncgen -b
can be specified, it may be wise
to have ncdump change the default name to avoid
inadvertantly overwriting a valuable netCDF file when using
ncdump, editing the resulting CDL file, and using
ncgen
-b to generate a new netCDF file from the edited
CDL
file.
-d float_digits[,double_digits]
float_digits significant digits. If
double_digits is
also specified, double-precision values will be
displayed with that many significant digits. If a
variable has a `C_format' attribute, that overrides any
specified floating-point default. In the absence of
any -d specifications, floating-point and
double-
precision data are displayed with 7 and 15 significant
digits respectively. CDL files can be made smaller if
less precision is required. If both floating-point and
double-presision precisions are specified, the two
values must appear separated by a comma (no blanks) as
a single argument to the command. If you really want
every last bit of precision from the netCDF file
represented in the CDL file for all possible floating-
point values, you will have to specify this with -d
9,17.ncdump generates an ASCII representation of a
specified
netCDF file on standard output. The ASCII representation is
in a form called CDL (``network Common Data form
Language'')
that can be viewed, edited, or serve as input to ncgen.
ncgen is a companion program
that can generate a binary
netCDF file from a CDL file. Hence ncgen and ncdump can
be
used as inverses to transform the data representation
between binary and ASCII representations. See ncgen for a
description of CDL and netCDF representations.
ncdump defines a default format used for each type of
netCDF
data, but this can be changed if a `C_format' attribute is
defined for a netCDF variable. In this case, ncdump
will
use the `C_format' attribute to format each value. For example,
if floating-point data for the netCDF variable Z is
known to be accurate to only three significant digits, it
would be appropriate to use the variable attribute
Z:C_format = "%.3g"
ncdump may also be used as a simple browser for netCDF
data
files, to display the dimension names and sizes; variable
names, types, and shapes; attribute names and values; and
optionally, the values of data for all variables or selected
variables in a netCDF file.
foo.nc:
ncdump -c foo.nc
foo.nc, using C-style indexing for
the
annotations:
ncdump -b c foo.nc > foo.cdl
uwind and
vwind from
the netCDF file foo.nc, and show the floating-point
data
with only three significant digits of precision:
ncdump -v uwind,vwind -d 3 foo.nc
omega, using Fortran
conventions for indices, and changing the netCDF dataset name in
the resulting CDL file to omega:
ncdump -v omega -f fortran -n omega foo.nc > Z.cdl