View All Pages

Data File Contents (cwinfo)

Once you start a terminal session, change directories to where you saved the example data files and type:

cwinfo example_viirs_chlor_sep_2022.nc

You should see the file contents printed:

Terminal window showing output of cwinfo command 

The cwinfo tool lists global file attributes and the data variables in the file in a human-readable format.  The tool also has a useful mode that prints the coordinates of the edges of the data, and its resolution:

cwinfo --transform example_goci2_reflect_jan_2023.hdf

You should see the following:

Terminal window showing output of cwinfo command with --transform option

You'll notice throughout the command line examples that all tools have a similar behaviour:

  • An input file name and possibly output file name are required.
  • There are optional parameters, both in a long form double-dash like --transform and a short form single-dash like -t .
  • Some optional parameters take values, for example --locFormat DDMM  in cwinfo, where as others are just switches like --verbose.
  • If you type -h after the command it will print a usage summary
  • If you type --version after the command it will print a version number, for example cwutils 3.7.1.1230 20220718_175207

Bonus exercises:

  • Try typing cwtools (in version 3.8.0 and later) at the command line to list all the tools and their function.  This is useful if you forget the tool names.
  • Look at the cwinfo manual page, either in the user's guide or the Unix man pages.
  • Find out how to make cwinfo print out its progress when the tool is trying to identify the file format.