Options

Each option on the wgrib2 command line is translated into a subroutine call by wgrib2. In some sense, the command line is actually a simple program as it describes the order of the subroutine calls. As with most languages, the order is important and subroutines can be called more than once. Wgrib2 handles the subroutine calls differently from most languages. First, there is an init phase, each subroutine is called in order with mode = INIT. This allows the subroutines to do the needed initialization procedures such as opening files and initializing variables. Then there is the data phase. Each subroutine is called in order with a pointer to the current grib message. Finally there is the cleanup phase. Each subroutine is called with mode = CLEANUP.

Wgrib2 has four classes of options: init, inv, out and misc.

type	when run	uses
init	run only on init phase	used for setting flags
inv	run on init, data and cleanup phases	writes to the stdout (inventory)
out	run on init, data and cleanup phases	writes to files
misc	run on init, data and cleanup phases	none of the above