[GRASSGUI] Re: grassgui Digest, Vol 4, Issue 6

[Glynn Clements]

Michael Barton wrote:

> The file= option would be most useful for users directly accessing the
> command. 
> 
> > An alternative is to add stdin= and stdout= pseudo-options to the
> > module's GUI dialog, so that the user can redirect stdin/stdout of any
> > command from/to a file. This can be done in addition to a file= option
> > for modules where it would be useful.
> > 
> 
> Within a GUI environment, I'd like to be able to send these (and some other
> commands a set of rules stored in a variable, so that I don't have to save
> them to a tmp file and do the equivalent of...
> 
> cat [file] | r.recode input=[map] output=[map]
> 
> I'd rather do the equivalent of ...
> 
> echo $rules > r.recode input=[map] output=[map]

This is meaningless; the RHS of the ">" operator has to be a filename.

If you don't want to use a temporary file, use stdin, i.e.:

	echo "$rules" | r.recode input=[map] output=[map]

The other alternative would be to pass the rules as an argument, e.g.:

	r.recode input=[map] output=[map] rules="`echo $rules`"

However, a long list of rules could easily overflow the maximum length
of a command line (which may be as low as 1Kb on some platforms).

-- 
Glynn Clements <glynn at gclements.plus.com>