[GRASS-user] Re: grass-user Digest, Vol 65, Issue 49

Glynn Clements glynn at gclements.plus.com
Tue Sep 27 17:39:54 EDT 2011

Alexander Muriy wrote:

> And r.mapcalc expression is without any quotes like r.mapcalc "na_dem_sub_20
> = na_dem_input - 20" or r.mapcalc 'na_dem_sub_20 = na_dem_input - 20'

In 6.x, the quotes are optional; in 7.0, they're required.

For forward compatibility:

1. The expression should be quoted.
2. There should be a space before the first "=" in the expression.

The reason for the change is that, in 7.0, r.mapcalc uses the GRASS
command-line parser, for consistency with other modules:

     r.mapcalc [expression=string] [file=name] [--overwrite] [--verbose] [--quiet]

The expression= option is the first (i.e. default) option, so the
"expression=" can be omitted, but the expression itself must be a
single argument (i.e. quoted), and must not resemble the "option=..." 
form used for non-default options (hence the requirement for a space
before the first "=").

Glynn Clements <glynn at gclements.plus.com>

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