[GRASSLIST:3416] GRASS scripting question

[Thomas Adams]

I have generated 8760 (hourly) maps of radar precipitation fields that I 
need to sum to monthly (and daily) totals using r.mapcalc within a Perl 
script. I have tried *EVERYTHING* I can do with this but I keep getting 
an error related to the shell not properly handling '+'. Namely:

$cmd = "r.mapcalc ". $newmap . "=". $map1; 
system $cmd;    <--- this works just fine.

But when I try:

$cmd = "r.mapcalc ". $newmap . "=". $map1 ."+". $map2; 
system $cmd;    <--- this fails.

saying that "+map2" is an invalid command, but the "r.mapcalc 
".$newmap."=".$map1 part suceeds. I have also tried using:

$cmd = "r.mapcalc ". $newmap . "=". $map1 ."\+". $map2; 

When I try using Perl's 'join' command I get the same error.

How do I do this in a script? Obviously, at the GRASS prompt, 
interactively, r.mapcalc works for me.

Regards,
Tom

-- 
Thomas E Adams
National Weather Service
Ohio River Forecast Center
1901 South State Route 134
Wilmington, OH 45177

EMAIL:	thomas.adams at noaa.gov

VOICE:	937-383-0528
FAX:	937-383-0033