Shell/GRASS: Exit loop upon raster value

Question

I am running a loop from a shell script in GRASS GIS 7. Basically, values are subtracted from a raster in each step. I want the script to stop/exit if any of the raster values is 0 or less. Is there a simple if(,,) command to accomplish this?

Answer 1

Don't know which shell language you are using but basically I'd use r.info -r inside an if block to get the value range for the raster. If you find that your raster has values 0 or less, you the use break or continue depending on your need, to exit the loop and carry on.

Break and Continue manual page of bash.

http://tldp.org/LDP/Bash-Beginners-Guide/html/sect_09_05.html

Answer 2

Thanks! Solved it: I added a if-crierion. If below 0, then 1, else 0. In each step I have Octave (runs in the background via executable) calculate the sum of the raster values. Shell/GRASS reads the value: while [ $X -lt 1 ] do [...]

as soon as sum >=1, the loop stops.