Scripting

2013-07-02T22:33:50Z

⚠️CENTSOARER: VEBOSE for VERBOSE

== Scripting ==

=== General ===

* See the {{cmd|g.parser}} module help page. It's an easy way to make your script look and act like a GRASS module, including creating a GUI and help page template for it automatically.

* There are a number of other:{{cmd|general}} g.* modules which are specifically useful for scripting use.

==== Verbosity level ====

Use the "--quiet" (alias --q) and "--verbose" (alias --v) command line arguments to make the script produce more or less messages and info like percent done. This works for almost all modules. The big exception to that is {{cmd|r.mapcalc}} which doesn't use the standard parser in GRASS 6 (in GRASS 7 it does).

In GRASS 6, for r.mapcalc, or if you want to set a blanket --quiet directive for the whole script, you can set the GRASS_VERBOSE environmental variable. Python's os module has a putenv() function to do that.

These are the levels you can use:
(from lib/gis/verbose.c)
0 - module should print nothing but errors and warnings (G_fatal_error,
G_warning) Triggered by "--q" or "--quiet".
1 - module will print progress information (G_percent)
2 - module will print all messages (G_message) [default level]
3 - module will be very verbose. Triggered by "--v" or "--verbose".

"--quiet" will set the level to 0.

shell script example
# for everything that follows
GRASS_VERBOSE=1
export GRASS_VERBOSE

# override for just one module
GRASS_VERBOSE=0 \
r.mapcalc "only_set = for_this_process"

Another nice thing about using the environmental variable method is that it is silently ignored for earlier versions of GRASS. For earlier versions (<6.2.x) of GRASS an error happens when "--quiet" isn't recognized as a valid command line option.

see "Verbosity levels" on the [[Development_Specs]] page.

The advantage of these methods versus sending all stderr to /dev/null is that
warning and error messages are not lost, making prototyping and debugging a
whole lot easier.

=== Shell scripts ===

See the [http://grass.osgeo.org/grass64/source/snapshot/SUBMITTING_SCRIPTS SUBMITTING_SCRIPTS] file for some tips.

See the existing GRASS scripts in the scripts/ directory for examples of using tempfiles, etc.

Newer versions of Ubuntu use Dash as the default /bin/sh, so don't assume that sh will handle Bashisms.

* [[GRASS_and_Shell|Running GRASS as a batch job]]
* [[Script_portability|Script portability]]

=== Tcl/Tk ===

See the [http://grass.osgeo.org/grass64/source/snapshot/SUBMITTING_TCLTK SUBMITTING_TCLTK] file for some tips.

=== Python ===

* See the [[GRASS and Python]] page

{{Python}}

GRASS-Wiki - User contributions [en]

Scripting