Ubuntu Manpage: g.message - Prints a message, warning, progress info, or fatal error in the GRASS way.

NAME

       g.message  - Prints a message, warning, progress info, or fatal error in the GRASS way.
       This module should be used in scripts for messages served to user.

KEYWORDS

       general, scripts

SYNOPSIS

       g.message
       g.message help
       g.message [-wedpiv] message=string  [debug=integer]   [--verbose]  [--quiet]

   Flags:
       -w
           Print message as warning

       -e
           Print message as fatal error

       -d
           Print message as debug message

       -p
           Print message as progress info

       -i
           Print message in all but full quiet mode

       -v
           Print message only in verbose mode

       --verbose
           Verbose module output

       --quiet
           Quiet module output

   Parameters:
       message=string
           Text of the message to be printed

       debug=integer
           Level to use for debug messages
           Options: 0-5
           Default: 1

DESCRIPTION

       This  program  is  to be used in shell/perl/python scripts, so the author does not need to
       use the echo program. The advantage of g.message is that it  formats  messages  just  like
       other  GRASS  modules do and that its functionality is influenced by the GRASS_VERBOSE and
       GRASS_MESSAGE_FORMAT environment variables.

       The program can be used for standard informative messages as well as  warnings  (-w  flag)
       and  fatal  errors  (-e flag). For debugging purposes, the -d flag will cause g.message to
       print a debugging message at the given level.

NOTES

Messages containing "=" must use the full message= syntax so the parser doesn't get
confused.

If you want a long message (multi-line) to be dealt with as a single paragraph, use a
single call to g.message with text split in the script using the backslash as the last
character. (In shell scripts don't close the "quote")

A blank line may be obtained with: g.message ""

Redundant whitespace will be stripped away.

It's advisable to single quote the messages that are to be printed literally. It prevents
a number of characters (most notably, space and the dollar sign ’$') from being treated
specifically by the Shell.

When it is necessary to include, for example, a variable's value as part of the message,
the double quotes may be used, which do not deprive the dollar sign of its special
variable-expansion powers.

While it is known that the interactive Bash instances may treat the exclamation mark '!'
character specifically (making single quoting of it necessary), it shouldn't be the case
for the non-interactive instances of Bash. None the less, to avoid context-based confusion
later on you are enouraged to single-quote messages that do not require $VARIABLE
expansion.

VERBOSITY LEVELS
Controlled by the "GRASS_VERBOSE" environment variable. Typically this is set using the
--quiet or --verbose command line options.

0 - only errors and warnings are printed

1 - progress messages are printed

2 - all module messages are printed

3 - additional verbose messages are printed

DEBUG LEVELS
Controlled by the "DEBUG" GRASS gisenv variable. (set with g.gisenv)
Recommended levels:

1 - message is printed once or few times per module

3 - each row (raster) or line (vector)

5 - each cell (raster) or point (vector)

AUTHOR