[GRASS-dev] [GRASS GIS] #2679: Drop or fix setting of Location and Mapset using environmental variables

[GRASS GIS]

#2679: Drop or fix setting of Location and Mapset using environmental variables
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 Reporter:  wenzeslaus                           |      Owner:  grass-dev@…
     Type:  defect                               |     Status:  new
 Priority:  normal                               |  Milestone:  7.1.0
Component:  Startup                              |    Version:  svn-trunk
 Keywords:  init, grass.py, interface, CLI,      |        CPU:  Unspecified
  script, batch job                              |
 Platform:  Unspecified                          |
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 The [source:grass/trunk/lib/init/grass7.html#L291 manual describes] that
 one can set Location and Mapset using system environmental variables but
 it does not work:

 {{{
 $ export GISDBASE=~/grassdata/
 $ export LOCATION_NAME=nc_spm_08_grass7_tests_2
 $ export MAPSET=landsat
 $ .../grass71 -
 Cleaning up temporary files...
 Starting GRASS GIS...
 Traceback (most recent call last):
   File ".../grass71", line 1423, in <module>
     non_interactive(args[0])
   File ".../grass71", line 586, in non_interactive
     if gisdbase and location_name and mapset:
 NameError: global name 'gisdbase' is not defined
 }}}

 I was wondering if I broke it but I get this behavior in r65235 before any
 changes I made. It actually seems that is was always broken since r37863,
 translating from Bash to Python.

 This means that nobody is using with 7 it because nobody complains. For
 now I just [source:grass/trunk/lib/init/grass.py#L783 put] `pass` in to
 that `if` branch (it will fail later).

 Also the dash used in this context seems quite strange, especially for
 GRASS. We should consider alternatives.

 In general this behavior seems useless to me, why use environmental
 variable when I can use parameter? However, it might become quite useful
 with the "exec subcommand" (#2579) for running commands inside the
 session. You would set the environment and then just call grass:

 {{{
 export GISDBASE=~/grassdata/
 export LOCATION_NAME=nc_spm_08_grass7_tests_2
 export MAPSET=landsat
 grass7 - exec g.region -p
 }}}

 Do we want to restore this behavior or it is ok to drop it?

 If we want to fix also 7.0, some copy & paste should be possible.

 PS: Either way, I won't be able to work on it right now, so if somebody
 can take over, it would be great. (It should be much easier now after the
 refactoring. There are notes in the source code about what needs to be
 done.)

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Ticket URL: <https://trac.osgeo.org/grass/ticket/2679>
GRASS GIS <http://grass.osgeo.org>