Using 'gdalwarp' in Python script for Grass

I'm writing a Python script that aims to re-project various LANDSAT tiles into a common projection and then import the tiles into Grass. The script at present is shown below:

#!/usr/bin/python

import os
import sys

import glob
import grass.script as grass

def import_tifs(dirpath):
    for dirpath, dirname, filenames in os.walk(dirpath):
        for tile in filenames:
        if tile.upper().endswith('.TIF'):
                full_path = os.path.join(dirpath, tile)     
                name = os.path.splitext(tile)[0]        
        rename = name[:-4] + '.' + name[-2]

        new_path = os.path.join(dirpath, rename)
        re_project = 'EPSG:32643'
                grass.message('Importing %s -> %s@%s...' % (tile, name, dirpath))               
        grass.run_command('gdalwarp',
                  '-t_srs',
                  re_project,
                  full_path,
                  new_path)
                grass.run_command('r.in.gdal',
                                  flags = 'e',

                                  input = full_path,
                                  output = name,
                                  quiet = True,
                                  overwrite = True)

def main():                                 
    if len(sys.argv) == 1:                          
        for directory in filter(os.path.isdir, os.listdir(os.getcwd())):
            import_tifs(directory)
    else:

        import_tifs(sys.argv[1])           
if __name__ == "__main__":
   main()

I'm having real trouble using the 'gdalwarp' command to reproject the LANDSAT tiles. I keep getting the following error:

Traceback (most recent call last):
  File "C:/Users/Simon/Documents/import_landsat3.py", line
76, in 
    main()
  File "C:/Users/Simon/Documents/import_landsat3.py", line

73, in main
    import_tifs(sys.argv[1])
  File "C:/Users/Simon/Documents/import_landsat3.py", line
31, in import_tifs
    new_path)
  File "C:\GRASS64\etc\python\grass\script\core.py", line
189, in run_command
    ps = start_command(*args, **kwargs)
  File "C:\GRASS64\etc\python\grass\script\core.py", line
167, in start_command

    args = make_command(prog, flags, overwrite, quiet,
verbose, **options)
  File "C:\GRASS64\etc\python\grass\script\core.py", line
124, in make_command
    raise ScriptError("'-' is not a valid flag")
grass.script.core.ScriptError: "'-' is not a valid flag"

I'm assuming this is related to '-t_srs' but I haven't been able to work out a way around the problem - can anyone suggest how to do this?

Many thanks.

Answer

Have you tried calling gdalwarp using os.sys? Check this post for more details on the topic.