# -*- coding: utf-8 -*-
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"""Capture stdout output from a program and save it to a file.

  % python redirect.py out.txt echo foo
  % cat out.txt
  foo

This is essentially identical to 'echo foo > out.txt' but the script
can be used in platforms without a Unix shell (i.e. windows).
"""

import subprocess
import sys


def main():
  """The main function."""
  # Delete the self program name (i.e. redirect.py).
  sys.argv.pop(0)
  # The first parameter is the output file name.
  output_file_name = sys.argv.pop(0)
  # Rest are the target program name and the parameters, but we special
  # case if the target program name ends with '.py'
  if sys.argv[0].endswith('.py'):
    sys.argv.insert(0, sys.executable)  # Inject the python interpreter path.
  try:
    process = subprocess.Popen(sys.argv, stdout=subprocess.PIPE)
  except:
    print('==========')
    print(' ERROR: %s' % ' '.join(sys.argv))
    print('==========')
    raise
  (stdout_content, _) = process.communicate()
  # Write the stdout content to the output file.
  with open(output_file_name, 'wb') as output_file:
    output_file.write(stdout_content)
  return process.wait()

if __name__ == '__main__':
  sys.exit(main())
