Stdout¶

Suppress stdout and stderr¶

https://github.com/facebook/prophet/issues/223

stdin/stdout are global variables, shared between threads, and so are file descriptors.

This method

• works for stdout and stderr from c as well

• will fail within multi-thread tasks (without output or with unexpected outputs)

  class SUPPRESS_STDOUT_STDERR(object):
      '''
      A context manager for doing a "deep suppression" of stdout and stderr in
      Python, i.e. will suppress all print, even if the print originates in a
      compiled C/Fortran sub-function.
         This will not suppress raised exceptions, since exceptions are printed
      to stderr just before a script exits, and after the context manager has
      exited (at least, I think that is why it lets exceptions through).
      '''
      def __init__(self):
          # Open a pair of null files
          self.null_fds = [os.open(os.devnull, os.O_RDWR) for x in range(2)]
          # Save the actual stdout (1) and stderr (2) file descriptors.
          self.save_fds = [os.dup(1), os.dup(2)]
  
      def __enter__(self):
          # Assign the null pointers to stdout and stderr.
          os.dup2(self.null_fds[0], 1)
          os.dup2(self.null_fds[1], 2)
          # https://stackoverflow.com/questions/66784941/dup2-and-pipe-shenanigans-with-python-and-windows
          if sys.platform == 'win32':
              sys.stdout.write = lambda z: os.write(
                  sys.stdout.fileno(),
                  z.encode() if hasattr(z, 'encode') else z
              )
  
      def __exit__(self, *_):
          # Re-assign the real stdout/stderr back to (1) and (2)
          os.dup2(self.save_fds[0], 1)
          os.dup2(self.save_fds[1], 2)
          # Close the null files
          for fd in self.null_fds + self.save_fds:
              os.close(fd)
  

https://medium.com/swlh/python-recipes-suppress-stdout-and-stderr-messages-9141ef4b1373

redirect stdout and stderr to file¶

https://eli.thegreenplace.net/2015/redirecting-all-kinds-of-stdout-in-python/

https://dzone.com/articles/redirecting-all-kinds-stdout

https://devpress.csdn.net/python/62fd8a92c677032930803e01.html