How to write to stdout AND to log file simultaneously with Popen?

by

You can use a pipe to read the data from the program’s stdout and write it to all the places you want:

import sys
import subprocess

logfile = open('logfile', 'w')
proc=subprocess.Popen(['cat', 'file'], stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
for line in proc.stdout:
    sys.stdout.write(line)
    logfile.write(line)
proc.wait()

UPDATE

In python 3, the universal_newlines parameter controls how pipes are used. If False, pipe reads return bytes objects and may need to be decoded (e.g., line.decode('utf-8')) to get a string. If True, python does the decode for you

Changed in version 3.3: When universal_newlines is True, the class uses the encoding locale.getpreferredencoding(False) instead of locale.getpreferredencoding(). See the io.TextIOWrapper class for more information on this change.

More Related Contents:

  1. Python subprocess/Popen with a modified environment
  2. How to use subprocess popen Python [duplicate]
  3. Subprocess.Popen: cloning stdout and stderr both to terminal and variables
  4. Python popen command. Wait until the command is finished
  5. How can I specify working directory for popen
  6. Intercepting stdout of a subprocess while it is running
  7. Python subprocess.Popen() error (No such file or directory)
  8. Popen with conflicting executable/path
  9. How do I get ‘real-time’ information back from a subprocess.Popen in python (2.5)
  10. subprocess.Popen() error (No such file or directory) when calling command with arguments as a string
  11. How do I get all of the output from my .exe using subprocess and Popen?
  12. link several Popen commands with pipes
  13. Is it possible to run function in a subprocess without threading or writing a separate file/script.
  14. Python subprocess and user interaction
  15. Keep a subprocess alive and keep giving it commands? Python
  16. Launch a shell command with in a python script, wait for the termination and return to the script
  17. How to get output from subprocess.Popen(). proc.stdout.readline() blocks, no data prints out
  18. How to run a background process and do *not* wait?
  19. real time subprocess.Popen via stdout and PIPE
  20. What’s the difference between subprocess Popen and call (how can I use them)?
  21. python subprocess Popen environment PATH?
  22. How do I eliminate Windows consoles from spawned processes in Python (2.7)? [duplicate]
  23. How can I specify working directory for a subprocess
  24. Bash style process substitution with Python’s Popen
  25. Why does subprocess.Popen() with shell=True work differently on Linux vs Windows?
  26. How to do multiple arguments with Python Popen?
  27. subprocess.wait() not waiting for Popen process to finish (when using threads)?
  28. Opening a process with Popen and getting the PID
  29. subprocess.Popen in different console
  30. What is the subprocess.Popen max length of the args parameter?

Leave a Comment