CODEWITHSUNDEEP
pythonstdoutdaemon
CrabbyPete
CrabbyPete

Reputation: 534

python-daemon not logging stdout redirection

I am using python-daemon in my code that has print statements in it. I want to send them to a file so I ran the following:

python server.py >> log.out

However, nothing goes in log.out.

Can anyone tell me what I need to do?

Thanks.

Upvotes: 5

Views: 4917

Answers (4)

Jürgen A. Erhard
Jürgen A. Erhard

Reputation: 4860

The "problem" is that python-daemon closes all file descriptors, including stdout. You either need to do what @elarson suggested or (if you want to keep the stdout redirection when starting your daemon) exclude sys.stdout from being closed by adding something like

files_preserve = [sys.stdout]

to you DaemonContext invocation.

Upvotes: 0

elarson
elarson

Reputation: 865

The DaemonContext object allows redirecting stdout/stderr/stdin when you create the object. For example:

import os
import daemon


if __name__ == '__main__':
    here = os.path.dirname(os.path.abspath(__file__))
    out = open('checking_print.log', 'w+')

    with daemon.DaemonContext(working_directory=here, stdout=out):
        for i in range(1, 1000):
            print('Counting ... %s' % i)

You should be able to cat checking_print.log and see the output from the print statements.

A good reference for the DaemonContext object is PEP 3143.

Upvotes: 6

demux
demux

Reputation: 4654

if you have an error in your code it will not be written to the file. See http://tldp.org/HOWTO/Bash-Prog-Intro-HOWTO-3.html

Try creating this file:

print 'stdout'
raise Exception('stderr')

Upvotes: -1

Christian Witts
Christian Witts

Reputation: 11585

If it's already running as a daemon you'll most likely need to force redirection of STDOUT, STDERR etc. You can read more on I/O Redirection here.

python server.py 2>log.out >&2

Upvotes: -2

Related Questions