CODEWITHSUNDEEP
pythonfile-io
BhishanPoudel
BhishanPoudel

Reputation: 17164

Python: stdout to both console and textfile including errors

I would like to print the output of python to both console and a textfile including errors, if any.

So far my attempts are these:

Using console:

# mystdout.py
# note that it has missing ) sign
print("hello


# in the terminal:
chmod a+x mystdout.py; ./mystdout.py 2>&1 | tee output.txt
# does not print to oputut.txt if mystout.py has syntax errors

Print to file (python3):

with open('out.txt', 'a') as f:  
    print('hello world', file=f)
    # this does not print to console, only to the file

Defining a class called "Tee"

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# Author    : Bhishan Poudel
# Date      : Jul 12, 2016


# Imports
import sys
import subprocess

##=============================================================================
class Tee(object):
    def __init__(self, *files):
        self.files = files
    def write(self, obj):
        for f in self.files:
            f.write(obj)
            f.flush() 
    def flush(self) :
        for f in self.files:
            f.flush()

f = open('out.txt', 'w')
original = sys.stdout
sys.stdout = Tee(sys.stdout, f)
##=============================================================================
print('This works good, prints all the output to both console and to a file')
print("This does not print output to file in case of syntax errors")
print("This does not print output of subprocess.call")

Question Suppose I have an executable (from C program that prints hello)

subprocess.call('./hello')
# How to print output of this executable to both console and outputfile?

Note: Code to produce executable hello

// gcc -o hello hello.c
#include<stdio.h>

int main() {
    printf("hello\n");
return 0; }

Related links:
How to redirect 'print' output to a file using python?
http://linux.byexamples.com/archives/349/how-to-redirect-output-to-a-file-as-well-as-display-it-out/
Output on the console and file using python

Upvotes: 3

Views: 2524

Answers (3)

BhishanPoudel
BhishanPoudel

Reputation: 17164

I am using bash 3.2.53. Unfortunately the solution by Pierre does not worked for me. And solution referred by grundic was too complicated for me.

So, I came up with the easy solution:
When the python run without errors, This method worked for me:

python3 a.py | tee aout.txt

# to test other example
echo hello this is a test | tee hello.txt

# Like this it works for every commands.

Upvotes: 0

Pierre
Pierre

Reputation: 6237

If you are using bash (minimum version 4), you can run: ./mystdout |& tee output.txt. Otherwise your suggestion ./mystdout 2>&1 | tee output.txt should also work.

Upvotes: 3

grundic
grundic

Reputation: 4921

Solution from @Pierre should work. Otherwise I would suggest intercept stdout/stderr from external process and use logging with two handlers: one for console, another for specific file. Here is and example of log configuration.

Upvotes: 3

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