Thursday, September 15, 2022

[FIXED] How to print to stderr in Python?

Issue

There are several ways to write to stderr:

print >> sys.stderr, "spam"  # Python 2 only.

sys.stderr.write("spam\n")

os.write(2, b"spam\n")

from __future__ import print_function
print("spam", file=sys.stderr)

What are the differences between these methods? Which method should be preferred?


Solution

I found this to be the only one short, flexible, portable and readable:

# This line only if you still care about Python2
from __future__ import print_function

import sys

def eprint(*args, **kwargs):
    print(*args, file=sys.stderr, **kwargs)

The optional function eprint saves some repetition. It can be used in the same way as the standard print function:

>>> print("Test")
Test
>>> eprint("Test")
Test
>>> eprint("foo", "bar", "baz", sep="---")
foo---bar---baz


Answered By - MarcH
Answer Checked By - Timothy Miller (PHPFixing Admin)

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