How Can I Redirect Python\'s `print` Output to a File?

Redirect 'print' Output to a File

When attempting to redirect the 'print' output to a text file in Python, users may encounter challenges if their code doesn't behave as expected. In such cases, employing sys.stdout to redirect the output can lead to unexpected results.

A straightforward and recommended approach is to print directly to a file object:

with open('out.txt', 'w') as f:
    print('Filename:', filename, file=f)  # Python 3.x
    # print >> f, 'Filename:', filename   # Python 2.x

Alternatively, for a one-off script, redirecting 'sys.stdout' can be suitable:

import sys

orig_stdout = sys.stdout
f = open('out.txt', 'w')
sys.stdout = f

for i in range(2):
    print('i = ', i)

sys.stdout = orig_stdout
f.close()

Since Python 3.4, the standard library provides a context manager that simplifies this task:

from contextlib import redirect_stdout

with open('out.txt', 'w') as f:
    with redirect_stdout(f):
        print('data')

External redirection from the shell can also be an effective option:

./script.py > out.txt

To troubleshoot potential issues, consider checking the first filename in the script, which may not be initialized. Additionally, verifying that the folder exists and printing out 'bamfiles' can help identify any problems with file discovery. Utilizing 'os.path.join' and 'os.path.basename' for path and filename manipulation is recommended for optimal code clarity.

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