In this example, I'm using Python 3.6.5 installed using pyenv in an OSX shell.
I've been toying around with some proof of concept file watching code and I figured using a delta of a file's current and last measured st_mtime would be enough to "detect" that a file has changed.
The code:
import os
def main():
file_path = 'myfile.txt'
last_modified = os.stat(file_path).st_mtime
while True:
check_last_modified = os.stat(file_path).st_mtime
delta = check_last_modified - last_modified
if delta != 0.0:
print("File was modified.")
last_modified = check_last_modified
if __name__ == '__main__':
main()
The weird thing is different types of basic file modification operations will result in "File was modified." printing more than once.
Assuming myfile.txt exists, I get a different number of prints based on the operation:
It prints 1 time with: $ touch myfile.txt
It prints 2 times with: $ echo "" > myfile.txt.
It prints 1 time with:
$ cat <<EOF > myfile.txt
> EOF
It prints 2 times with (empty line):
$ cat <<EOF > myfile.txt
>
> EOF
It prints 1 time using python to write an empty string:
def main():
with open('myfile.txt', 'w') as _file:
_file.write('')
if __name__ == '__main__':
main()
It prints 2 times using python to write a non-empty string:
def main():
with open('myfile.txt', 'w') as _file:
_file.write('a')
if __name__ == '__main__':
main()
The biggest difference seems to be the presence of a string other than a newline, but seeing as how the echo command results in two prints I'm not inclined to believe it's bound to that in any way.
Any ideas?
