seek and write functions in Python doesn't want to work together.

[OpenGuard]

song = "mysound.mp3"
fh = open(song, "w")
fsize = os.path.getsize(song)
fh.seek(fsize-125)
fh.write("Test1")
fh.close()
Result: 0 byte file

Why it so and how can I write to a specific location ?

[Bachstelze]

Opening a file with mode="w" will overwrite it, so in your script, fsize will be 0. You want mode="a".

[unknownPoster]

Opening a file with mode="w" will overwrite it, so in your script, fsize will be 0. You want mode="a".

Just for further information I would look at the following link: http://diveintopython.org/file_handling/file_objects.html

Especially, section 6.2.4

[OpenGuard]

Opening a file with mode="w" will overwrite it, so in your script, fsize will be 0. You want mode="a".

a appends text, no matter where I am ( EOF + string, not string + edited + string + EOF ). Any other ways of achieving what I want ?

[Can+~]

Open it on "r+", so you can jump to the desired line and write there (assuming there's a file there in the first place).

And jump to seek(-125, os.SEEK_END)

[OpenGuard]

Open it on "r+", so you can jump to the desired line and write there (assuming there's a file there in the first place).

And jump to seek(-125, os.SEEK_END)

Bingo! Thank you :)