Documentation for io.IOBase class and it's seek() method at https://docs.python.org/3/library/io.html mentions SEEK_* constants like:

"    SEEK_SET or 0 – start of the stream (the default); offset should be zero or positive
    SEEK_CUR or 1 – current stream position; offset may be negative
    SEEK_END or 2 – end of the stream; offset is usually negative
"

It seems, they actually should be used as os.SEEK_SET, os.SEEK_CUR and os.SEEK_END.

As indicated in the seek docs ( https://docs.python.org/3/library/io.html#io.IOBase.seek ), all three names were added to the io module in 3.1:

> New in version 3.1: The SEEK_* constants.

Since they're part of the io module too, there is no need to qualify them on the io module docs page.

They're available in os as well, but you don't need to import it to use them. The OS specific addition position flags are explicitly documented to be found on the os module.

Seems in my, quite old 3.4.5 version, it doesn't work:

$ python3
Python 3.4.5 (default, Jun  1 2017, 13:52:39) 
[GCC 4.4.7 20120313 (Red Hat 4.4.7-18)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> f = open('/tmp/text.txt', 'r')
>>> f.seek(0, SEEK_END)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'SEEK_END' is not defined
>>> f.close()
>>> 
>>> import os
>>> f = open('/tmp/text.txt', 'r')
>>> f.seek(0, os.SEEK_END)
214
>>> f.close()

OK, I got it. Sorry for disturbing you.

The should be called like: io.SEEK_*