[Tutor] subprocess.getstatusoutput : UnicodeDecodeError

[Chris Warrick]

On 22 September 2017 at 03:57, Evuraan <evuraan at gmail.com> wrote:
>>>> result = subprocess.run(["tail", "-400", "/tmp/pmaster.txt"], stdout=subprocess.PIPE)
>>>> result.returncode
> 0
>>>> subprocess.getstatusoutput("file  /tmp/pmaster.txt",)
> (0, '/tmp/pmaster.txt: Non-ISO extended-ASCII text, with very long
> lines, with LF, NEL line terminators')
>>>>

You’re still using the deprecated function.

>>> subprocess.run(['file', '/tmp/pmaster.txt'], stdout=subprocess.PIPE)
CompletedProcess(args=['file', '/tmp/pmaster.txt'], returncode=0,
stdout=b'/tmp/pmaster.txt: Non-ISO…\n')
>>> result = _  # underscore means result of previous line in interactive mode
>>> result.stdout
b'/tmp/pmaster.txt: Non-ISO…line terminators\n'
>>> result.returncode
0

And if you want to get a Unicode string (if output of command is your
system encoding, hopefully UTF-8):

>>> subprocess.run(['file', '/tmp/pmaster.txt'], stdout=subprocess.PIPE, universal_newlines=True)
CompletedProcess(args=['file', '/tmp/pmaster.txt'], returncode=0,
stdout='/tmp/pmaster.txt: Non-ISO…\n')
>>> (_.stdout is an unicode string)

Also, going back to your original example: you should not be using
`tail` from within Python. You should not depend on tail being
available (it’s not on Windows), and there may also be version
differences. Instead of tail, you should use Python’s standard file
operations (open()) to accomplish your task.

[advertisement] Extra reading on security (shell=False) and the
necessity of calling subprocesses:
https://chriswarrick.com/blog/2017/09/02/spawning-subprocesses-smartly-and-securely/
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-- 
Chris Warrick <https://chriswarrick.com/>
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