On Mon, 31 Oct 2016 09:12:57 +0100, Peter Otten wrote:
> Wildman via Python-list wrote:
>
>> Python 2.7.9 on Linux
>>
>> Here is a bash command that I want to run from a python
>> program: sudo grep "^user\:" /etc/shadow
>>
>> If I enter the command directly into a terminal it works
>> perfectly. If I run it from a python program it returns an
>> empty string. Below is the code I am using. Suggestions
>> appreciated.
>>
>> cmdlist = ["sudo", "grep", '"^$USER\:"', "/etc/shadow"]
>> p = subprocess.Popen(cmdlist,
>> stdout=subprocess.PIPE,
>> stderr=subprocess.PIPE)
>> shadow, err = p.communicate()
>> print shadow
>
> What happens if you hardcode $USER? Compare:
>
>>>> subprocess.Popen(["sudo", "echo", "$USER"],
> stdout=subprocess.PIPE).communicate()
> ('$USER\n', None)
>
> That should explain the empty result. Possible fix:
>
>>>> subprocess.Popen(["sudo", "echo", os.environ["USER"]],
> stdout=subprocess.PIPE).communicate()
> ('user\n', None)
>
> While a shell should work, too,
>
>>>> subprocess.Popen("sudo echo $USER", stdout=subprocess.PIPE,
> shell=True).communicate()
> ('petto\n', None)
>
> I'd prefer the os.environ lookup.
I have code using that approach but I am trying to save myself
from having to parse the entire shadow file. Grep will do it
for me if I can get code right.
--
<Wildman> GNU/Linux user #557453
The cow died so I don't need your bull!
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