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Multi-line commands with 'python -c'


Peter Otten <__peter__ at web.de> wrote:

> Duncan Booth wrote:
> 
>> Chris Angelico <rosuav at gmail.com> wrote:
>> 
>>> On Sat, May 31, 2014 at 7:42 AM, Devin Jeanpierre
>>><jeanpierreda at gmail.com> wrote:
>>>> In unix shells you can literally use a new line. Or is that only
>> bash?
>>> 
>>> You can in bash, I know, but it's fiddly to type it; and more
>>> importantly, it's not a good point in the "this is cleaner than a
>>> series of pipes" argument. My primary recommendation, of course, was
>>> a three-line script saved as an actual file, but for a more direct
>>> parallel to the pipe-it-three-ways model, I wanted to use -c.
>> 
>> and you also wrote originally that it's fiddly to edit. I think that
>> Windows Powershell has (at least in the current ISE command line) got
>> the editing a bit better. It's a minor difference though and it has
>> taken Microsoft about 30 years to get to that point.
>> 
>> What may be a larger difference, or may just be my lack of Linux-foo,
>> is this:
>> 
>> PS C:\python33> $script = @"
>> import os
>> for root, dirs, files in os.walk("."):
>>     if len(dirs + files) == 1: print(root)
>> "@
>> 
>> PS C:\python33> python -c $script
>> .\Doc
>> .\Lib\concurrent\__pycache__
>> .\Lib\curses\__pycache__
>> ...
>> 
>> which is a style I've found useful for example when running a group
>> of related timeit.py commands as I can put things like multi-line
>> setup statements in a variable and then have a simpler command to
>> repeat. 
>> 
>> But bash as far as I can won't let me do that:
>> 
>> $ script='import os
>> for root, dirs, files in os.walk("."):
>>     if len(dirs + files) == 1: print(root)
>> '
>> $ python -c $script
>>   File "<string>", line 1
>>     import
>>          ^
>> SyntaxError: invalid syntax
>  
> $ script='import os
>> for root, dirs, files in os.walk("."):
>>     if len(dirs + files) == 1:
>>         print(root)
>> '
> $ python3 -c "$script"
> .
> ./heureka
> 
> $ python3 -c 'import sys; print(sys.argv)' $script
> ['-c', 'import', 'os', 'for', 'root,', 'dirs,', 'files', 'in', 
> 'os.walk("."):', 'if', 'len(dirs', '+', 'files)', '==', '1:',
> 'print(root)'] $ python3 -c 'import sys; print(sys.argv)' "$script"
> ['-c', 'import os\nfor root, dirs, files in os.walk("."):\n    if
> len(dirs + files) == 1:\n        print(root)\n']
> 
Thanks, I thought there must be a way to do that (and I should have 
remembered it). It nicely shows up the difference between the *nix 
shells that are all about processing the command line as a string and 
the Powershell way where it is all about objects (so a single value 
stays as a single argument).

-- 
Duncan Booth