Multi-line commands with 'python -c'

[Peter Otten]

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']