calling subprocess

[Dave Angel]

On 02/22/2015 08:13 PM, jkuplinsky at gmail.com wrote:
>
> OK (1) sorry about for/from

That's not what you should be sorry about.  You should be sorry you 
didn't use cut&paste.

> (2) print() sounds nice, but fact is , no matter what I try, i always get C:\\apps instead of c:\apps. So in this sense print() doesn't help much. Obviously i'm doing something wrong -- which is what you perhaps call shotgun debugging; but that's why i'm asking.
>

You probably are getting confused about the difference between str() and 
repr().  If you print the repr() of a string, it'll add quotes around 
it, and escape the unprintable codes.  So it'll double the backslash. 
It also turns a newline into  \n, and tabs into \t, and so on.  Very useful.

That's also what happens when you print a list that contains strings. 
The individual elements of the list are converted using repr().  Watch 
for the quotes to get a strong hint about what you're seeing.

If you don't get a positive handle on how string literals relate to 
string variables, and on str() and repr(), and print(), you'll be 
jumping around the problem instead of solving it.



Back to your original problem, which had you trying to use 
subprocess.call to change the current directory.  Current directory is 
effectively (or actually) depending on the OS involved) an environment 
variable, and changes made in a child process are not magically returned 
to the parent.

But even though there is an os.chdir() in Python, you really shouldn't 
use it.  Long experience of many people show that you're better off 
manipulating the directories you need explicitly, converting any 
directory that's relative to something other than the current one, to an 
absolute.

-- 
DaveA