How to capture stdout into a string?

[Michael Davis]

Peter Hansen wrote:

> Michael Davis wrote:
>> 
>> Hi,
>> 
>> I'm using libftp. The FTP.dir() function gets the remote directory
>> listing and prints it to standard out. How can I capture that in a
>> string?
>> 
>> If I were using an external process, I know I could open a pipe to it.
>> But it's not an external process.
>> 
>> I'm sure there's a tricky way of doing it by getting the file descriptor
>> for stdout and reading from it directly, but I was hoping to avoid going
>> that low-level. I will if I must though.
> 
> The best option by far (and really the easiest) to figure out
> stuff like this is to check the source.
> 
> In this case, you can see that dir() calls retrlines() with
> the LIST argument and no callback function.  As the notes
> say, this directs the output to stdout.
> 
> You must specify a callback function of some kind.  The best
> is probably a small class with a __call__ method, but this
> little baby seems to work too, although it may not be quite
> enough to work in the general case yet.  It grabs lines that
> are passed to it into a list, until it is called with an
> empty argument, at which point it returns the saved list
> and deletes it, ready for another bunch of lines:
> 
>>>> def grablines(line='', lines=[]):
> ...    if line:
> ...       lines.append(line)
> ...    else:
> ...       result = lines[:]
> ...       del lines[:]
> ...       return result
> ...
>>>> grablines()
> []
>>>> grablines('test')
>>>> grablines('test')
>>>> grablines('test')
>>>> grablines()
> ['test', 'test', 'test']
>>>> ftp.dir(grablines)
>>>> grablines()
> ['total 62', '-rw-r--r--  1 engcorp  netdial      0 Jan 11  2000
> [.addressbook',
> '-rw-------  1 engcorp  netdial   2285 Jan 11  2000 .addressbook.lu',
> '-rw------
> -  1 engcorp  netdial   6459 May 21 23:42 .bash_history', '-rw-r--r--  1
> engcorp
>   netdial     29 Jun 17  2001 .forward', '-rw-------  1 engcorp  netdial 
>   12221
> .............]
> 
> 
> -Peter

Thanks again, Peter. I would have accepted the answer RTFM too - I realized 
that I hadn't read the FTP.dir() documentation carefully enough!

You've saved me a lot of time today!

Michael

-- 
Michael Davis
Damaru
Custom Programming - Web Development - Database Design
http://www.damaru.com
416-540-1284