Nobody <nob...@nowhere.com> writes: > On Wed, 29 Jul 2009 09:29:55 -0400, J Kenneth King wrote: > >> I wrote a script to process some files using another program. One thing >> I noticed was that both os.listdir() and os.path.walk() will return >> unescaped file names (ie: "My File With Spaces & Stuff" instead of "My\ >> File\ With\ Spaces\ \&\ Stuff"). I haven't had much success finding a >> module or recipe that escapes file names and was wondering if anyone >> could point me in the right direction. >> >> As an aside, the script is using subprocess.call() with the "shell=True" >> parameter. There isn't really a reason for doing it this way (was just >> the fastest way to write it and get a prototype working). I was >> wondering if Popen objects were sensitive to unescaped names like the >> shell. I intend to refactor the function to use Popen objects at some >> point and thought perhaps escaping file names may not be entirely >> necessary. > > Note that subprocess.call() is nothing more than: > > def call(*popenargs, **kwargs): > return Popen(*popenargs, **kwargs).wait() > > plus a docstring. It accepts exactly the same arguments as Popen(), with > the same semantics. > > If you want to run a command given a program and arguments, you > should pass the command and arguments as a list, rather than trying to > construct a string. > > On Windows the value of shell= is unrelated to whether the command is > a list or a string; a list is always converted to string using the > list2cmdline() function. Using shell=True simply prepends "cmd.exe /c " to > the string (this allows you to omit the .exe/.bat/etc extension for > extensions which are in %PATHEXT%). > > On Unix, a string is first converted to a single-element list, so if you > use a string with shell=False, it will be treated as the name of an > executable to be run without arguments, even if contains spaces, shell > metacharacters etc. > > The most portable approach seems to be to always pass the command as a > list, and to set shell=True on Windows and shell=False on Unix. > > The only reason to pass a command as a string is if you're getting a > string from the user and you want it to be interpreted using the > platform's standard shell (i.e. cmd.exe or /bin/sh). If you want it to be > interpreted the same way regardless of platform, parse it into a > list using shlex.split().
I understand; I think I was headed towards subprocess.Popen() either way. It seems to handle the problem I posted about. And I got to learn a little something on the way. Thanks! Only now there's a new problem in that the output of the program is different if I run it from Popen than if I run it from the command line. The program in question is 'pdftotext'. More investigation to ensue. Thanks again for the helpful post. -- http://mail.python.org/mailman/listinfo/python-list
