[Tutor] sys.exit() not working

Michael P. Reilly arcege@speakeasy.net
Sat, 4 Aug 2001 16:45:50 -0400

On Sat, Aug 04, 2001 at 04:30:02PM -0400, fleet@teachout.org wrote:
> The only difference I see is that in the second test I provide an error
> condition and in the first test I don't.  Which brings me to another
> question:  The error returned if there are no jpg/JPG files in the
> directory appears to be a shell error message (RH Linux 7.0) and not a
> Python error (because of popen, I presume).  If I *need* an error
> condition after except, what do I put there (first test)?

Did you try the first expression in an interpreter?  I did and I got
no error (though there was a message written to stderr).  In fact,
popen won't return an error, even if you gave it an invalid command.

>>> string.split(os.popen('ls -1D /etc/*.[Jj][Pp][Gg]').read(), "\012")
ls: /etc/*.[Jj][Pp][Gg]: No such file or directory

The result is a list containing an empty string.  No exception is raised
so the except clause is not executed.  If you wanted an exception,
then you would have to check the result and raise an exception yourself.

Incidently, you might want to look at the glob module, it will do
this better for you, I think.  Also, readlines() doesthe same as
string.split(read(), '\n').

>>> os.popen('ls -1D /etc/*.[Jj][Pp][Gg]').readlines()
ls: /etc/*.[Jj][Pp][Gg]: No such file or directory
>>> import glob
>>> glob.glob('/etc/*.[Jj][Pp][Gg]')

(I use "/etc/" since I know there are no jpeg files there. ;))


| Michael P. Reilly                | arcege@speakeasy.net              |