best way of testing a program exists before using it?
hpsekhon at googlemail.com
Mon Sep 11 17:55:04 CEST 2006
Rob Wolfe wrote:
> Hari Sekhon wrote:
>> I am writing a wrapper to a binary command to run it and then do
>> something with the xml output from it.
>> What is the best way of making sure that the command is installed on the
>> system before I try to execute it, like the python equivalent of the
>> unix command "which"?
>> Otherwise I'd have to do something like:
>> if os.system('which somecommand') != 0:
>> print "you don't have %s installed" % somecommand
>> I know that isn't portable which is why a python solution would be
>> better (although this will run on unix anyway, but it'd be nice if it
>> ran on windows too).
> IMHO this is pretty portable:
>>>> def is_on_path(fname):
> ... for p in os.environ['PATH'].split(os.pathsep):
> ... if os.path.isfile(os.path.join(p, fname)):
> ... return True
> ... return False
That works well and is portable, fits nicely. I was actually curious if
somebody already came across this and perhaps put a func like this in
the standard modules...
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