[Tutor] Running external commands from Python

[David Hutto]

On Fri, Jun 25, 2010 at 9:37 PM, Randy Kao <randykao at gmail.com> wrote:
> Thanks for the great and quick feedback from everyone!
> That definitely clears things up.
> -Randy
> On Fri, Jun 25, 2010 at 5:16 PM, Steven D'Aprano <steve at pearwood.info>
> wrote:
>>
>> On Sat, 26 Jun 2010 08:46:17 am Randy Kao wrote:
>> > Hi all,
>> >
>> > I'm a newbie to Python (switching from Perl) and had a question about
>> > the best way to run external commands in Python.
>> [...]
>> > through: os.popen, os.popen2, os.popen3, os.system,
>> > commands.getoutput()
>>
>>
>> os.system is the oldest way, and it's pretty much obsolete. Only use it
>> for quick-and-dirty scripts when you're too lazy to do the right thing
>> and don't care who knows it. It doesn't capture either stdin or stdout,
>> only the return value.
>>
>> os.popen, popen2 and popen3 are probably closer to what you're used to
>> in Perl. They basically differ in how many file handles they return:
>>
>> popen returns the external command's stdout as a file handle.
>> popen2 returns (stdin, stdout)
>> popen3 returns (stdin, stdout, stderr)
>>
>> The commands module is meant as an easier to use front end to the popen*
>> functions, for times where popen* are too much and system is too
>> little. If all you want is the output (stdout + stderr) of an external
>> command:
>>
>> import commands
>> output = commands.getoutput('ls -l foo*')
>>
>> will do the trick.
>>
>>
>> --
>> Steven D'Aprano
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And I was like...me too.