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External Command - subprocess with advanced output processing

Project description

extcmd - subprocess with advanced output processing

This rather elaborate example shows a few interesting features of the library. Each line of the called command is passed to a Chain delegate, there are three copies made, the two first are just passed to another delegate while the last is modified with a Transform delegate. Finally all copies end up in our sink which is a composition of a simple Transform that prepends the stream name and a Redirect that, by default, just writes each line back to the corresponding stream.

Everything is encapsulated in a single module, extcmd >>> import extcmd >>> import re

Create our sink object, it will simply write stuff back to the right stream while prepending the stream name to each line for easy inspection (and fun) >>> sink = extcmd.Transform(lambda stream_name, line: “{0}: {1}”.format(stream_name, line), … extcmd.Redirect()) >>> better_subprocess = extcmd.ExternalCommandWithDelegate( … extcmd.Chain([ … sink, # pass one copy directly to the sink … sink, # pass second copy directly to the sink … # transform a third copy with regular expression … extcmd.Transform(lambda stream_name, line: re.sub(“hello”, “bye”, line, flags=re.I), sink), … ]) … )

After constructing that chain we can just call commands. As in subprocess there is also check_call() which raises an exception on failure. >>> returncode =[‘echo’, ‘Hello World’]) stdout: Hello World stdout: Hello World stdout: bye World

You can still look at returncode, it is returned from each call() >>> returncode 0

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Filename, size & hash SHA256 hash help File type Python version Upload date
extcmd-0.1.dev1.tar.gz (4.1 kB) Copy SHA256 hash SHA256 Source None Aug 29, 2011

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