easyproc 0.1.1

thin abstraction on subprocess.run to simplify admin scripts

easyproc is a very thin wrapper on the new suprocess.run() function in Python 3.5, just to simplify administrative scripting a bit. It addresses what I perceive to be three shortcomings in the Popen API (in order of egregiousness)

1. Input and output streams default to bytes. This is manifestly ridiculous in Python 3. easyproc turns on universal_newlines everywhere, so you don’t have to worry about decoding bytes.

2. Piping a chain of processes together is not particularly intuitive and takes a lot of extra work when not using shell=True. easyproc.pipe() provides a simple way to pipe a chain of shell commands into each other without the safety risk of granting a shell. Admittedly, if one is piping together a lot of shell commands, one might wonder why bother with python at all? Or better, why not use native python filters? Certainly, that is the preferable option in situations were “shelling out” creates a performance bottle-neck, but there are times where the performance cost is small, and, in terms of development speed, shell utilities are often ideally suited to parsing the output of shell commands. Easy things should be easy, right?

3. While not particularly egregious, and sometimes even useful, it can be annoying to split each command argument into a separate list item. easyproc commands can be strings or lists. If it’s a string, it’s run through shlex.split() prior to being passed to subprocess.run().

easyproc does not replace all the functionality of the subprocess module by a long shot, but it does try to expose much of it by passing additional kwargs to subprocess.run(), so many advanced use-cases should be possible, and one need only refer to the documentation for the subprocess module.

easyproc provides four simple functions for messing with shell commands. easyproc.run() simply runs the command you give it through shlex.split() if it is a string, and then sends it to suprocess.run() with universal_newlines turned on, and all additional kwargs passed along as well. easyproc.Popen() does the same, but it returns a Popen instance, in case you need to interact with a running process.

easyproc.grab() is like easyproc.run(), but it captures the stdout of the command. By default, it also splits the output into a list of lines, since many commands return output that is intended to be processed line by line. Turn off this behavior with split=False. Note that unlike subprocess.check_output(), this does not catch errors without adding check=True! easyproc.pipe() takes any number of commands as args and pipes them into each other in the order they are given. The output is captured and split, as with easyproc.grab(), unless otherwise specified.

easyproc also provides the three special variables from the subprocess module, PIPE, STDOUT, and DEVNULL, for those who know and care what they do.