how to test a unix command in Python?

Question

How would I go about testing a unix command like bc? For example;

philippe$ bc
bc 1.06
Copyright 1991-1994, 1997, 1998, 2000 Free Software Foundation, Inc.
This is free software with ABSOLUTELY NO WARRANTY.
For details type `warranty'. 
2 + 2
4
3 * 10
30
10 / 5
2
-1
-1

I'm familiar with the modules subprocess and os in python. I also was reading about ScriptTest, but I don't know exactly how to use it ... What I need is to invoke the tool, then pass some operations like 2+2, get that result ... the remaining it's easy. I was wondering if there's a easier way to do it without too much parsing ...

stackoverflow.com/questions/10372012/…

Ranjith Ramachandra
– Ranjith Ramachandra

2013-10-21 05:15:31 +00:00
Commented Oct 21, 2013 at 5:15 — Ranjith Ramachandra
– Ranjith Ramachandra, Commented Oct 21, 2013 at 5:15
stackoverflow.com/questions/3679974/…

Ranjith Ramachandra
– Ranjith Ramachandra

2013-10-21 05:16:22 +00:00
Commented Oct 21, 2013 at 5:16 — Ranjith Ramachandra
– Ranjith Ramachandra, Commented Oct 21, 2013 at 5:16

steveha · Accepted Answer · 2013-10-21 05:15:16Z

2

I haven't tried it, but this is designed to solve your problem:

http://pexpect.sourceforge.net/pexpect.html

answered Oct 21, 2013 at 5:15

steveha

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ishikun · Accepted Answer · 2013-10-21 05:19:51Z

2

You might want to look into the sh module, it wraps over unix commands and allows you to call them as if they were functions. (You can also pass in what you want and retrieve the output)

answered Oct 21, 2013 at 5:19

ishikun

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2 Comments

ishikun Over a year ago

I haven't used sh with an interactive command but I'm guessing it can be used via interactive callbacks

ishikun Over a year ago

Also note: you can leverage the stdin and stdout to the command, in your case bc, with the special keywords _in and _out.

MangoHands · Accepted Answer · 2013-10-21 17:40:55Z

1

For running bc, the parsing is pretty easy. You can use subprocess.PIPE for communicating with the subprocess:

import subprocess as sp

cmd = 'bc'
p = sp.Popen(cmd, stdin = sp.PIPE, stdout = sp.PIPE)

# Pass in input, read output
p.stdin.write("2 + 2\n");
result = p.stdout.readline()
print 'Got result: %s'%result

p.stdin.close() # This sends EOF to bc, which closes it.
retval = p.wait()
print '%s finished with return value %i'%(cmd, retval)

answered Oct 21, 2013 at 17:40

MangoHands

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