How to capture environment state after running a shell script.

[attn.steven.kuo at gmail.com]

On Mar 13, 5:57 am, "Gerard Flanagan" <grflana... at yahoo.co.uk> wrote:
> Hello,
>
> I have a third party shell script which updates multiple environment
> values, and I want to investigate (and ultimately capture to python)
> the environment state after the script has run. But running the script
> as a child process only sets values for that process, which are lost
> after execution.  So I thought I could simply tack on an 'env' command
> line to the script input lines as shown below. However, using
> subprocess.Popen gives the error shown (even though the docs say that
> any file object may be used for stdin), and using popen2 hangs
> indefinitely. I think I'm missing something basic, any advice? Or is
> there a better approach?
>

(snipped)

> ########## first method ##########
> p = Popen('/bin/sh', stdin=buf)
> print p.stdout.readlines()
>
> Traceback (most recent call last):
>   File "scratch.py", line 36, in ?
>     p = Popen('/bin/sh', stdin=buf)
>   File "/usr/local/lib/python2.4/subprocess.py", line 534, in __init__
>     (p2cread, p2cwrite,
>   File "/usr/local/lib/python2.4/subprocess.py", line 830, in
> _get_handles
>     p2cread = stdin.fileno()
> AttributeError: StringIO instance has no attribute 'fileno'
>
> ########## second method ##########
> cmdout, cmdin = popen2('/bin/sh')
> for line in buf:
>     cmdin.write(line)
>
> ret = cmdout.readlines()
> cmdout.close()
> cmdin.close()
>
> print ret



First close the input so that the (sub) process
knows to terminate and flush the output.  Then,
you can read from the output:

import subprocess
import popen2

p = subprocess.Popen(["/bin/sh"], stdin=subprocess.PIPE,
        stdout=subprocess.PIPE)

p.stdin.write("env -i FOO=BAR\n")
p.stdin.close()
status = p.wait()
ret = p.stdout.readlines()
p.stdout.close()

print ret

# Or

cmdout, cmdin = popen2.popen2("/bin/sh")
cmdin.write("env -i FOO=BAR\n")
cmdin.close()
ret = cmdout.readlines()
cmdout.close

print ret

--
Hope this helps,
Steven