pipe.py

from subprocess import Popen, PIPE

# This is the exact same as running: ls -al | sort
p1 = Popen(["ls", "-al"], stdout=PIPE)
p2 = Popen(["sort"], stdin=p1.stdout, stdout=PIPE)
output = p2.communicate()[0]

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from subprocess import Popen, PIPE
cmd = 'blah'
p = Popen(cmd, stdout=PIPE, stderr=PIPE)
stdout, stderr = p.communicate()


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import sys
sys.stdout = open('file', 'w')
print 'test'


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# On Windows with shell=True, the COMSPEC environment variable specifies the default shell.
# The only time you need to specify shell=True on Windows is
# when the command you wish to execute is built into the shell (e.g. dir or copy).
# You do not need shell=True to run a batch file or console-based executable.

# the below command is same as the command,
#   dir wrong_file_name 2> err_file.log
from subprocess import call
cmd = 'dir wrong_file_name'
call(cmd, shell=True, stderr=open('err_file.log', 'w'))