I've read everything there is on subprocess.Popen but I think I'm missing something.
I need to be able to execute a unix program which reads a data stream from a list created in the python script and write the result of that program to a file. From the bash prompt I do this all the time with no problem but now I am trying to to this from within a python script which preprocesses some binary files and a lot of data before coming to this stage.
Lets look at a simple example not including all the preprocessing:
import sys
from pylab import *
from subprocess import *
from shlex import split
# some arbitrary x,y points
points = [(11,31),(13,33),(15,37),(16,35),(17,38),(18,39.55)]
commandline = 'my_unix_prog option1 option2 .... > outfile'
command = split(commandline)
process = Popen(command, stdin=PIPE, stdout=PIPE, stderr=PIPE)
print process.communicate(str(points))
The way this would be executed in bash is:
echo "11 31
13 33
15 37
16 35
17 38
18 39.55" | my_unix_prog option1 option2 .... > outfile
The way the data is fed into the unix prog is important as well, I should be formatted in 2 columns separated by whitespace.
Any help is appreciated...
SOLVED!
With the help of Dhara and xhainingx I was able to figure this out:
import sys
from pylab import *
from subprocess import *
from shlex import split
# some arbitrary x,y points
points = [(11,31),(13,33),(15,37),(16,35),(17,38),(18,39.55)]
commandline = 'my_unix_prog option1 option2 ....'
command = split(commandline)
process = Popen(command, stdin=PIPE, stdout=open('outfile', 'w'), stderr=PIPE)
for p in points:
process.stdin.write(str(p[0]) + ' ' + str(p[1]) + '\n')
print process.communicate()
This works very well, thanks.