Python Popen sending to process on stdin, receiving on stdout

Question

I pass an executable on the command-line to my python script. I do some calculations and then I\'d like to send the result of these calculations on STDIN to the executable. When

Answer 1

A working example

#!/usr/bin/env python
import subprocess
text = 'hello'
proc = subprocess.Popen(
    'md5sum',stdout=subprocess.PIPE,
    stdin=subprocess.PIPE)
proc.stdin.write(text)
proc.stdin.close()
result = proc.stdout.read()
print result
proc.wait()

to get the same thing as “execuable < params.file > output.file”, do this:

#!/usr/bin/env python
import subprocess
infile,outfile = 'params.file','output.file'
with open(outfile,'w') as ouf:
    with open(infile,'r') as inf:
        proc = subprocess.Popen(
            'md5sum',stdout=ouf,stdin=inf)
        proc.wait()