What is printing this number after my python script executes

Question

Please forgive me for asking a simple question of python. This is my first time using python.

I'm writing this script on a mac book pro for now. It will probably be deployed on a Centos server later. The script grabs gets file as an argument. I'll deal with processing the output later.

#!/usr/bin/python
import sys
import subprocess

if len(sys.argv) < 2:
   print ("Not enough arguments")
   print ("Usage: " + sys.argv[0] + " log_file output_file")
   print ("i.e. " + sys.argv[0] + " stream.log output.csv")
   sys.exit(1)
else:
   input = open (sys.argv[1])
   output = open (sys.argv[2],'w')

proc = subprocess.Popen("cat " + input.name + " | cut -d ',' -f 3 | sort | uniq | wc -l", shell=True)

print "got here"
output.close()
print "got here22222"
input.close()

I just ran it from a terminal and it executes. However, after it prints out the last

got here22222

there's a delay of a couple seconds and then it prints out 567. However, there's no print 567 in my script above. Does anyone know why it's printing this number? How do I stop it from printing this number? Thanks in advance for any help you can give me.

./test.py a b
got here
got here22222
~/test$      567

Answer 1

The final stage of your pipeline is wc -l which is probably generating the number 567. It takes a few seconds to reach that point.

Answer 2

to stop this from happening you can wait for the subprocess using proc.wait() otherwise I guess the output of the piped commands is 567