Not able to use print statement after using subprocess

Question

I'm using zbarcam to read barcodes, since zbarcam doesn't terminate automatically after reading a code.

Here's my parking-mng.py file:

#!/usr/bin/python import subprocess import MySQLdb as db from config import * import sys temp = '' def scanfun(): subprocess.call("./k.sh") reg = sys.stdin.readline().strip() con = None con = mdb.connect(server, user, pwd, database); cur = con.cursor() print "successful" while(1): print "------Parking Sector 11----------" print "Select : " print """1. Scan Code\n2. Update Balance\n3. Exit\n""" choice = raw_input() if choice == '1': scanfun() else: break

Here's my k.sh file:

#!/bin/bash tmp=/tmp/barcode.$$ zbarcam --raw /dev/video1 > $tmp & pid=$! # Sleep until file has content while [[ ! -s $tmp ]] ; do sleep 1 done kill $pid cat $tmp | ./parking-mng.py

The problem is that the print statement is not working, nothing is getting printed on the terminal.

your script is probably waiting on the readline() because there is no \n on stdin. — Chronial
– Chronial, Commented Apr 28, 2013 at 16:33
@Chronial No it's not because I'm able to update the database after the print statement, its probably printing somewhere else than terminal. I don't know why — Kartik Anand
– Kartik Anand, Commented Apr 28, 2013 at 16:34
@Chronial Also after scanfun() ends the while loop enters again and print "------Parking Sector 11----------" is being displayed, only what is inside the scanfun() is not being displayed. — Kartik Anand
– Kartik Anand, Commented Apr 28, 2013 at 16:38

shx2 · Accepted Answer · 2013-04-28 17:02:10Z

So your k.sh runs parking-mng.py, which then runs k.sh, which then runs parking-mng.py, which then runs k.sh, which then runs parking-mng.py, which then runs k.sh, which then runs parking-mng.py, which then runs k.sh, which then runs parking-mng.py, which then runs k.sh, which then runs parking-mng.py, which then runs k.sh, which then runs parking-mng.py, which then runs k.sh, which then runs parking-mng.py, which then runs k.sh, which then runs parking-mng.py, which then runs k.sh, which then runs parking-mng.py, which then runs k.sh, which then runs parking-mng.py, which then runs k.sh, which then runs parking-mng.py, which then runs k.sh, which then runs parking-mng.py, which then runs k.sh, which then runs parking-mng.py, which then runs k.sh, which then runs parking-mng.py, which then runs k.sh, which then runs parking-mng.py, which then runs k.sh, which then runs parking-mng.py, which then runs k.sh, which then runs parking-mng.py, ...

Infinite recursion much?

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