Use pdb.set_trace() in a script that reads stdin via a pipe
<p>I have a python script that reads stdin via a pipe, and I cannot seem to use it with pdb.set_trace().  </p>

<p>my_script.py:</p>

<pre><code>#!/usr/bin/env python
import sys
import pdb

def main():
    for line in sys.stdin:
        print "Printing a line: " +line

if __name__=='__main__':
    status = main()
</code></pre>

<p>Suppose tempfile.csv is some file with two lines,</p>

<pre><code>$ cat tempfile.csv 
line1
line2
</code></pre>

<p>then I can run my script with:
$ cat tempfile.csv | ./my_script.py, and everything is fine:</p>

<pre><code>$ cat tempfile.csv | ./my_script.py 
Printing a line:  line1

Printing a line:  line2
</code></pre>

<p>On the other hand, if I put pdb.set_trace() anywhere then I get an error.  For example, putting pdb.set_trace() below def main(), then I get </p>

<pre><code>$ cat tempfile.csv | ./my_script.py 
&gt; /home/ilangmore/mobiuss/TM/branches/hadooprotype/my_script.py(7)main()
-&gt; for line in sys.stdin:
(Pdb) *** NameError: name 'line1' is not defined
(Pdb) *** NameError: name 'line2' is not defined
(Pdb) 
Traceback (most recent call last):
  File "./my_script.py", line 11, in &lt;module&gt;
    status = main()
  File "./my_script.py", line 7, in main
    for line in sys.stdin:
  File "./my_script.py", line 7, in main
    for line in sys.stdin:
  File "/usr/lib/python2.7/bdb.py", line 48, in trace_dispatch
    return self.dispatch_line(frame)
  File "/usr/lib/python2.7/bdb.py", line 67, in dispatch_line
    if self.quitting: raise BdbQuit
bdb.BdbQuit
</code></pre>

<p>Note that my question is probably related to <a href="http://stackoverflow.com/questions/3101777/run-pdb-without-stdin-stdout-using-fifo">this question</a> (i.e. pdb by default reads from stdin), but I need more help.</p>
