Simplest form that worked for me.

import traceback

try:
    print(4/0)
except ZeroDivisionError:
    print(traceback.format_exc())

Output

Traceback (most recent call last):
  File "/path/to/file.py", line 51, in <module>
    print(4/0)
ZeroDivisionError: division by zero

Process finished with exit code 0

I believe the several answers here recommending you manage your try/except blocks more tightly are the answer you're looking for. That's a style thing, not a library thing.

However, at times we find ourselves in a situation where it's not a style thing, and you really do need the line number to do some other programattic action. If that's what you're asking, you should consider the traceback module. You can extract all the information you need about the most recent exception. The tb_lineno function will return the line number causing the exception.

>>> import traceback
>>> dir(traceback)
['__all__', '__builtins__', '__doc__', '__file__', '__name__', '__package__', '_format_final_exc_line', '_print', '_some_str', 'extract_stack', 'extract_tb', 'format_exc', 'format_exception', 'format_exception_only', 'format_list', 'format_stack', 'format_tb', 'linecache', 'print_exc', 'print_exception', 'print_last', 'print_list', 'print_stack', 'print_tb', 'sys', 'tb_lineno', 'types']
>>> help(traceback.tb_lineno)
Help on function tb_lineno in module traceback:

tb_lineno(tb)
Calculate correct line number of traceback given in tb.
Obsolete in 2.3

Newer versions of the traceback plumbing fix the issue prior to 2.3, allowing the code below to work as it was intended: (this is the "right way")

import traceback
import sys

try:
    raise Exception("foo")
except:
    for frame in traceback.extract_tb(sys.exc_info()[2]):
        fname,lineno,fn,text = frame
        print "Error in %s on line %d" % (fname, lineno)

Tested on Python 3.6

class FlowException(Exception):
    pass

def something():
    raise ValueError

try:
   something()
except Exception as e:
    raise FlowException("Process Exception", e)

Output has line numbers:

Traceback (most recent call last):
  File "/Users/diman/PycharmProjects/invites/test.py", line 8, in <module>
    something()
  File "/Users/diman/PycharmProjects/invites/test.py", line 5, in something
    raise ValueError
ValueError

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Users/diman/PycharmProjects/invites/test.py", line 10, in <module>
    raise FlowException("Process Exception", e)
__main__.FlowException: ('Process Exception', ValueError())

For Python 2 try using internal logger ".exception()" method instead of using monstrous "sys" module.

import logging
logger = logging.getLogger()

try:
    something()
except Exception as e:
    logger.exception(e)
    raise FlowException("Process Exception", e)

If you can't for any reason use logging, There's the standard package traceback, and you can do something like:

traceback.print_exc(file=sys.stdout)