[Tutor] Error Handling in python

[Steven D'Aprano]

On Thu, Jul 24, 2014 at 05:05:24PM +0530, jitendra gupta wrote:
> Hi All
> 
> My shell script is not throwing any error when I am having  some error in
> Python code.

This is a question about the shell, not about Python. I'm not an expert 
on shell scripting, but I'll try to give an answer.


> ~~~~~ shellTest.sh ~~~~~~~
> python test.py
> python second.py


One fix is to check the return code of the first python process:

[steve at ando ~]$ python -c pass
[steve at ando ~]$ echo $?
0
[steve at ando ~]$ python -c "raise Exception"
Traceback (most recent call last):
  File "<string>", line 1, in <module>
Exception
[steve at ando ~]$ echo $?
1


Remember that to the shell, 0 means "no error" and anything else is an 
error. So your shell script could look like this:

python test.py
if [ "$?" -eq 0 ]
then
  python second.py
fi



Another way (probably better) is to tell the shell to automatically exit 
if any command fails:


set -e
python test.py
python second.py



Hope this helps,


-- 
Steven