Pass variable to python function from bash script

Question

I am really struggling trying to figure out to pass variables from a bash script to a python function I have made. I have looked over numberous posts about the same issue and cant seem to understand what I am missing.

I have a python function script named fname_function.py:

from glob import glob
import os
import sys
first_arg=sys.argv[1]
second_arg=sys.argv[2]
third_arg=sys.argv[3]
def gFpath(reach,drive,date):
 list1 = glob(os.path.normpath(os.path.join(drive, reach, date,'*')))
 list2 =[]
 for afolder in list1:
 list2.append(glob(os.path.normpath(os.path.join(drive, reach, date, afolder, 'x_y_class?.asc'))))
 return list2
if __name__=='__main__':
 gFpath(first_arg,second_arg,third_arg)

And my bash script looks like:

reach="R4a"
drive= "D:\\"
dte="2015_04"
fnames=$(python fname_function.py "$reach" "$drive" "$dte")
for fname in $fnames; do echo "Script returned $fname"; done

The variables are being passed to the python script, but I cant seem to get list2 back to my shell script.

Thanks,

Dubbbdan

Answer 1

You can just run the Python file directly, like python fname_function.py "$reach" "$drive" "$dte"

However, sys.argv[0] will be fname_function.py in this case, so you'll want to set first_arg to sys.argv[1] and increment the other numbers as well.

Also, you don't output anything in your Python script. You should make the end of your script read:

if __name__=='__main__':
 fnames = gFpath(first_arg,second_arg,third_arg)
 for fname in fnames:
 print(fname)

which will print out 1 result from gFpath on each line.

• dubbbdan: gFpath was designed to return a list of file paths to the bash script. How would I access list2 from the shell script?
• iobender: You can assign the output to a variable in bash like so: fnames=$(python fname_function.py "$reach" "$drive" "$dte"). You can then loop over them with for fname in $fnames; do echo "Script returned $fname"; done. This might screw up if there are spaces in the filenames but I can't test on bash right now.
• dubbbdan: Thanks so much for you help! How ever when i implement the fname=... suggestion I am getting gfnames.sh: line 4: D:\: is a directory I was intentionally making it a directory i could change when I am working on different drives. Any ideas on how to pass a variable that resembles a directory?