passing an argument to a python function from bash

Question

I am trying below commands

 python -c 'import sample; sample.Functionname()'
 python -c 'import sample; sample.printFxn("helloWorld")'

Both of these work well but when I pass a variable as an argument, I get the following error.

 File "<string>", line 1 import sample; sample.printFxn($filename) SyntaxError: invalid syntax

What is the proper way to pass a variable as an argument to a python function from bash?

write code in file in run it from file using sys.argv to get parameters. — furas
– furas, Commented Dec 22, 2017 at 10:19
You haven't provided the command line that causes the error. — jpmc26
– jpmc26, Commented Dec 22, 2017 at 10:53

chepner · Accepted Answer · 2017-12-22 14:28:51Z

7

Don't interpolate string variables into the command; pass the value as an argument to the Python script.

python -c 'import sys, sample; sample.printFxn(sys.argv[1])' "$fileName"

answered Dec 22, 2017 at 14:28

chepner

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Mureinik · Accepted Answer · 2017-12-22 10:18:39Z

0

Single quotes (') prevent the shell from parsing a string an evaluating variables. You can use double quotes instead so the shell will evaluate your variable:

python -c "import sample; sample.printFxn('$fileName')"

answered Dec 22, 2017 at 10:18

Mureinik

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2 Comments

jpmc26 Over a year ago

@SivakamiSubbu Be aware that including the input this way is technically a security vulnerability. If you know for a fact that none of your files names can have been crafted into malicious Python code, it's okay to run it manually. But if this is programmatic and going to be used with input from untrusted sources, I'd look at actually using the command line arguments system.

chepner Over a year ago

Consider if the value of fileName itself contains a single quote.

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