How to redirect output of python script to bash variable?

Question

When redirecting the output of a python script, when echoing the output it seems to work, but when I actually use it with another object, it breaks and cuts off everything after it.

In this case, we have VERSION set to "nice dude"

VERSION=$(python3 -c "print('nice dude')")

And printing the variable alone seems to work

$ echo $VERSION

>>> nice dude

But when I implement this value with anything else, Python for example:

$ python3 -c "print('$VERSION')"

>>>   File "<string>", line 1
>>>     print('nice dude
>>>                     ^
>>> SyntaxError: EOL while scanning string literal

Or when I print it again with some concatenation:

$ echo $VERSION hehe

>>>  hehedude

I'm not sure what's happening but it seems to be some sort of carriage return when printing an output produced by python python3.9.1.

There is always a newline at the end of a print, unless you change it explicitly. Use print("...", end="") — Thierry Lathuille
– Thierry Lathuille, Commented Feb 8, 2021 at 9:38

AKX · Accepted Answer · 2021-02-08 09:36:16Z

1

After

VERSION=$(python3 -c "print('nice dude')")

the VERSION shell variable will contain a trailing newline, so interpolating it into Python code with python3 -c "print('$VERSION')" will result in

print('nice dude
')

which is not valid Python.

You can either add , end="") to the original print or figure out some other way to strip the trailing newline, or use e.g. triple quotes.

answered Feb 8, 2021 at 9:36

AKX

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2 Comments

Aven Desta Over a year ago

How were you able to replicate the result. Mine is ok. I didn't get any error

AKX Over a year ago

I'm currently on the bus, I didn't even try replicating this since I can just see the issue...

Aven Desta · Accepted Answer · 2021-02-08 09:50:02Z

0

I couln't replicate your result so I tried to look for what might have caused your error.

>> "This is a test

Then I got the same error.

It seems your error is that there is un-closed quote at the end.

Look here for more.

So you're probably forgetting closing an opened quote somewhere at the end. Here is what possibly might I happened

VERSION=$(python3 -c "print('nice dude')")

python3 -c "print('$VERSION)"
  File "<string>", line 1
    print('nice dude)
                    ^
SyntaxError: EOL while scanning string literal

edited Feb 8, 2021 at 9:50

answered Feb 8, 2021 at 9:44

Aven Desta

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1 Comment

Koyomi-Oniichan Over a year ago

I can see what you're referring to but I actually did include the other quote $ python3 -c "print('$VERSION')" It prints like that in the error message because of some strange reason, similar to a carriage return.

Rob Evans · Accepted Answer · 2021-06-11 08:04:32Z

0

I added and wrapped the python command with echo and it worked fine:

VERSION=$(echo $(python3 -c "print('nice dude')"))
$> echo $VERSION
nice dude

answered Jun 11, 2021 at 8:04

Rob Evans

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