How to execute multiline python code from a bash script?

Question

I need to extend a shell script (bash). As I am much more familiar with python I want to do this by writing some lines of python code which depends on variables from the shell script. Adding an extra python file is not an option.

result=`python -c "import stuff; print('all $code in one very long line')"`

is not very readable.

I would prefer to specify my python code as a multiline string and then execute it.

score 25 · Accepted Answer · answered Oct 19 '16 at 23:38

25

Use a here-doc:

result=$(python <<EOF
import stuff
print('all $code in one very long line')
EOF
)

answered Oct 19 '16 at 23:38

Barmar

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If one does not need the return value, is it then possible to ommit the "$("? – Siete Jan 05 '23 at 09:55
1

Yes. That's just the normal use of a here-document. – Barmar Jan 05 '23 at 16:37

score 7 · Answer 2 · edited May 23 '17 at 12:23

7

Tanks to this SO answer I found the answer myself:

#!/bin/bash

# some bash code
END_VALUE=10

PYTHON_CODE=$(cat <<END
# python code starts here
import math

for i in range($END_VALUE):
    print(i, math.sqrt(i))

# python code ends here
END
)

# use the 
res="$(python3 -c "$PYTHON_CODE")"

# continue with bash code
echo "$res"

edited May 23 '17 at 12:23

Community

1
1

answered Oct 19 '16 at 23:42

cknoll

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How to return two variables to "res"? Thanks. – Lion Lai Apr 08 '20 at 08:48
1

res contains a string with the output. So you have to parse the string. Constructs like `a, b = "foo", "bar"` are imho not possible in bash. – cknoll Apr 10 '20 at 08:36
This is great because it doesn't tie up `stdin` – jez Aug 01 '20 at 15:21

How to execute multiline python code from a bash script?

2 Answers2

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