Call shell script from python code without any return value (0) or new lines

Question

Let's say my shell script returns a value of '19' when it is run. I'd like to store that value (without any return value of 0 or empty lines) into a variable in my python code for use later.

There are many questions here with similar reference to mine but I have yet to find a solution where the shell script is returning me '19' without a extra return value of 0 or new lines.

Using subprocess.call('bash TestingCode', shell=True) in the python code returns me exactly what I want however when I store this command in a variable and then print the variable, it prints with an extra 0.

answer = subprocess.call('bash TestingCode', shell=True)
print answer

>>19
>>0

I then tried an example from this question: How to return a value from a shell script in a python script

However it returns me an extra empty line instead.

answer = subprocess.check_output('bash TestingCode', shell=True)
print answer
>>19
>> 

I really appreciate the help!

UPDATE: TestingCode script

#!/bin/bash
num=19
echo $num

Answer 1

Just call it like this:

import subprocess

answer = subprocess.check_output('bash TestingCode', shell=True)
answer = answer.rstrip()

The reason is that your shell script is printing 19 followed by a new line. The return value from subprocess.check_output() will therefore include the new line produced by the shell script. Calling str.rstrip() will remove any trailing whitespace, leaving just '19' in this case.

Answer 2

尝试调用subprocess.Popen ，它返回不带0的值。

Answer 3

This works for me. I suspect you have a problem in your shell script that is causing the output.

$ cat test.sh
#!/bin/sh
exit 19
(0) austin@Austins-Mac-8:~
$ python2.7
Python 2.7.10 (default, Aug 22 2015, 20:33:39)
[GCC 4.2.1 Compatible Apple LLVM 7.0.0 (clang-700.0.59.1)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import subprocess
>>> subprocess.call('bash test.sh', shell=True)
19
>>>