traceback in some cases when callling grep -c from subprocess.check_output

I got a very strange behaviour with subprocess.check_out:

I want to get the grep -c result:

In [50]: !grep -c 'def ' repos/clara.aaa_hotmail.com/*.py 0 In [52]: !grep -c 'def ' repos/saad.aaa_gmail.com/*.py 3 In [53]: 

with this one I get it well

In [53]: from subprocess import check_output In [54]: check_output([f"grep -c 'def ' repos/saad.aaa_gmail.com/*.py"], shell=True) Out[54]: b'3\n' 

with the other:

In [55]: check_output([f"grep -c 'def ' repos/clara.aaa_hotmail.com/*.py"], shell=True) --------------------------------------------------------------------------- CalledProcessError Traceback (most recent call last) <ipython-input-55-6c66bfb457a5> in <module> ----> 1 check_output([f"grep -c 'def ' repos/clara.aaa_hotmail.com/*.py"], shell=True) /usr/lib/python3.8/subprocess.py in check_output(timeout, *popenargs, **kwargs) 413 kwargs['input'] = empty 414 --> 415 return run(*popenargs, stdout=PIPE, timeout=timeout, check=True, 416 **kwargs).stdout 417 /usr/lib/python3.8/subprocess.py in run(input, capture_output, timeout, check, *popenargs, **kwargs) 514 retcode = process.poll() 515 if check and retcode: --> 516 raise CalledProcessError(retcode, process.args, 517 output=stdout, stderr=stderr) 518 return CompletedProcess(process.args, retcode, stdout, stderr) CalledProcessError: Command '["grep -c 'def ' repos/clara.aaa_hotmail.com/*.py"]' returned non-zero exit status 1. In [56]: 

Note: we are not dealing with pipe | Cf. python subprocess.check_output doesn't return when cat | grep combination