How to point ffmpeg concatenate cmd to a specific directory-variable

a simple question, I think :/
I have a directory containing some mp4 files which i want to concatenate with ffmpeg.

In this case the directory is stored in <folder_path> and can be recalled with

<print(‘folder_path=”, str(folder_path[0]))>

Now I want to concatenate all mp4 files within this folder <folder_path>with ffmpeg by first making the “file.txt’ list:

<for f in *.mp4; do echo “file ‘$f'” >> list_all_mp4_videos.txt; done>

Where and how do I point ffmpeg to the right directory?

tried this:
os.chdir(str(folder_path[0]))
for f in (*.mp4); do echo “file ‘$f'” >> list_all_mp4_videos.txt; done

And return is:
File “/home/testcase/source/RMS/Utils/BatchFFfileFramesOneMP4.py”, line 150
for f in (*.mp4); do echo “file ‘$f'” >> list_all_mp4_videos.txt; done
^
SyntaxError: invalid syntax