How to redirect docker container logs to a single file?

How about this option:

docker logs containername >& logs/myFile.log

It will not redirect logs which was asked for in the question, but copy them once to a specific file.

No need to redirect logs.

Docker by default store logs to one log file. To check log file path run command:

docker inspect --format='{{.LogPath}}' containername

/var/lib/docker/containers/f844a7b45ca5a9589ffaa1a5bd8dea0f4e79f0e2ff639c1d010d96afb4b53334/f844a7b45ca5a9589ffaa1a5bd8dea0f4e79f0e2ff639c1d010d96afb4b53334-json.log

Open that log file and analyse.

if you redirect logs then you will only get logs before redirection. you will not be able to see live logs.

EDIT:

To see live logs you can run below command

tail -f `docker inspect --format='{{.LogPath}}' containername`

Note:

This log file /var/lib/docker/containers/f844a7b45ca5a9589ffaa1a5bd8dea0f4e79f0e2ff639c1d010d96afb4b53334/f844a7b45ca5a9589ffaa1a5bd8dea0f4e79f0e2ff639c1d010d96afb4b53334-json.log will be created only if docker generating logs if there is no logs then this file will not be there. it is similar like sometime if we run command docker logs containername and it returns nothing. In that scenario this file will not be available.