how to get the config file path of redis through a ps command

Question

when i typed the ps -ef | grep redis and tried to find the config file path which redis process is currently using. But get a result like:

root ... pid ... ./redis-server 0.0.0.0:6379

it didn't show the full startup arguments. the expect result should be something like:

root ... pid ... ./redis-server /etc/redis/redis.conf

so, is there any way i can find the /path/to/config but not using redis-cli info?

btw, cat /proc/{$pid}/cmdline shows the same result as ps command. OS: centos