Redis logfile permission error, but the permission is already 777

gentoo /var/log/redis # ls -al total 8 drwxrwxr-x 2 root redis 4096 12月 3 16:05 . drw-rw-r-- 5 root root 4096 12月 3 15:57 .. -rwxrwxrwx 1 redis redis 0 12月 3 16:05 redis.log gentoo /var/log/redis # sudo -u redis redis-server /etc/redis.conf *** FATAL CONFIG FILE ERROR *** Reading the configuration file, at line 175 >>> 'logfile /var/log/redis/redis.log' Can't open the log file: Permission denied I can run redis-server with root user, but I need run it with redis user. And then it print this error log. OS & redis version: Linux gentoo 4.12.12-gentoo #1 SMP Wed Oct 4 09:05:50 CST 2017 x86_64 Virtual CPU a7769a6388d5 GenuineIntel GNU/Linux Redis server v=4.0.2 sha=00000000:0 malloc=jemalloc-3.6.0 bits=64 build=4504b17bcfd3837e