Why do I have both root and mongodb permisssions?

Question

These are permissions

total 8
7351455 drwxr-xr-x  2 mongodb mongodb 4096 авг 21 10:36 .
7340101 drwxr-xr-x 69 root    root    4096 сеп  4 11:40 ..

for my /var/lib/mongodb

I am having problem with mongodb service,I found that I must run

sudo chown -R mongodb:mongodb /var/lib/mongodb

df -T shows

df -T
Filesystem     Type     1K-blocks     Used Available Use% Mounted on
udev           devtmpfs   8145248        0   8145248   0% /dev
tmpfs          tmpfs      1634684     1904   1632780   1% /run
/dev/sda5      ext4     244567356 79042556 153031796  35% /

I think it is ext4.

Why?

Answer 1

I suspect you ran

sudo chown -R mongodb:mongodb /var/lib/mongodb

and than you found yourself puzzled because ls -lia /var/lib/mongodb also showed this entry:

7340101 drwxr-xr-x 69 root    root    4096 сеп  4 11:40 ..

That doesn't mean chown didn't work. Every directory on a Unix-like system has these two entries: ., which is a hard link to the directory itself, and .., a hard link to its parent directory.

The above line from the output of ls refers to /var/lib/mongodb's parent directory, /var/lib, which is still owned by root (as it should!).

Actually, the entry

7351455 drwxr-xr-x  2 mongodb mongodb 4096 авг 21 10:36 .

confirms that chmod worked (or changed nothing because there was nothing to change).