after a reboot i could not start mysql anymore.
[ERROR] mysqld: Can't create/write to file '/usr/local/var/mysql/aria_log_control' after a while i noticed that man was not working anymore:
man-db: error while loading shared libraries: libmandb-2.8.1.so
slowly i started to understand that something serious did happen to the system. after executing
chmod o+x .
from / directory, also inside /lib/ and /lib/mysql/ and yes, man and mysql did work again!
afterwards i executed something, that i SHOULDNT execute:
chmod -R 755 /sbin /usr/ /lib /lib64 /var
as someone recommended it as you can see in the link to fix permissionproblems, and my courier-auth-daemon did not start anymore, while mysql was running again.
after a reboot ssh did not let me in anymore, cause the private key had 755 aswell.
i realized that the ownership for / was not root anymore, but another user, cause of a malfunction of a php-script. i ended up syncing the permissions from a backup back to the system using the find command as described here:
be carfeul, it took me a lot of time, to get another backup, cause i missunderstood the commands of this link. it means
find . -exec chmod -v --reference='{}' /path/to/target/'{}' \;copies the permissions from . (the folder you are in) to the /path/to/target/. – and not vice versa.
to copy the permissions from a target to the folder you’re currently inside, you need to use
find . -exec chmod -v –reference=/path/to/target/'{}’ ‘{}’ \;
…same as for chown….
so, in general: if you run into mysql-permission-problems check the rights of the entire hirachy and the owner of / ! this may help!