If you're trying to write to a file in MySQL, you can get an error which says
Can't create/write to file <filename>
If you're doing this from Python, you can get aa mysql_exceptions.InternalError Errcode 13.
This may be because AppArmor is preventing the write.
If you want be to write recursively to a particular path and are using Ubuntu -
Append
/usr/sbin/mysqld {
...
/path/to/write/to/** rw,
}
to the file
/etc/apparmor.d/usr.sbin.mysqld
and restart apparmor
$ sudo /etc/init.d/apparmor restart
If you just want to specify a particular file, you can omit the /**.