I want to change directory and file creation modes '2770' and '2750', respectively. The '2' is the SUID bit and I want this 'cause I need that directories and files has the same owner and group that the my dokuwiki's root directory.
When I try to change this, dokuwiki report this error:
"Settings not updated due to an invalid value, please review your changes and resubmit.
The incorrect value(s) will be shown surrounded by a red border."
But 2770 and 2750 is a valid value to chmod. :-)
Erm, AFAIK the setuid bit makes only sense if you want a program to be executed under the user who owns the program. For example passwd on a Linux system is owned by root, but every user can use it because the setuid bit is set. I think what you mean is the setgid bit. However, you don't need to set it for each new file/directory. It should be enough to set the setgid bit for data/pages data/cache data/index data/attic data/meta.
Use a leading zero (02770 or 02750), the input only accepts octal values as chmod only accepts integers to octal base.