1. If you reinstalled the OS, you must manually recreate users and groups or restore the /etc/passwd and /etc/group files. More files are required if you where using enhanced security.
2. Don't grant world write access to files, create a common group for users that need to write to files/directories and add the users to that group. You can use something:
chown -R root.group directory/
chmod -R root.group directory/
To apply permissions recursivelly. You can also do a "find":
find . -type f -exec chown root.group {} \;
find . -type f -exec chmod 664 {} \;
find . -type d -exec chown root.group {} \;
find . -type f -exec chmod 775 {} \;
3. Yes, environmental variables must be restored from a backup if you have one. They can be in /etc/profile or in the user $HOME/.profile (depending of the shell).
Por que hacerlo dificil si es posible hacerlo facil? - Why do it the hard way, when you can do it the easy way?
