⌘I Get Infoand scroll down to the bottom, expanding Sharing & Permissions.
If there is a file inside a directory, and you have read access to the file but not read access to the directory, you can still read the file.
chmod 775, you can do things like:
chmod u+x: user executable
chmod a+x: user, group, AND other executable
chmod o-rwx: other NOT readable, writable, or executable
chmod u+s ...
Always executes as the user who owns the file
On a directory? DON'T KNOW
chmod g+s ...
Always executes as the group who owns the file
On a directory, any files created there will have the group ownership set to that of the directory owner
chmod +t directory
On a directory, only allows owner to delete or rename contents... used for
/tmp and places like that
umaskdefines the default settings for permissions on stuff you create.
777, and on a file,
Your umask is subtracted from the defaults, so with the
default umask of
775 (other can't write)
664 (nobody can execute, other can't write)