[absmiths]

What are the s's? Is that setuid root? If so, how do I remove or re-add it?

[absmiths]

I figured this one out with the man page. The s is the setuid bit for that group (either owner or group, but not world I think).

Anyway, you set it by adding 4000 to the permission for owner setuid or 2000 for the group setuid.

E.G., chmod 755 looks like this:

-rwxr-xr-x

chmod 4755 looks like this:
-rwsr-xr-x

and chmod 2755 looks like this:
-rwxr-sr-x

For some reason, 4666 and 2666 are legal modes even though the file is not executable. chmod 4666 and 2666 look like this, although it seems contradictory:

-rwSrw-rw-
-rw-rwSrw-

[EmmEff]

Another trick is:

chmod u+s <filename>

for adding the setuid bit without changing the existing (other) permissions.

Or:

chmod g+s <directory>

for adding the setgid bit.