Re: chmod drwxrwxrwT

[Bob Proulx]

Mario Lombardo wrote:
> In the last triplet, a capital "T" isn't discussed on the man page.  I know 
> it's sticky, but it means something different from drwxrwxrwt.  Where can I 
> get more info on this?  I'd like to learn.

It actually means exactly the same thing there, it is still the sticky
bit.  But the difference is whether it is an executable file or a
directory.  That difference means something.

If you see 'T' then the execute bit is not set.  Very unusual.  That
is probably not what is wanted.  Same for the suid and sgid bits and
mode bit 'S'.

 x is x
 x+t is t
 t by itself is T

One place where 't' it is very important is on directories.  /tmp is a
prime example.  In the context of a directory it means that only the
owner or the superuser can make changes.  This is needed for security
reasons.  On directories this prevents users from removing or renaming
a file unless they own the file or directory.  Shared writable areas
like /tmp need this.

Bob