chmod (GNU fileutils) 4.0.35

[David van Gorkom]

Dear ladies and gentlemen,

when executing

chmod +w file
or
chmod -w file

this has only effect on the write bit of the user - not to all (i.e. group 
and others are not affected) (whereas +r,-r and +x,-x are working as expected 
and set the permission for all)

Best regards,
David van Gorkom.


P.S.:
I'm not sure if this is a bug - my reference was the freebsd manual for 
chmod, but I tested chmod (GNU fileutils) 4.0.35 under Linux.

http://www.freebsd.org/cgi/man.cgi?chmod

The relevant part from the chmod manual is:

[...]

     The symbolic mode is described by the following grammar:

   mode ::= clause [, clause ...]
   clause::= [who ...] [action ...] action
   action::= op [perm ...]
   who::= a | u | g | o
   op::= + | - | =
   perm ::= r | s | t | w | x | X | u | g | o

[...]

     The op symbols represent the operation performed, as follows:

     +   If no value is supplied for perm, the ``+'' operation has no
   effect.  If no value is supplied for who, each permission bit spec-
   ified in perm, for which the corresponding bit in the file mode
   creation mask is clear, is set.  Otherwise, the mode bits repre-
   sented by the specified who and perm values are set.

[...]