DOS's attrib command does not allow you to set the attributes for hidden and system files. Also, it aborts if it encountered an error. So I wrote attr.

You can download the binary here and the source code here.

Here's the changelog:

attr changelog

Version 1.4 - 28 Feb 07:

	Enabled -n | --not-indexed + | -  Set/reset content not indexed bit
	Enabled -o | --offline     + | -  Set/reset offline bit
	Enabled -t | --temporary   + | -  Set/reset temporary bit

Version 1.3 - 14 Nov 06:

	Added display of attributes in the form 'arhsnot'
	Added -d | --directories        Set/reset bits on directories
	Added -y | --dry-run            Change nothing, just report what would change
	Added -i | --hide-attributes    Do not show attributes
	Improved error handling
	Processes *.* if no filespec is specified
	Return errorcode if an error occured (and --abort-on-error is set)
	Report on changed files only (unless -v is used)
	Skipped processing of . and .. directories

Version 1.2 - 19 Jul 06:

	Standardized version information across all programs

Version 1.1 - 08 Apr 06:

	Added -n | --not-indexed + | -  Set/reset content not indexed bit
	Added -o | --offline     + | -  Set/reset offline bit
	Added -t | --temporary   + | -  Set/reset temporary bit
	Added -e | --abort-on-error     Abort if an error occurs
	Added .rc and .ico files
	Improved build scripts
	Updated documentation
	
Version 1.0 - 12 Apr 04:

	Initial release

and here's the readme.txt:

attr - Version 1.4 - Feb 28 2007
Copyright (c) 2004-2007 Ross Smith II (http://smithii.com) All Rights Reserved

------------------------------------------------------------------------------

Usage: attr [options] filespec [filespec]

Options:
-a | --archive     + | -  Set/reset archive bit
-r | --readonly    + | -  Set/reset read only bit
-h | --hidden      + | -  Set/reset hidden bit
-s | --system      + | -  Set/reset system bit
-n | --not-indexed + | -  Set/reset content not indexed bit
-o | --offline     + | -  Set/reset offline bit
-t | --temporary   + | -  Set/reset temporary bit
-d | --directories        Set/reset bits on directories
-y | --dry-run            Change nothing, just report what would change
-i | --hide-attributes    Do not show attributes
-e | --abort-on-error     Abort if an error occurs
-R | --recursive          Scan directories recursively
-q | --quiet              Display less information
-v | --verbose            Display more information
-V | --version            Show version and copyright information and quit
-? | --help               Show this help message and quit

Works on hidden and system files.
Doesn't abort on error (unless you use the -e option).

When displaying attributes, the following characters are used:

Character Meaning
--------- -------
-		  The attribute is not set, and will not be changed
_         The attribute was set, and will be reset (turned off)
a         Archive     attribute is set, and will not be changed
r         Read-only   attribute is set, and will not be changed
h         Hidden      attribute is set, and will not be changed
s         System      attribute is set, and will not be changed
n         Not-indexed attribute is set, and will not be changed
o         Offline     attribute is set, and will not be changed
t         Temporary   attribute is set, and will not be changed
A         Archive     attribute is not set, and will be set
R         Read-only   attribute is not set, and will be set
H         Hidden      attribute is not set, and will be set
S         System      attribute is not set, and will be set
N         Not-indexed attribute is not set, and will be set
O         Offline     attribute is not set, and will be set
T         Temporary   attribute is not set, and will be set

------------------------------------------------------------------------------

Examples:

C:\>rem turn off archive bit on files in c:\
C:\>attr -a- 

C:\>rem turn off archive bit on files on drive c:
C:\>attr -a- -R

C:\>rem display what files have their archive bit set on drive c: (but don't change the bit):
C:\>attr -a- -R --dry-run *.*

C:\>rem display what files don't have their archive bit set on drive c: (but don't change the bit):
C:\>attr -a+ -R --dry-run *.*

------------------------------------------------------------------------------

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.