Please direct all questions, comments, and suggestions to:
Brent Hendricks
hendri27@cps.msu.edu

    The chmodder program is a small, simple utility for ensuring that
the permissions are set correctly in a directory hierarchy.  When run,
it descends through the directory tree and changes the permissions of
all the files and directories owned whomever ran the script.  (All
files/directories permissions will be changes if the user running the
script has root priviledges) The script can also be used to change the
group ownership of the contained files if a group name is specified on
the command line, and the user running the script is indeed a member
of the specified group.

Instructions: 
-Place the chmodder file in the highest directory level
of your tree.  (For EE482 design groups, this will be
/web/classes/ee482/designX where X is your design group number)

*NOTE* The following commands must be executed on a UNIX station, or
in a telnet session to a UNIX station.

-Change the group ownership of the chmodder script.  This is done with
the following command: chgrp XXXXX chmodder (where XXXX is your group
name).

-Change the permsissions of the chmodder program to be execuatable by
yourself and your group.  This is done with the following command:
chmod 770 chmodder

-Be sure that you are in the directory that contains the chmodder
program.  This is important.  The chmodder program begins recursing
through subdirectories from whatever directory YOU are currently in.

-Run the chmodder script simply be typing: chmodder.  It will then
recurse through the current directory and all subdirectories and
change the permission on oall of the files which you own.  If you
provide your group name as a command line argument it will also change
the group ownership.

-In order to keep the permissions correct, each member of the group
who adds/changes files will need to run the chmodder script before
he/she logs out.  While this may seem tedious, it beats changing
permissions manually on a large number of files.


Technical Notes: 
-This script was written in Perl5, and expects it to
be installed in /opt/bin.  This is true for the MSU engineering UNIX
labs.

-Directories will be given the permissions 2770 and all other files
will be given the permissions 660.  The exception to this is any
directory named web, and it's files and subdirectories.  Since these
files need to be world-accessible, directories in the web hierarchy
will be given permissions of 2775 and files will be given permissions
of 664.

-There is already a description of UNIX permissions on the EE482
website.  I do not wish to duplicate that material, however I would
like to mention the use of the setgid bit.  When this bit is set on a
directory file, files created in that directory will be owned by the
group which owns the directory. (This is not 100% true when accessing
files through DOS/Windows) This makes directories easier to maintain
because you don't need to issue a chgrp command for every file.  The
setgid bit is set by prepending a 2 to the permissions when executing
a chmod command.  This is why the chmodder script changes directories
to permissions 2770, and not 770.  When set, this bit will appear as
an 's' where the 'x' would normally appear in the group perssions
block.

Example:
drwxrws---   2 hendri27 ee482d3       512 Oct  3 14:27 reports
      ^ 

Whether or not the group has execute permissions is now indicated by
the case of 's'.  A lower-case 's' indicates the the groups HAS
execute permissions, whicle an uppercase 'S' indicates that the group
does not.