Derez uses the access times, time last read not time last written, of the files to determine their staleness. The default number of days since last access is 180 days, but this can be changed using the -t option. If no directory list is given to derez it searches current directory, except the subdirectory MORGUE. The -t option and a directory list can be used to give special handling to antisocial users.
Derez can be defeated by using find and readbyte to find and read all of the files in a directory tree. Although doing this might be reasonable for some directory that you haven't looked at in some time, but will be using in a few days, doing this to all of your files to defeat derez is considered antisocial and is dealt with using back up options. These options include: changing derez's definition of staleness from several months to one day or less for the antisocial user, archiving directories of the antisocial user by hand and removal of the antisocial user's account from the machine. If you are going to use readbyte to save some files from derez, you should check with root first to make sure that the action won't be interpreted as antisocial.
The best way to avoid getting derez'ed is to actively archive your stale files onto tape using tar and keep them off line. If a user actively archives his stale files onto tape, a rather large disk usage for truly active files will be tolerated.
Although derez was written for root's use, an individual user can use it to find and archive his stale files. This is done by making a subdirectory with the name MORGUE in any directory you would like to archive the descendant stale files. You then run derez. Derez will create a list of stale files, with the name MORGUE/DEREZ and then move the stale files into the directory MORGUE. If a file that is removed is the last file in it's parent directory, the parent directory is removed. The contents of the morgue directory can be archived using tar and then removed from the disk. The use of derez for stale file control is highly recommended. Scratch tapes can be found next to the system console.
Files that have been derez'ed by root can be recovered from the archive tape using tar. To recover all one's stale files without moving some or all off line with personal archive tapes is considered antisocial.