OK, first objection: you should definitely not use backticks any more. They are a B-A-D habit. Use the modern subshell command instead: "$(....)".

Code:

TODAY=$(date +%s)

Perfect would be to type your variables:

Code:

typeset -i TODAY=$(date +%s)

The same goes for for the other variables. Personally (but that is only me) i use a sort-of "hungarian style notation" to keep track of what is in my variables: suffix "i" is for integers, "f" for files/paths, "ch" for characters/strings, etc..
I would write, for instance:

Code:

typeset    fInfile="/path/to/some/file"
typeset -i iToday=1392921191
typeset    chToday="Monday"

Even if i have two different representations for "today" (once a Unix time, once a day of the week) i can tell that "iToday" is an integer and "chToday" holds a string.


Don't do that. I don't mean the backticks this time (you shouldn't use them either, see above), but here you shouldn't forego the capability of any modern shell to deal with integers:

Code:

(( OFFSET = TODAY - TS ))

will do the same and with a lot less effort. It is also easier to read, IMHO.

Well, have a look at the output of ls -1 $BCK_DIR and tell me what you see. The list should look like this:

Code:

# ls -1 /tmp
file1
another.file
yet.another.file
a_file_too
[...]

Do you see any path? I don't. So, inside your loop the variable "FILE" holds only a filename, not the complete path to it, yes? It will hold, for instance,
filetest.txt_19-02-2014_17h58m33+1392829113, but not /Volumes/BACKUP/BCK_DATA/_ARCHIVES_/filetest.txt_19-02-2014_17h58m33+1392829113.

Now, you try to move this file to a certain other location. First problem: you can call this script from anywhere, but chances are the file you looked for in "$BCK_DIR" is not in the current directory. To make your script more robust use:

Code:

     if [ $OFFSET -gt $NDAYS ] ; then
          mv "${BCK_DIR}/${FILE}" "$TRASHDIR"
     fi

Now it will work from anywhere.

Second: you do not take care if "$TRASHDIR" is pointing to any valid directory and if you (or your script) is allowed to write to it. You should check that before you even attempt to move files there:

Code:

if [ ! -d "$TRASHDIR" ] ; then
     print -u2 - "Error: $TRASHDIR does not exist or is not a directory."
     exit 2
fi

Alternatively you could try to create the directory, let the user specify another directory, do whatever - but you should definitely check every step your script undertakes. You do not have to correct every problem, but you should recognize and report it.

The same goes for accessibility: to check if the directory is there is not enough, you have to be able to access it:

Code:

touch "${TRASHDIR}/$$"
if [ $? -gt 0 ] ; then
     print -u2 - "Error: $TRASHDIR cannot be written to."
     exit 2
else
     rm "${TRASHDIR}/$$"
fi

Some (like me) take such cautiousness to religious heights. You could also check: availability of i-nodes, having enough space in the filesystem to copy files there, and a lot of things more. What i show you here is just the basics.

This looks tedious at first, but you will be rewarded with having absolutely unbreakable scripts which never produce an undefined state. They will always be clear about what went wrong and why they were unable to do their task.

I hope this helps.

bakunin