home backup files vanish

[Nachteule]

Code:

cpb () {
                ar=0
                while read a; do
                        echo "$a" | grep -q ^[0-9] && { (($a > $ar)) && ar=$a; echo "$a"; }
                done | eval "$PIPECMD"
        }

See a couple of lines above

One of the program inside of the pipe seems to exit with an error code. The question is which one