filedate2nameprefix.sh

#!/bin/bash


for i in "$@"
do

    dn=$(dirname "$i")
    bn=$(basename "$i")

    if grep -Eq '^[0-9]{4}-[0-9]{2}-[0-9]{2}_' <<< "$bn" 
    then
        echo "# date existing on $bn ($i)"
        continue
    fi

    dt="$(stat -c %y "$i" | cut -d ' ' -f 1)_"

    echo -n '# mv says:'
    mv -v -u "$i" "$dn/$dt$bn"
    echo "mv \"$dn/$dt$bn\" \"$i\" # to reverse"

done