The script
file.sh was already launched by default by another script in the rcN.d directory, let's call it
S01xxx.
Another solution (avoiding to use a pre-existent script
file.sh) is to substitute the same script
S01xxx with another where the unique difference is to check if a particularly file
file2.sh exists, and then execute it.. You can remove the same
file2.sh by himself at the end of the
file2.sh once it has executed one time..