[grep] Grep for beginning and end of line?

The tricky part is a regex that includes a dash as one of the valid characters in a character class. The dash has to come immediately after the start for a (normal) character class and immediately after the caret for a negated character class. If you need a close square bracket too, then you need the close square bracket followed by the dash. Mercifully, you only need dash, hence the notation chosen.

grep '^[-d]rwx.*[0-9]$' "$@"

See: Regular Expressions and grep for POSIX-standard details.