OTP-sh/gen_sheet.sh

gen_sheet0() {
 n="${1:-8}"
 n="$(expr "$n" "*" "4")"                 #  ↓↓↓ octal
 grep -o "[[:digit:]]" -a /dev/urandom|grep [0-7]|
 head -n "$n"|
 tr -d "\n"|
 sed -e "s/..../&\n/g";
 echo;
}
gen_sheet() {
gen_sheet0 "$1"|tr -s "[:space:]"|tee sheet.txt
}