$s = "1-6,27,105-170,512,670-675";;

@ranges = map{ 
    my( $lo, $hi ) = split '-', $_; 
    $hi //= $lo; 
    die 'Bad input' if $lo > $hi; 
    [ $lo, $hi ] 
} split ',', $s;;

print "@$_" for @ranges;;
1 6
27 27
105 170
512 512
670 675

##</code><code>##

qr[
    ^\s*                       ## from the start of the string, skip whitespace (if any)  
    (?: \d+ - \d+ )            ## then grab (at least one) pair of numbers separated by '-'
    (?:                        ## a group 
         \s* , \s*                 ### a comma, optionally preceded or followed by whitespace
         \d+ - \d+                 ### and another pair of numbers separated by '-'
    )*                         ## zero or more times
    \s*$                       ## to the end of string, optionally skipping whitespace if any
]x