Single symbol in random position with Brute-Force attack

[Snoopy]

i this case i would say you should use a maskfile with 8 lines like you said

?l?u?d,?s,?1?1?1?1?1?1?1?2
?l?u?d,?s,?1?1?1?1?1?1?2?1

or

?l?u?d,?1?1?1?1?1?1?1?s
?l?u?d,?1?1?1?1?1?1?s?1


and so on, then use this maskfile instead of your singlemask on commandlin