Use hashcat command using only lower and upper case letters

[RobbieRich]

Me again … what if I already know a part of the password , like “abc” somewhere in the middle ? 

hashcat -m xxx -a 3 -1 ?l?u hashfile ?1?1?1?1?1?1?1?1

Thanks for the swift reply ! Does the ?1 do it for upper and lowercase letters ?
And ?l?u what does that do ?
Sorry am noobie

https://hashcat.net/wiki/