1. If you have a wordlists but want to transform it (for eg add numbers behind) can edit /etc/john/john.conf and add the following:
   [List.Rules:AddNumber]
# Add two numbers to the end of each password
$ [0-9]$[0-9]
   Subsequently run
   john --wordlist=before.txt --rules=AddNumber --stdout > after.txt
   For more info read here https://miloserdov.org/?p=5477​
2. Own custom wordlist with special pattern: crunch minchar maxchar structure. For eg if we want a 4-6 characters password, first 4 is uppercase letter next 4 is number can use crunch 4 6 -t ,,,,%%%%. If size ok then only run crunch 4 6 -t ,,,,%%%% -o output.txt
@ lowercase
   , uppercase
   % numeric
   ^ special characters including space