hashcat Forum

Hashcat.exe -D 1 --stdout -w 4 -j "c" -k "u" "first.txt" "second.txt"  output only first file without combination

you have to specify attackmode combinator

-a 1

otherwise hashcat will turn auto to -a 0 and these attack only supports ONE input file, so your second file second.txt and your rule -k "u" is ignored

btw:
you can remove -w 4, this option is for workload and --stdout doesnt really produce "work"

🤦🏻
Thank you.