# Linux shadow passwd
# copy the two files and save them as passwd.txt and shadow.txt respectively.
unshadow passwd.txt shadow.txt > unshadowed.txt
john --rules --wordlist=/usr/share/wordlists/rockyou.txt unshadowed.txt
# hashcat
unshadow passwd.txt shadow.txt > unshadowed.txt
hashcat unshadowed.txt /usr/share/wordlists/rockyou.txt