perl -E '@a=(0..9,A..Z,a..z);$_.=$a[rand@a]while 8>length;say'

##</code><code>##

perl6 -e 'say (0..9, "A".."Z", "a".."z").pick(8, :repl)'
JIEFoUyiq

##</code><code>##

$ pwgen -s 8 1
mUM6fAiz