#!/bin/bash
echo "user	rss_mbytes(desc sort)	[total|pid stime cmd]"

ps -e -o user,rss,pid,stime,cmd | perl -lne '($user, $rss, $cmd) = (/^(\S+)\s+(\d+)\s+(.*)/);
$usage{$user}{total} += $rss;
$usage{$user}{$cmd} += $rss;
END {
  for $u (sort { $usage{$b}{total} <=> $usage{$a}{total} } keys %usage) {
    $uu = $usage{$u};
    for $c (sort { $uu->{$b} <=> $uu->{$a} } keys %$uu) { 
      printf "$u\t%.1f\t$c\n", $uu->{$c} / 1024
    }
  }
}' #| cut -c1-100 | ya paste
