[root@server ~]# free -m
             total       used       free     shared    buffers     cached
Mem:          2048       2033         14          0         73       1398
-/+ buffers/cache:        561       1486
Swap:         2047         11       2036

[root@server ~]# ps aux | awk '{sum+=$6} END {print sum / 1024}'
1475.52

pmap -d PID

ps -eo size,pid,user,command --sort -size | awk '
  { hr=$1/1024 ; printf("%13.2f Mb ",hr) }
  { for ( x=4 ; x<=NF ; x++ ) { printf("%s ",$x) } print "" }
  ' | awk '{total=total + $1} END {print total}'

#!/bin/bash
total_mem=0

printf "%-10s%-10sn" User MemUsage

while read u m
do
        [[ $old_user != $u ]] && {  printf "%-10s%-0.1fn" $old_user $total_mem;
                                    total_mem=0; }
        total_mem="$(echo $m + $total_mem | bc)"
        old_user=$u

done < <(ps --no-headers -eo user,%mem| sort -k1)

#EOF

# smem -t
  PID User     Command                         Swap      USS      PSS      RSS
...
10593 root     /usr/lib/chromium-browser/c        0    22868    26439    49364
11500 root     /usr/lib/chromium-browser/c        0    22612    26486    49732
10474 browser  /usr/lib/chromium-browser/c        0    39232    43806    61560
 7777 user     /usr/lib/thunderbird/thunde        0    89652    91118   102756
-------------------------------------------------------------------------------
  118 4                                       40364   594228   653873  1153092

# smem -tw
Area                           Used      Cache   Noncache
firmware/hardware                 0          0          0
kernel image                      0          0          0
kernel dynamic memory        345784     297092      48692
userspace memory             654056     181076     472980
free memory                   15828      15828          0
----------------------------------------------------------
                            1015668     493996     521672