check process memory usage on Linux

1. Use this tool:

  http://www.pixelbeat.org/scripts/ps_mem.py 

 [root@web2 ~]# python ./ps_mem.py
 Private  +   Shared  =  RAM used       Program

   4.0 KiB +  10.5 KiB =  14.5 KiB       klogd
   4.0 KiB +  16.5 KiB =  20.5 KiB       udevd
   4.0 KiB +  23.0 KiB =  27.0 KiB       glusterd
 76.0 KiB +  17.0 KiB =  93.0 KiB       init
 84.0 KiB +  11.0 KiB =  95.0 KiB       syslogd
100.0 KiB +  22.0 KiB = 122.0 KiB       agetty
436.0 KiB +  13.0 KiB = 449.0 KiB       klogd1
392.0 KiB + 265.0 KiB = 657.0 KiB       sendmail.sendmail (2)
   1.0 MiB +  66.5 KiB =   1.1 MiB       bash
   1.5 MiB + 268.0 KiB =   1.8 MiB       sshd (2)
  3.0 MiB + 847.0 KiB =   3.8 MiB       crond (13)
137.2 MiB +  11.0 MiB = 148.2 MiB       httpd (34)
253.0 MiB +   5.4 MiB = 258.4 MiB       php (18)
---------------------------------
                        414.7 MiB
=================================

2.

htop

Similar to the top command, the htop command also shows memory usage along with various other details.

The header on top shows cpu usage along with RAM and swap usage with the corresponding figures.