1. at first basic check by one command
In output we can see utilization of memory and and swap. we can change output with -b bytes -k kilobytes instead of -m megabytes. Option -t is used for showing memory with swap (-t as total).
# free -tm total used free shared buffers cached Mem: 128393 82606 45787 0 9873 40943 -/+ buffers/cache: 31789 96604 Swap: 34815 4773 30042 Total: 163209 87379 75830 #
If we are not satisfied with this output we can be more detailed by next scripts.