Linux check memory usage

If you're running Linux on low memory machine, you'll probably want to check its memory usage, and see which application or services used the most, and for those unused, you can terminate it.

Linux comes with few different command to check memory usage.

To check all your memory usages:
-#cat /proc/meminfo

To check memory usages in summary:
-vmstat

To check free memory size:
-free

To check free memory size in MB:
-free -m

Displays a line containing total free memory in MB:
-free -t -m