how to check ram availability in a computer + linux command code example

Example: linux command to check memory usage in percentage

$ free -t | awk 'NR == 2 {printf("Current Memory Utilization is : %.2f%"), $3/$2*100}'
or
$ free -t | awk 'FNR == 2 {printf("Current Memory Utilization is : %.2f%"), $3/$2*100}'

Current Memory Utilization is : 20.42%