find memory usage of a process linux code example

Example: linux show current memory usage

free
#------------------------------------------------------------
#total	Total installed memory
#used	Memory currently in use by running processes (used= total – free – buff/cache)
#free	Unused memory (free= total – used – buff/cache)
#shared	Memory shared by multiple processes
#buffers	Memory reserved by the OS to allocate as buffers when process need them
#cached	Recently used files stored in RAM
#buff/cache	Buffers + Cache
#available	Estimation of how much memory is available for starting new applications, without swapping.