Use the following command to check the memory usage of a specific process.

• cat /proc/<process ID>/status

You will get the following output.

Name:	httpd
State:	S (sleeping)
SleepAVG:	98%
Tgid:	29927
Pid:	29927
PPid:	3407
TracerPid:	0
Uid:	48	48	48	48
Gid:	48	48	48	48
FDSize:	64
Groups:	48 
VmPeak:	  417648 kB
VmSize:	  417392 kB
VmLck:	       0 kB
VmHWM:	  104592 kB
VmRSS:	   97572 kB
VmData:	  124316 kB
VmStk:	     332 kB
VmExe:	     312 kB
VmLib:	   24856 kB
VmPTE:	     820 kB
StaBrk:	2aaf805ad000 kB
Brk:	2aaf807cc000 kB
StaStk:	7fff14cd3b80 kB
Threads:	1
SigQ:	0/16384
SigPnd:	0000000000000000
ShdPnd:	0000000000000000
SigBlk:	0000000000000000
SigIgn:	0000000001001000
SigCgt:	000000018c00466b
CapInh:	0000000000000000
CapPrm:	0000000000000000
CapEff:	0000000000000000
Cpus_allowed:	00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000001
Mems_allowed:	00000000,00000001

Done =)

Reference: StackOverflow – Linux: How to measure actual memory usage of an application or process?