VMSTAT

vmstat 1

htop

sudo apt-get install -y htop
sudo htop

atop

sudo apt-get install atop -y
sudo atop

How to Find the Most Memory taking process in Ubuntu Linux

Some Times system administrators need to kill the memory eater process. When your system become slower, check the following command and find the memory eater.

Open a terminal and Type the following command

ps aux | sort -nrk 4 | head

Sysstat

sudo apt-get install sysstat -y

mpstat -> contained in sysstat

mpstat 1 => mpstat every second

Memory monitoring of a give Process

cat /proc/meminfo

System memory allocation

free

empty / free up memory caches
To free pagecache:
echo 1 > sudo /proc/sys/vm/drop_caches

To free dentries and inodes:
echo 2 > sudo /proc/sys/vm/drop_caches

To free pagecache, dentries and inodes:
echo 3 > sudo /proc/sys/vm/drop_caches

As this is a non-destructive operation and dirty objects are not freeable, the user should run “sync” first!

This was originally found @ http://www.linuxinsight.com/proc_sys_vm_drop_caches.html
Loop free memory bash
while true; do free -m; sleep 1; done
while :; do free -m; sleep 1; done

Memory & CPU Utilisation
ps -eo pcpu,%mem,cmd|sort -k2 -r

ps -eo pcpu,%mem,cmd|sort -k2 -r|head -3

See also http://www.unix.com/shell-programming-scripting/65947-memory-cpu-utilization-process.html


top -p 
top -p 20832

process id from name
ps -ef | grep w.py|grep -v grep | awk '{print $2}'

top for only
top -p `ps -ef | grep w.py|grep -v grep | awk '{print $2}'` one process by name

Machine CPU - using ps aux
while :; do ps aux|awk 'NR > 0 { s +=$3 }; END {print s"%"}'; sleep 1; done

See also: http://bashscripts.org/forum/viewtopic.php?f=15&t=1237 and http://www.linuxquestions.org/questions/linux-newbie-8/how-to-get-cpu-usage-of-a-process-63726/
Process CPU - using ps uax
while :; do ps aux|grep w.py|awk 'NR > 0 { s +=$3 }; END {print s"%"}'; sleep 1; done
=> very inaccurate

Process CPU - using top
while :; do top -c -b -n 1|grep w.py; sleep 1; done
=> this is more accurate

Even better!
#while :; do top -c -b -n 1|grep w.py|grep -v grep|awk '{print $10}'; sleep 1; done

while :; do top -c -b -n 1|grep w.py|grep -v grep|awk '{print $9}'; sleep 1; done

while :; do i=$((i+1)); echo $i ; top -c -b -n 1|grep w.py|grep -v grep|awk '{print $9}'; sleep 1; don


Load - General
w|grep load

Checking your server load using bash

Load - Using uptime
while :; do uptime | awk '{print $10}'; sleep 1; done

#!/bin/bash
loadavg=`uptime | awk '{print $10}'`
# bash doesn't understand floating point
# so convert the number to an interger
thisloadavg=`echo $loadavg|awk -F \. '{print $1}'`
if [ "$thisloadavg" -ge "2" ]; then
 echo "Busy - Load Average $loadavg ($thisloadavg) "
 top -bn 1
else
 echo "Okay - Load Average $loadavg ($thisloadavg) "
fi

References
1. http://www.linuxquestions.org/questions/programming-9/check-server-load-with-bash-703464/

2. http://freetofeel.com/page3/

3. http://www.cyberciti.biz/tips/how-do-i-find-out-linux-cpu-utilization.html

4. http://www.shibuvarkala.com/2010/06/how-to-find-most-memory-taking-process.html