Linux Shell Script To Find Memory Usage Of An Application/Program In Linux

Memstat.sh is a shell script that calculates linux memory usage for each program / application. Script outputs shared and private memory for each program running in linux. Since memory calculation is bit complex, this shell script tries best to find more accurate results. Script use 2 files ie /proc//status (to get name of process) and /proc//smaps for memory statistic of process. Then script will convert all data into Kb, Mb, Gb. Also make sure you install bc command. 

Memstat.sh Shell Script

#!/bin/bash
# Make sure only root can run our script

if [ "$(id -u)" != "0" ]; then
echo “This script must be run as root” 1>&2
exit 1
fi

### Functions
#This function will count memory statistic for passed PID
get_process_mem ()
{
PID=$1
#we need to check if 2 files exist
if [ -f /proc/$PID/status ];
then
if [ -f /proc/$PID/smaps ];
then
#here we count memory usage, Pss, Private and Shared = Pss-Private
Pss=`cat /proc/$PID/smaps | grep -e “^Pss:” | awk ‘{print $2}’| paste -sd+ | bc `
Private=`cat /proc/$PID/smaps | grep -e “^Private” | awk ‘{print $2}’| paste -sd+ | bc `
#we need to be sure that we count Pss and Private memory, to avoid errors
if [ x"$Rss" != "x" -o x"$Private" != "x" ];
then

let Shared=${Pss}-${Private}
Name=`cat /proc/$PID/status | grep -e “^Name:” |cut -d':’ -f2`
#we keep all results in bytes
let Shared=${Shared}*1024
let Private=${Private}*1024
let Sum=${Shared}+${Private}

echo -e “$Private + $Shared = $Sum \t $Name”
fi
fi
fi
}

#this function make conversion from bytes to Kb or Mb or Gb
convert()
{
value=$1
power=0
#if value 0, we make it like 0.00
if [ "$value" = "0" ];
then
value=”0.00″
fi

#We make conversion till value bigger than 1024, and if yes we divide by 1024
while [ $(echo “${value} > 1024″|bc) -eq 1 ]
do
value=$(echo “scale=2;${value}/1024″ |bc)
let power=$power+1
done

#this part get b,kb,mb or gb according to number of divisions
case $power in
0) reg=b;;
1) reg=kb;;
2) reg=mb;;
3) reg=gb;;
esac

echo -n “${value} ${reg} ”
}

#to ensure that temp files not exist
[[ -f /tmp/res ]] && rm -f /tmp/res
[[ -f /tmp/res2 ]] && rm -f /tmp/res2
[[ -f /tmp/res3 ]] && rm -f /tmp/res3

#if argument passed script will show statistic only for that pid, of not – we list all processes in /proc/ #and get statistic for all of them, all result we store in file /tmp/res
if [ $# -eq 0 ]
then
pids=`ls /proc | grep -e [0-9] | grep -v [A-Za-z] `
for i in $pids
do
get_process_mem $i >> /tmp/res
done
else
get_process_mem $1>> /tmp/res
fi

#This will sort result by memory usage
cat /tmp/res | sort -gr -k 5 > /tmp/res2

#this part will get uniq names from process list, and we will add all lines with same process list
#we will count nomber of processes with same name, so if more that 1 process where will be
# process(2) in output
for Name in `cat /tmp/res2 | awk ‘{print $6}’ | sort | uniq`
do
count=`cat /tmp/res2 | awk -v src=$Name ‘{if ($6==src) {print $6}}’|wc -l| awk ‘{print $1}’`
if [ $count = "1" ];
then
count=””
else
count=”(${count})”
fi

VmSizeKB=`cat /tmp/res2 | awk -v src=$Name ‘{if ($6==src) {print $1}}’ | paste -sd+ | bc`
VmRssKB=`cat /tmp/res2 | awk -v src=$Name ‘{if ($6==src) {print $3}}’ | paste -sd+ | bc`
total=`cat /tmp/res2 | awk ‘{print $5}’ | paste -sd+ | bc`
Sum=`echo “${VmRssKB}+${VmSizeKB}”|bc`
#all result stored in /tmp/res3 file
echo -e “$VmSizeKB + $VmRssKB = $Sum \t ${Name}${count}” >>/tmp/res3
done

#this make sort once more.
cat /tmp/res3 | sort -gr -k 5 | uniq > /tmp/res

#now we print result , first header
echo -e “Private \t + \t Shared \t = \t RAM used \t Program”
#after we read line by line of temp file
while read line
do
echo $line | while read a b c d e f
do
#we print all processes if Ram used if not 0
if [ $e != "0" ]; then
#here we use function that make conversion
echo -en “`convert $a` \t $b \t `convert $c` \t $d \t `convert $e` \t $f”
echo “”
fi
done
done < /tmp/res

#this part print footer, with counted Ram usage
echo "--------------------------------------------------------"
echo -e "\t\t\t\t\t\t `convert $total`"
echo "========================================================"

# we clean temporary file
[[ -f /tmp/res ]] && rm -f /tmp/res
[[ -f /tmp/res2 ]] && rm -f /tmp/res2
[[ -f /tmp/res3 ]] && rm -f /tmp/res3

Memstat.sh Shell Script Output

[root@centos-cluster-node1 ~]# ./memstat.sh
Private + Shared = RAM used Program
36.26 mb + 268.00 kb = 36.52 mb python
20.49 mb + 238.00 kb = 20.72 mb iscsiuio
4.78 mb + 451.00 kb = 5.22 mb rgmanager(2)
3.62 mb + 283.00 kb = 3.90 mb NetworkManager
2.53 mb + 1.36 mb = 3.89 mb sshd(3)
2.30 mb + 355.00 kb = 2.64 mb multipathd
2.25 mb + 176.00 kb = 2.42 mb hald
1.69 mb + 298.00 kb = 1.98 mb iscsid(2)
1.45 mb + 432.00 kb = 1.87 mb dhclient(3)
1.62 mb + 161.00 kb = 1.77 mb cupsd
704.00 kb + 819.00 kb = 1.48 mb udevd(3)
856.00 kb + 554.00 kb = 1.37 mb bash(2)
1.00 mb + 314.00 kb = 1.31 mb qmgr
984.00 kb + 314.00 kb = 1.26 mb pickup
976.00 kb + 316.00 kb = 1.26 mb master
1.07 mb + 21.00 kb = 1.09 mb rsyslogd
804.00 kb + 240.00 kb = 1.01 mb modem-manager
904.00 kb + 40.00 kb = 944.00 kb pcscd
804.00 kb + 33.00 kb = 837.00 kb ricci
788.00 kb + 38.00 kb = 826.00 kb dbus-daemon
660.00 kb + 32.00 kb = 692.00 kb crond
536.00 kb + 69.00 kb = 605.00 kb rpc.statd
528.00 kb + 46.00 kb = 574.00 kb init
216.00 kb + 357.00 kb = 573.00 kb saslauthd(5)
544.00 kb + 21.00 kb = 565.00 kb wpa_supplicant
484.00 kb + 72.00 kb = 556.00 kb mingetty(6)
316.00 kb + 58.00 kb = 374.00 kb rpcbind
116.00 kb + 237.00 kb = 353.00 kb memstat.sh
328.00 kb + 13.00 kb = 341.00 kb auditd
248.00 kb + 84.00 kb = 332.00 kb hald-runner
312.00 kb + 8.00 kb = 320.00 kb oddjobd
216.00 kb + 81.00 kb = 297.00 kb hald-addon-stor
196.00 kb + 88.00 kb = 284.00 kb hald-addon-inpu
272.00 kb + 4.00 kb = 276.00 kb rpc.idmapd
176.00 kb + 52.00 kb = 228.00 kb hald-addon-acpi
——————————————————–
98.57 mb
========================================================
[root@centos-cluster-node1 ~]#