In this tutorial, I will show a shell script to check memory usage for each program or application on Linux. The 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.
This script use 2 files ie ‘/proc/../status’ (to get the name of the process) and ‘/proc/../smaps’ for memory statistic of process. Then the script will convert all data into Kb, Mb, Gb. Also, make sure you install bc command.
You can download linux memory usage script in pdf version and the script is also available in Github.
Shell Script to Check Memory Usage
Check the following script which calculates memory usage and print outputs.
#!/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 "tttttt `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
Shell Script Output
I have named this script as ‘memstat.sh’ and find the output by running the script as follows:
[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 ~]#
