3 Unix Shell Scripts – User Activity, View Processes, Display Memory

You might find the following three Linux / Unix shell scripts helpful.

• Display processes based on either %CPU or Memory Usage.
• Display which user is utilizing the CPU the most.
• Display system’s memory information – total, used and free.

1. List Processes based on %CPU and Memory Usage

This script list the processes based on %CPU and Memory usage, with out argument (by default), If you specify the argument (cpu or mem), it lists the processes based on CPU usage or memory usage.

$ cat processes.sh
#! /bin/bash
#List processes based on %cpu and memory usage

echo "Start Time" `date`
# By default, it display the list of processes based on the cpu and memory usage #
if [ $# -eq 0 ]
then

	echo "List of processes based on the %cpu Usage"
	ps -e -o pcpu,cpu,nice,state,cputime,args --sort pcpu  # sorted based on %cpu
	echo "List of processes based on the memory Usage"
	ps -e -orss=,args= | sort -b -k1,1n # sorted bases rss value

# If arguements are given (mem/cpu)
else
	case "$1" in
	mem)
	 echo "List of processes based on the memory Usage"
 	 ps -e -orss=,args= | sort -b -k1,1n
	 ;;
 	cpu)
	 echo "List of processes based on the %cpu Usage"
	 ps -e -o pcpu,cpu,nice,state,cputime,args --sort pcpu
	 ;;
 	*)
		echo "Invalid Argument Given \n"
		echo "Usage : $0 mem/cpu"
		exit 1
 	esac	

fi
echo "End Time" `date`
exit 0

You can execute the above script as shown below.

$ processes.sh

$ processes.sh mem

$ processes.sh cpu

2. Display Logged in users and who is using high CPU percentage

This script displays few information about the currently logged in users and what they are doing.

$ cat loggedin.sh
#! /bin/bash

w > /tmp/a

echo "Total number of unique users logged in currently"
cat /tmp/a|  sed '1,2d' | awk '{print $1}' | uniq | wc -l
echo ""

echo "List of unique users logged in currently"
cat /tmp/a | sed '1,2d'|  awk '{print $1}' | uniq
echo ""

echo "The user who is using high %cpu"
cat /tmp/a | sed '1,2d' | awk   '$7 > maxuid { maxuid=$7; maxline=$0 }; END { print maxuid, maxline }' 

echo ""
echo "List of users logged in and what they are doing"
cat /tmp/a

$ ./loggedin.sh
Total number of unique users logged in currently
4

List of unique users logged in currently
john
david
raj
reshma

The user who is using high %cpu
0.99s reshma   pts/5    192.168.2.1  15:26    3:01   1.02s  0.99s custom-download.sh

List of users logged in and what they are doing
 15:53:55 up 230 days,  2:38,  7 users,  load average: 0.19, 0.26, 0.24
USER     TTY      FROM              LOGIN@   IDLE   JCPU   PCPU WHAT
john     pts/1    192.168.2.9   14:25    1:28m  0.03s  0.03s -bash
john     pts/2    192.168.2.9   14:41    1:11m  0.03s  0.03s -bash
raj      pts/0    192.168.2.6   15:07    9:08   0.11s  0.02s -bash
raj      pts/3    192.168.2.6   15:19    29:29  0.02s  0.02s -bash
john     pts/4    192.168.2.91  15:25    13:47  0.22s  0.20s vim error_log
reshma   pts/5    192.168.2.1   15:26    3:01   1.02s  0.99s custom-download.sh

3. Display Total, Used and Free Memory

The following script displays the total, used and free memory space.

$ cat mem.sh
#! /bin/bash

# Total memory space details

echo "Memory Space Details"
free -t -m | grep "Total" | awk '{ print "Total Memory space : "$2 " MB";
print "Used Memory Space : "$3" MB";
print "Free Memory : "$4" MB";
}'

echo "Swap memory Details"
free -t -m | grep "Swap" | awk '{ print "Total Swap space : "$2 " MB";
print "Used Swap Space : "$3" MB";
print "Free Swap : "$4" MB";
}'

$ ./mem.sh
Memory Space Details
Total Memory space : 4364 MB
Used Memory Space : 451 MB
Free Memory : 3912 MB
Swap memory Details
Total Swap space : 2421 MB
Used Swap Space : 0 MB
Free Swap : 2421 MB