Relational operators for floating point values in Unix Shell Scripting

Question

I'm writing a shell script to find out if any process is taking too much CPU utilization, then the script will send out a mail to the support team.

I have threshold limit as 25, and taking CPU Usage as:

cpuUsage=`ps -eo pcpu,pid,args | sort -k 1 -nr  | head -1`

Iterating over it to find out cpuUsage

for count in $cpuUsage
do
      CPUusageCount=$count
done

Then Checking CPUUsageCount with threshold limit as like this:

if [ $CPUusageCount -gt $THRESHOLD_LIMIT ];
then 
 #Sending mail to Support group
fi

Here I'm facing an error message: Integer expression expected at if [ $CPUusageCount . Can't we use -gt to validate floating point numbers? Please help me how to achieve it?

Answer 1

You could decide to chop the fractional part off the number, and then use -ge to compare:

if [ "${CPUusageCount%.*}" -ge $THRESHOLD_LIMIT ]
then
    # Send email
fi

Answer 2

You can use command-substitution to compare two floating-point number.

example:

CPUusageCount=99.99
THRESHOLD_LIMIT=55.55

if [ `python -c "print $CPUusageCount>$THRESHOLD_LIMIT"` == 'True' ]; then
    echo Sending mail to Support group
fi

Answer 3

您可以使用bc命令：

if [ $(echo "$CPUusageCount >= $THRESHOLD_LIMIT"|bc) -eq 1 ];

Answer 4

Floating point arithmetic is supported by ksh

#!/bin/ksh -x

CPUusageCount=99.99
THRESHOLD_LIMIT=55.55

if [ $CPUusageCount -gt $THRESHOLD_LIMIT ]; then
  echo Sending mail to Support group
fi

gives

+ CPUusageCount=99.99
+ THRESHOLD_LIMIT=55.55
+ [ 99.99 -gt 55.55 ]
+ echo Sending mail to Support group
Sending mail to Support group