sleep command and figure percentage in a script

[squash]

Hello a couple of quick and hopefully simple questions.

1. Is there any way to use the sleep command for less than one second time interval? i.e.
while :
do
echo “1”
sleep .5
done
2. What might be an easy way to figure out a percentage in a script.
For example I know how to capture a number for a specific count and this will rise and fall all day, I am only concerned if it jumps by say 20%.

So an example might be

MQ=`netstat –n |grep 59100|wc –l
A=`cat fileone`
B=`cat filetwo`

while :
do
$MQ >fileone
sleep 600
$MQ>filetwo

# Ok this is where I am guessing.

let C=$B-$A
let D=$C/$A

if [ $D –gt 20 ]
then
beep me
else
sleep 3600
fi
done

As Alway we thank you for your support.

 

[vgersh99]

echo "scale=2; ((${B} - ${A}) / ${B}) * 100" | bc vlad
+----------------------------+
| #include<disclaimer.h> |
+----------------------------+

 

[squash]

Ok,
It took some playing with my variables, but I got it to work just fine.

So arithmatic functions just happen I guess?
Or I guess a better questions is can you break down what is happening for me.

What is scale?

Thankx for you help all the same

 

[vgersh99]

you need floating number operation to calculate percentage.
Shells [mostly] don't support that. Therefore you need to use 'bc'.

From 'man bc':
scale ( E )
Number of digits right of decimal point.


By default scale=0 which makes all operations interger.
The rest of the expression is the percentage calculation given your formula from the original post [if I understood it correctly].
vlad
+----------------------------+
| #include<disclaimer.h> |
+----------------------------+

 

[squash]

right on I get that, and yes you did understand my orig post correctly.

I guess I just have not seen the use of the echo command as in your statement.

Althought it works great.

Thankx again