Shell Programming and Scripting

I am using bash
I have a script that takes a number, i.e. 85.152, which is always a non integer and essentially tries to get that number to be a multiple of 10. My code is as follows:

Code:

number=85.152
A=${number%.*} #Converts float to integer
typeset -i B=$(((A-20)/10)) #subtracting 20 is desired, dividing by 10 is done to get the value less than 10 (only works for numbers less than 100)
typeset -i C=${B%.*} #converts float to integer (redundant I know, but necessary)
typeset -i answer=$((C * 10)) #Gives me a multiple of 10

Explanation:
1. I convert from a float to integer first because I cannot simply divide 85.152 by 10 using bash. It does not like dividing floats.
2. I subtract 20 because this is desired by design (it can be ignored). The division by 10 gets me to a number below 10 which is just a trick because any integer less than 10 which is multiplied by 10 will simply be a multiple of 10.
3. I convert from float to integer again just in case the number I divided, (to get less than 10), ends up dividing out to be another float (i.e. 85/10=8.5, then truncate to 8).
4. Finally I multiply by 10, 8*10=80 which is a multiple of 10.


I did what I could as a newbie to make it work but now I would like to simplify this process. I simply want to take 85.152 and make it a multiple of 10 that is 20 less than 85.152. So answer = (85.125-20) truncated to a multiple of 10. Should be 60. Any suggestions?

Not sure what you mean. Something like this maybe?

Code:

answer=$(((${number%.*}-20)/10*10))

or

Code:

answer=$(((${number%.*}/10-2)*10))

Code:

$ V=85.5
$ echo $(( ${V%.*}-(${V%.*}%10)-20 ))

60

$

OSX 10.7.5, default bash terminal...
How about:-

Code:

Last login: Sat Oct 24 08:38:01 on ttys000
AMIGA:barrywalker~> x=87.1173
AMIGA:barrywalker~> y=20
AMIGA:barrywalker~> echo $[${x%.*}-${x%.*}%10-$y]
60
AMIGA:barrywalker~> _

Code:

x=85.152
y=20
$ echo "(($x-$y)/10)*10"|bc 
60

How about

Code:

number=85.152
echo $((${number%?.*}0 - 20 ))
60
number=895.152
echo $((${number%?.*}0 - 20 ))
870

Hi RudiC...
Neat!
Contracting on your method, OSX 10.7.5, default bash terminal:-

Code:

Last login: Sat Oct 24 17:08:09 on ttys000
AMIGA:barrywalker~> number=87.11234
AMIGA:barrywalker~> echo $[${number%?.*}0-20]
60
AMIGA:barrywalker~> number=897.1357
AMIGA:barrywalker~> echo $[${number%?.*}0-20]
870
AMIGA:barrywalker~> _

EDIT:-
Important note both methods do not work with the number 80 but do if converted to 80.0 float equivalent.