Rounding in a bash script

[rossoreed]

I'm writing a bash script which provides data about the SD card, and I've run into this issue. (sorry if it's a basic mistake)

If I run;

Code: Select all

$sudo blockdev --getsz /dev/mmcblk0

I get the correct answer - 15130624

But if I combine it with some calculations;

Code: Select all

DISK_SIZE="$(($(sudo blockdev --getsz /dev/mmcblk0)/2048/925))"

I get 7, instead of 7.987027027027

[allfox]

I think you need a calculator program to help.

Get "calc" command from the apcalc package: sudo apt install apcalc

Code: Select all

#! /bin/bash

CALC="/usr/bin/calc -p"

echo `$CALC "1 / 4"`

exit 0

[Paeryn]

Bash only deals with integer numbers. As allfox said, you need to use other programs if you want floating point numbers.

[PeterO]

This should be in your book marks list http://www.tldp.org/LDP/abs/html/index.html
abs = Advanced Bash-Scripting Guide

For maths see http://www.tldp.org/LDP/abs/html/arithexp.html

PeterO

[rossoreed]

OK thanks, I'll look at plan B!

Paul