divide in bash to 1 decimal place

[w5000]

hello,

on a system having no bc, perl, awk, and to which I have no administrator rights (only common user account), with restricted shell (bash), sed and expr available, I need to be able divide numbers to 1 decimal place:

> echo $((10/10))
1
> echo $((5/10))
0

I'd like to get 1.0, 0.1, etc (so leading zero for <1)

also builtin let gives 0
> let "m=1/4";echo $m
0

thanks in advance for a hint!

 

[ChrisHirst]

bash doesn't have floating point maths built in, so without 'bc' and it's associated scale=n, decimal places simply are not going to happen.

try expr 4 / 3 and see what the result is.



Chris.

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[w5000]

so it looks there is no local solution on this host...

> expr 4 / 3
1

> expr 1 / 3
0

 

[feherke]

Hi

If you want to keep your script pure Bash, you can do a trick by multiplying the dividend enough so integer arithmetics give precise enough result, then add separate the fractional part with string operation :

[navy]m[/navy][teal]=[/teal][navy]$(([/navy] [COLOR=#993399]4[/color] [teal]*[/teal] [COLOR=#993399]10[/color] [teal]/[/teal] [COLOR=#993399]3[/color] [navy]))[/navy]
echo [i][green]"${m:0:-1}.${m: -1}"[/green][/i]

But better use tool instead. Either the already mentioned Bc with its verbose syntax, or Dc :

[blue]master #[/blue] bc <<< 'scale=1;4/3'
1.3

[blue]master #[/blue] dc <<< '1k4 3/p'
1.3

Feherke.
feherke.ga

 

[stefanhei]

If it's for scale 1 why not simply multiply the numerator by 10 and use string manipuation to insert the point.
Maybe something like this (rough draft):

#!/bin/bash

X=3
Y=4

X10=$(($X*10))

R=$(($X10/$Y))
[ $(($X/$Y)) -ge 1 ] && RD=${R:0:${#R}-1}.${R:${#R}-1} || RD=0.$R

echo $RD

Just keep in mind that your result is a string...