How do I divide in the Linux console?

Question

I have to variables and I want to find the value of one divided by the other. What commands should I use to do this?

Is this really programming related? [http://stackoverflow.com/faq] — Frank V, Jul 06 '09 at 17:26
Check this article: [http://www.basicallytech.com/blog/index.php?/archives/23-command-line-calculations-using-bc.html](http://www.basicallytech.com/blog/index.php?/archives/23-command-line-calculations-using-bc.html) — freitass, Jul 06 '09 at 17:08
@frank-v Bash can be used for programming... also, that link to faq doesn't work — chomp, Jun 18 '16 at 01:52

score 74 · Answer 1 · answered Jul 06 '09 at 17:12

74

In the bash shell, surround arithmetic expressions with $(( ... ))

$ echo $(( 7 / 3 ))
2

Although I think you are limited to integers.

answered Jul 06 '09 at 17:12

dave4420

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10

Yes, bash is limited to integer math. – Matt K Jul 06 '09 at 18:17

score 43 · Answer 2 · answered May 21 '13 at 17:06

43

echo 5/2 | bc -l

2.50000000000000000000

this '-l' option in 'bc' allows floating results

answered May 21 '13 at 17:06

raytrace

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Cool; with `-l`, you get 20 decimal places by default *and* a math library is loaded that defines additional functions such as sine; to explicitly specify the number of decimal places, prepend the expression with `scale={numPlaces};` (too), as demonstrated in @user1504475's answer. In other words: `-l` is a convenient alternative to specifying `scale=20;`, but comes at a performance cost due to loading the library - the real-world impact appears to be negligible, though. – mklement0 Oct 27 '13 at 21:54

score 17 · Answer 3 · edited Apr 24 '13 at 15:12

17

Better way is to use "bc", an arbitrary precision calculator.

variable=$(echo "OPTIONS; OPERATIONS" | bc)

ex:

my_var=$(echo "scale=5; $temp_var/100 + $temp_var2" | bc)

where "scale=5" is accuracy.

man bc

comes with several usage examples.

edited Apr 24 '13 at 15:12

Pascail

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answered Jul 05 '12 at 15:27

user1504475

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Cool; one thing to note: not setting `scale` defaults to integer division - unless you specify `-l`, as @raytrace notes below, which apparently gives you 20 decimal places by default, but also loads a library with additional functions. – mklement0 Oct 27 '13 at 21:38

score 14 · Answer 4 · edited Jul 11 '14 at 20:57

14

You can use awk which is a utility/language designed for data extraction

e.g. for 1.2/3.4

>echo 1.2 3.4 | awk '{ print $2/$1 }'
0.352941

edited Jul 11 '14 at 20:57

dmportella

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answered Jul 11 '14 at 20:31

jperrie

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score 11 · Answer 5 · answered Jul 06 '09 at 18:51

11

I still prefer using dc, which is an RPN calculator, so quick session to divide 67 by 18 with 4 digits precision would look like

>dc
4k
67
18/p
3.7222
q
>

Obviously, much more available: man dc

answered Jul 06 '09 at 18:51

libjack

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A few pointers to possibly save some a trip to `man`: RPN = Reverse Polish Notation; in a nutshell: you enter the operands first, then the operator. A terminating `p` is needed to output the result. The non-interactive version of the above calculation is: `dc -e '4k 67 18 / p'`. Caveat: not setting the precision (with `{numPlaces}k`) defaults to 0, i.e., integer division. – mklement0 Oct 27 '13 at 21:39

score 10 · Answer 6 · edited Feb 25 '13 at 04:26

10

In bash, if you don't need decimals in your division, you can do:

>echo $((5+6))
11
>echo $((10/2))
5
>echo $((10/3))
3

edited Feb 25 '13 at 04:26

Levi Morrison

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answered Jul 06 '09 at 17:13

Mark Rushakoff

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score 5 · Answer 7 · answered Jul 06 '09 at 17:12

5

I assume that by Linux console you mean Bash.

If X and Y are your variables, $(($X / $Y)) returns what you ask for.

answered Jul 06 '09 at 17:12

Paolo Capriotti

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You don't need the $'s for the variables – Draemon Jul 06 '09 at 17:14

score 2 · Answer 8 · answered Jul 06 '09 at 17:13

2

Example of integer division using bash to divide $a by $b:

echo $((a/b))

answered Jul 06 '09 at 17:13

Draemon

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score 2 · Answer 9 · answered Feb 11 '14 at 22:23

Something else you could do using raytrace's answer. You could use the stdout of another shell call using backticks to then do some calculations. For instance I wanted to know the file size of the top 100 lines from a couple of files. The original size from wc -c is in bytes, I want to know kilobytes. Here's what I did:

echo `cat * | head -n 100 | wc -c` / 1024 | bc -l

score 1 · Answer 10 · edited Sep 08 '14 at 11:04

1

You should try to use:

echo "scale=4;$variablename/3"|bc

edited Sep 08 '14 at 11:04

fivedigit

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answered Sep 08 '14 at 10:20

JADAV AKASH

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score 1 · Answer 11 · answered May 08 '15 at 09:06

1

you can also use perl -e

perl -e 'print 67/8'

answered May 08 '15 at 09:06

lsiebert

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score -1 · Answer 12 · answered Nov 04 '17 at 19:53

-1

I also had the same problem. It's easy to divide integer numbers but decimal numbers are not that easy. if you have 2 numbers like 3.14 and 2.35 and divide the numbers then, the code will be Division=echo 3.14 / 2.35 | bc echo "$Division" the quotes are different. Don't be confused, it's situated just under the esc button on your keyboard. THE ONLY DIFFERENCE IS THE | bc and also here echo works as an operator for the arithmetic calculations in stead of printing. So, I had added echo "$Division" for printing the value. Let me know if it works for you. Thank you.

answered Nov 04 '17 at 19:53

SHIBLI

11
1

The quotes are not showing here, So, just put the quotes(``) after = and after bc. – SHIBLI Nov 04 '17 at 19:54
Those are not quotes. They are acute accents. They are not showing because StackOverflow uses them to highlight code snippets `some code here` was just wrapped in the acute accents. – Chris Sharp Nov 04 '17 at 20:27

How do I divide in the Linux console?

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