How to loop through a range of decimal numbers in bash?

Question

I'd like to generate a sequence of equally spaced decimal numbers.

For example, I want to echo all numbers between 3.0 and 4.5, with step 0.1. I tried $ for i {3.0..4.5..0.1}; do echo $i; done, but this gives an error.

I also tried $ for i in $(seq 3.0 4.5 0.1); do echo $i; done but nothing happens.

Tangram

Bash doesn't do floating point numbers. You're best off switching to a different scripting language. – Arabic

Is there a command to replace seq that can generate that list so I can use it? – Tangram

Answer 1

I also tried $ for i in $(seq 3.0 4.5 0.1); do echo $i; done but nothing happens.

The order is wrong:

$ for i in $(seq 3.0 0.1 4.5); do echo $i; done

Hyperthyroidism

Wow, thanks this works great. Much easier to read than the other methods. – Tangram

Answer 2

If you're looking for a loop from 3.5 to 4.5 in 0.1 steps this would work

for x in {35..45}; do
     y=`bc <<< "scale=1; $x/10"`
     echo $y
done

The same with 0.01 steps

for x in {350..450}; do
         y=`bc <<< "scale=2; $x/100"`
         echo $y
done

Patronizing

Thanks, this works. Is bc compulsory for the division? – Tangram

Just googled it, now I'm using for x in {30..45}; do y=$(dc <<< "1k $x 10/p"); echo $y; done. – Tangram

Yeah, either one works. bash only support integer arithmetic. Therefore, one always needs to use another program... – Patronizing

Answer 3

 for i in {3.0,4.5,0.1}; do echo $i; done

Went

No, that only prints three lines 3.0, 4.5 and 0.1. – Tangram

What do you want to print ?? – Went

A range of decimal numbers, e.g. 3.0 3.1 3.2 3.3 ... 4.5 – Tangram

@Tangram - The original question was prone to misunderstandings. The syntax shown here is useful for what it was meant to. – Demoiselle

What this syntax is "meant to do", however, has no reasonable relationship with "loop[ing] through a range of decimal numbers". – Harold