Question

I would like to write a bash script in Linux that executes a program multiple times (e.g., 3 times) and that specifies a switch value based on a list of values provided in a text file.

For example, suppose that there is some program programname that has a switch -switch that takes a floating point number as input. So, one execution of the program might read:

programname -switch 0.05

where 0.05 is a particular value passed to the switch -switch.

Now I would like to read in some sort of text file that has a list of values that I would like to pass, in succession, to -switch in separate calls of programname. My text file test.txt might contain these data:

0.05
3.19
100.75

I would like to write a bash script that will read in the text file and effectively make these calls in succession:

programname -switch 0.05
programname -switch 3.19
programname -switch 100.75

I am thinking of something like this:

#!/bin/bash
for i in {1..3}
do
programname -switch $x
done

But, what should I type in place of $x? In other words, I am not sure how to read in test.txt and provide its contents, one-by-one, to -switch as the for loop runs. Do you have any advice? Thank you!

Answer 1

values.txt:

0.05
3.19
100.75

script.sh:

#!/bin/bash

counter=1
for value in $(cat values.txt)
do
    programname -switch $value -counter $counter
    counter=$(expr $counter + 1)
done