Format a bash command in a script

Question

in the shell i type:

bc -l <<< '90.8/(179*179)*10000'

and i get the correct output:

28.33869105208951030000

however i am not able to format this correct in a bash script:

calculate_bmi () {
    BMI="$(bc -l <<< '${1}/(${2}*${2})*10000)'"
    echo "${BMI}"
}

I get all kind of strange errors when i tried different experiments. Latest error is:

./wts.sh: command substitution: line 25: syntax error near unexpected token `('
./wts.sh: command substitution: line 25: `bc -l <<< ${1}/(${2}*${2})*10000)"'

Please help me.

You don't need the variable; just let the output of bc go to standard output instead of capturing it. calculate_bmi () { bc -l <<< "$1/($2*$2)*10000"; }. — chepner
– chepner, Commented Jan 11, 2018 at 13:21
The echo statement was only for debugging purposes, i think i need a variable since i am writing the value to a csv file together with other data. Anyway, it works as it should at the moment. — macbug
– macbug, Commented Jan 11, 2018 at 13:23

arco444 · Accepted Answer · 2018-01-11 09:38:54Z

2

Write your function as below:

calculate_bmi () {
    BMI=$(bc -l <<< "${1}/(${2}*${2})*10000")
    echo "${BMI}"
}

You must use double quotes (rather than single) in order to interpolate the variables.

answered Jan 11, 2018 at 9:38

arco444

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