Bash, csv file: get number of rows by column name - bash

Question

What I have:
file.csv
car, speed, gas, color
2cv, 120, 8 , green
vw, 80, , yellow
Jaguar, 250, 15 , red
Benz, , , silver
What I have found:
This script returns exactly what I need by column number:
#!/bin/bash
awk -F', *' -v col=3 '
FNR>1 {
if ($col)
maxc=FNR
}
END {
print maxc
}
' file.csv
read -p "For End press Enter or Ctl + C"
I get exactly the output which I need (the number of the last line of column):
* for "col=1" ("car" column), the answer: 5
* for "col=2" ("speed" column), the answer: 4
* for "col=3" ("gas" column), the answer: 4
* for "col=4" ("color" column), the answer: 5
What I am looking for:
I am looking for a way to get the same not by "vol=volumnumber p.e. vol=3" but by "vol=columnheadlinevalue p.e. vol=gas".
It can be, it need additional like:
col_name=gas # selected column headline
col=get column number from $col_name # not working part

Answer 1

Here's one way to do exactly what you do but which finds the column name when FNR==1:
#!/bin/bash
columns=(car speed gas color)
for col in "${columns[#]}"
do
LINE_CNT=$(awk '-F[\t ]*,[\t ]*' -vcol=${col} '
FNR==1 {
for(i=1; i<=NF; ++i) {
if($i == col) {
col = i;
break;
}
}
if(i>NF) {
exit 1;
}
}
FNR>1 {
if($col) maxc=FNR;
}
END{
print maxc;
}' file.csv)
echo "$col $LINE_CNT"
done
Output:
car 5
speed 4
gas 4
color 5