header does not respect FS flag in BEGIN

[brentp]

this will demonstrate the problem:

Given his text file

echo $'a space\tb\n1\t2\n1\t2' > t.txt

and this code:

./awk 'BEGIN{FS="\t"}{ print $b }' t.txt

I expect:

b
2
2

but it instead gives nothing because it splits the headers on space sets them as are a, space,b
even though the separator is '\t'. This is because the headers are parsed before the BEGIN block
sets FS.

[ghuls]

Though, even if it was parsed correctly, it would give problems, because you can't use variables with a space AFAIK.
So you could only use it for the non-space containing header fields.

A possible solution would be to replace the space in a header field with a "_" automatically:

printf 'a space\tb\n1\t2\n1\t2\n' | ./bioawk -c hdr 'BEGIN { FS=OFS="\t" } { print $a_space, $b }'