Hello,
When using bioawk with the -c fastx option the OFS parameter is set to a tab (\t) with no way to change it.
Reproduced by building from source.
Test:
bioawk -c fastx -v OFS=" " '{print OFS}' some.fasta | head -1 | od -bc
Will output:
0000000 011 012
\t \n
0000002
Note: some.fasta can be anything (if at least it is a fasta file), but not providing any file will not trigger this.