Fixed width to CSV

Question

I know how to use awk to change fixed width to CSV. What I have is a hard drive with a few thousand fixed width files. The all contain different column width fo

Answer 1

Using GNU awk for FIELDWIDTHS and \s/\S:

$ cat tst.awk
BEGIN { OFS="," }
FNR==1 { names=$0; next }
FNR==2 {
    FIELDWIDTHS=""
    while ( match($0,/\S+\s*/) ) {
        FIELDWIDTHS = (FIELDWIDTHS ? FIELDWIDTHS " " : "") RLENGTH
        $0 = substr($0,RSTART+RLENGTH)
    }
    $0 = names
}
{
    for (i=1;i<=NF;i++) {
        sub(/\s+$/,"",$i)
        printf "%s%s", $i, (i<NF?OFS:ORS)
    }
}

$ awk -f tst.awk file
Name,DOB,GENDER
JOHN DOE,19870130,M
MARY DOE,19850521,F
MARTY MCFLY,19790320,M

The above will work even if your first row contains spaces in the column names.