csv-flex example

$ uname -a
FreeBSD BanjaLuka 12.0-RELEASE-p3 FreeBSD 12.0-RELEASE-p3 GENERIC  amd64

$ cat cvs2t.l
%%

"'"[^']*"'"     ECHO;
,               putchar('\t');
.               ECHO;

$ flex cvs2t.l

$ cc lex.yy.c -ll -o cvs2t

$ cat cvs.dat
red,white,blue
'red,white,blue','red,green,black','gray,orange,yellow'

$ cvs2t < cvs.dat
red     white   blue
'red,white,blue'        'red,green,black'       'gray,orange,yellow'

$