I've created a perl script c.pl
print "Content-type: image/gif\n\n";
...
and
...
exit 200;
output is :
Content-type: image/gif GIF89an
... this is wrong. it seems to generate output of Content-type: text/html prior...
how can I make it output as image/gif header?
The default Content-type
HTTTP header is text/html
. But you can (and here should) change it - either by using CGI variables or by writting your HTTP headers from your script.
G-WAN comes with many examples doing that, see fractal.c.