Re: [Bug-apl] debugging a cgi script

[Juergen Sauermann]

Hi Alex,

you could use ⎕FIO to write information about how far you came in the 
script into a separate
file for debugging purposes.

I haven't seen your code, but from the error text I would assume that 
either you haven't provided,
the CGI header, or the DOMAIN ERROR occurred before the CGI header was 
printed.

Have a look at the HTML workspace (provided with GNU APL) which does it 
like this:

*⍝⍝⍝⍝⍝⍝⍝⍝⍝⍝⍝⍝⍝⍝⍝⍝⍝⍝⍝⍝⍝⍝⍝⍝⍝⍝⍝⍝⍝⍝⍝⍝⍝⍝⍝⍝⍝⍝⍝⍝⍝**
**⍝ emit a CGI header (if started from a web server)**
**∇xZ←HTML∆HTTP_header**
** xZ←'' ◊ →(0=⍴,⎕ENV "GATEWAY_INTERFACE")⍴0   ⍝ nothing if not run as 
CGI script**
** ⍝**
** ⍝ The 'Content-type: ...' string ends with LF (and no CR)**
** ⍝ ⎕UCS 13 10 13 emits CR LF CR.**
** ⍝ Together this gives two lines, each ending with CR/LF**
** ⍝ Most tolerate LF without CR, but the CGI standard wants CR/LF**
** ⍝**
** xZ←'Content-type: text/html; charset=UTF-8', ⎕UCS 13 10 13**
**∇**
*
As soon as the CGI header is correct every output shows up in the web 
page and therefore there
is no need for extra debugging capabilities. Make sure thak nothing else 
is printed before the CGI header!

/// Jürgen



On 08/14/2016 03:27 AM, Alex Weiner wrote:
> Hi Bug APL,
> I am having difficulty pinning down this error that occurs when 
> executing my script from a webserver (as a CGI script). The error does 
> not occur when I mock up data to bypass values filled in by ⎕env, and 
> run the script locally. I'm using apache, and the error logs are 
> terribly opaque:
> (removing personal info)
>
>     malformed header from script 'runflake': Bad header: DOMAIN ERROR
>
> Would it be possible to have the function and line number included in 
> this?
> I'm also fairly new at CGI scripting, so if anyone can direct me to 
> alternate debugging methods, that would work too.
>
> Best,
> Alex