Tail a logfile to a web page

**Benjamin Niemann** · Jul 24 '05, 12:43 AM

Re: Tail a logfile to a web page

Dan Olson wrote:
[color=blue]
> I want to be able to view log files on web page and want to know what
> the options are for dynamically updating the log output without
> having to refresh the page. Basically have it behave like
> "tail -f some.log".
>
> I tried a java applet to display the log output from a TCP stream and
> it works nicely, but then I discovered that the latest MS browers
> don't come with java support and I prefer to do this without making
> the user install any extra plugins. Hmmm.
>
> Any ideas?[/color]

You could output the lines from the log file as they come in to the browser,
flushing the stream after every line (without closing the connection). A
browser that displays the page incrementially, should reproduce the desired
behaviour.

But this is a server side issue - not related to HTML. You should ask in a
group about CGI or PHP for more details.

--
Benjamin Niemann
Email: pink at odahoda dot de
WWW: http://www.odahoda.de/

**David Ross** · Jul 24 '05, 12:43 AM

Re: Tail a logfile to a web page

Dan Olson wrote:[color=blue]
>
> I want to be able to view log files on web page and want to know what
> the options are for dynamically updating the log output without
> having to refresh the page. Basically have it behave like
> "tail -f some.log".
>
> I tried a java applet to display the log output from a TCP stream and
> it works nicely, but then I discovered that the latest MS browers
> don't come with java support and I prefer to do this without making
> the user install any extra plugins. Hmmm.[/color]

I assume you are creating the Web page's HTML dynamically from the
log file via some kind of script operating outside the Web page.

In the HEAD section of the generated HTML file, include the
following line:
<meta http-equiv="Refresh" content="nn">
where nn is some integer. The page will refresh every nn seconds.

See <URL:http://cad.chp.ca.gov/>. The middle frame has nn=30.

--

David E. Ross
<URL:http://www.rossde.com/>

I use Mozilla as my Web browser because I want a browser that
complies with Web standards. See <URL:http://www.mozilla.org/>.

**Dan Olson** · Jul 24 '05, 12:43 AM

Re: Tail a logfile to a web page

David Ross <nobody@nowhere .not> writes:
[color=blue]
> I assume you are creating the Web page's HTML dynamically from the
> log file via some kind of script operating outside the Web page.[/color]

Yes. Basically I'm going down the path of using a web based interface
embedded in a network device for setup and monitoring. As opposed to
the good old RS232 or telnet console interface. Anyway, I'm more of
an embedded software developer so am not familiar with all the
different techniques usable with a web browser. A HTML interface
seemed nice in that the end user doesn't need to install any software
on their computer to configure and monitor the device I'm working on.
[color=blue]
> In the HEAD section of the generated HTML file, include the
> following line:
> <meta http-equiv="Refresh" content="nn">
> where nn is some integer. The page will refresh every nn seconds.
>
> See <URL:http://cad.chp.ca.gov/>. The middle frame has nn=30.[/color]

This sounds like it will work for what I want to do. I'll see if I
can figure out how to use the refresh tag when the browser doesn't
support Java.

--
dano

**David Ross** · Jul 24 '05, 12:43 AM

Re: Tail a logfile to a web page

Dan Olson wrote:[color=blue]
>
> David Ross <nobody@nowhere .not> writes:
>[color=green]
> > I assume you are creating the Web page's HTML dynamically from the
> > log file via some kind of script operating outside the Web page.[/color]
>
> Yes. Basically I'm going down the path of using a web based interface
> embedded in a network device for setup and monitoring. As opposed to
> the good old RS232 or telnet console interface. Anyway, I'm more of
> an embedded software developer so am not familiar with all the
> different techniques usable with a web browser. A HTML interface
> seemed nice in that the end user doesn't need to install any software
> on their computer to configure and monitor the device I'm working on.
>[color=green]
> > In the HEAD section of the generated HTML file, include the
> > following line:
> > <meta http-equiv="Refresh" content="nn">
> > where nn is some integer. The page will refresh every nn seconds.
> >
> > See <URL:http://cad.chp.ca.gov/>. The middle frame has nn=30.[/color]
>
> This sounds like it will work for what I want to do. I'll see if I
> can figure out how to use the refresh tag when the browser doesn't
> support Java.[/color]

REFRESH is not a tag. It's a value for a META tag, which in turn
is a substitute for a field on the HTML tag.

This does not require Java. However, not all browsers support
REFRESH. I know that Mozlla and Firefox support it, and I think IE
supports it. If you're not sure about your browser, test it with
my <URL:http://www.rossde.com/get_index.html> . If you get my Index
without selecting the "Go" button, your browser supports REFRESH.

--

David E. Ross
<URL:http://www.rossde.com/>

I use Mozilla as my Web browser because I want a browser that
complies with Web standards. See <URL:http://www.mozilla.org/>.

**Dan Olson** · Jul 24 '05, 12:43 AM

Re: Tail a logfile to a web page

David Ross <nobody@nowhere .not> writes:
[color=blue]
> Dan Olson wrote:[color=green]
> > This sounds like it will work for what I want to do. I'll see if I
> > can figure out how to use the refresh tag when the browser doesn't
> > support Java.[/color]
>
> REFRESH is not a tag. It's a value for a META tag, which in turn
> is a substitute for a field on the HTML tag.
>
> This does not require Java. However, not all browsers support
> REFRESH. I know that Mozlla and Firefox support it, and I think IE
> supports it. If you're not sure about your browser, test it with
> my <URL:http://www.rossde.com/get_index.html> . If you get my Index
> without selecting the "Go" button, your browser supports REFRESH.[/color]

Oh, what my last statement above meant is I want to use a Java applet
when the user's browser supports it because it will show log messages
as they arrive. But I would have an alternate page that uses the
refresh value when the browser does not support Java. Sorry for the
confusion. Also, I expect all my users to be running either a IE or a
Mozilla derivative so I think your technique will work great.

--
dano

**Chris Morris** · Jul 24 '05, 12:43 AM

Re: Tail a logfile to a web page

David Ross <nobody@nowhere .not> writes:[color=blue]
> Dan Olson wrote:[color=green]
> > This sounds like it will work for what I want to do. I'll see if I
> > can figure out how to use the refresh tag when the browser doesn't
> > support Java.[/color]
>
> REFRESH is not a tag. It's a value for a META tag, which in turn
> is a substitute for a field on the HTML tag.[/color]

Wrong. It's a substitute for a HTTP header. (Except that there isn't a
HTTP header "Refresh" in the specification)
[color=blue]
> This does not require Java. However, not all browsers support
> REFRESH. I know that Mozlla and Firefox support it, and I think IE
> supports it. If you're not sure about your browser, test it with
> my <URL:http://www.rossde.com/get_index.html> . If you get my Index
> without selecting the "Go" button, your browser supports REFRESH.[/color]

IE *sometimes* supports it. It can be enabled or disabled through the
security zone settings.

--
Chris

**Richard Gration** · Jul 24 '05, 12:43 AM

Re: Tail a logfile to a web page

On Mon, 11 Jul 2005 10:48:54 -0700, David Ross wrote:[color=blue]
> REFRESH is not a tag. It's a value for a META tag, which in turn
> is a substitute for a field on the HTML tag.[/color]

A small point, but ...

REFRESH (or "Refresh:") is a HTTP header. The META tag is a way to allow
pages to specify values for some HTTP headers.

Rich

**Alan J. Flavell** · Jul 24 '05, 12:43 AM

Re: Tail a logfile to a web page

On Tue, 12 Jul 2005, Richard Gration wrote:
[color=blue]
> REFRESH (or "Refresh:") is a HTTP header.[/color]

Well, only in as much as the applicable HTTP RFC (2616) allows
arbitrary HTTP headers to be added, even though they're not defined in
the RFC.

Last time I tested, IE doesn't support this HTTP "header". It only
supports the substitute meta. Quaint, really.
[color=blue]
> The META tag is a way to allow pages to specify values for some HTTP
> headers.[/color]

I'm afraid that's very misleading. I know of very few web servers
which parse HTML and turn the resulting meta items into real HTTP
headers. And in this case it's far from clear that it would really do
anything constructive.

OK, I admit that *was* originally the intention of meta, but it seems
to have quickly dropped out of the plan, many years ago now. If you
want a server to produce HTTP headers, I'd have to recommend reading
its instructions to find out how to ask it to produce real HTTP
headers (Apache has a number of versatile options for this).

I might add that HTTP headers are something that make good sense with
all kinds of content, such as images, PDF files, plain text, etc.
etc., and are by no means limited to HTML, whereas meta is defined
only for (x)html.

Nowadays, if anything is going to pay attention to meta in HTML, it's
likely to be the client agent. But meantime the other participants in
the web transaction (proxies, web caches etc.) will typically be
disregarding the meta inside the HTML, and honouring only the real
HTTP headers, which can produce a really confusing mess for anyone who
seriously thinks that sticking in a meta is any real substitute for a
real HTTP header.

no offence intended.

**Randal L. Schwartz** · Jul 24 '05, 12:43 AM

Re: Tail a logfile to a web page

*** post for FREE via your newsreader at post.newsfeed.c om ***
[color=blue][color=green][color=darkred]
>>>>> "Dan" == Dan Olson <danole@comcast .net> writes:[/color][/color][/color]

Dan> I want to be able to view log files on web page and want to know what
Dan> the options are for dynamically updating the log output without
Dan> having to refresh the page. Basically have it behave like
Dan> "tail -f some.log".

Been there. Done that.

<http://www.stonehenge. com/merlyn/PerlJournal/col01.html>

--
Randal L. Schwartz - Stonehenge Consulting Services, Inc. - +1 503 777 0095
<merlyn@stonehe nge.com> <URL:http://www.stonehenge. com/merlyn/>
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**Richard Gration** · Jul 24 '05, 12:44 AM

Re: Tail a logfile to a web page

On Tue, 12 Jul 2005 17:43:55 +0100, Alan J. Flavell wrote:[color=blue]
>
> no offence intended.[/color]

None taken. I almost always get corrected on Usenet. Some of it has
actually sunk in ... ;-)

rich

Tail a logfile to a web page

Tail a logfile to a web page

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