[6483] in Perl-Users-Digest
Perl-Users Digest, Issue: 109 Volume: 8
daemon@ATHENA.MIT.EDU (Perl-Users Digest)
Thu Mar 13 11:17:16 1997
Date: Thu, 13 Mar 97 08:01:47 -0800
From: Perl-Users Digest <Perl-Users-Request@ruby.OCE.ORST.EDU>
To: Perl-Users@ruby.OCE.ORST.EDU (Perl-Users Digest)
Perl-Users Digest Thu, 13 Mar 1997 Volume: 8 Number: 109
Today's topics:
Reading from serial port within perl ? (Avi)
Re: Reading from serial port within perl ? <tchrist@mox.perl.com>
redirection: Document Moved (Eddie Babin)
Re: redirection: Document Moved (Chris Nandor)
Socket reading problem. Help, please <shu@iis.nsk.su>
Re: We've baffled tech support, now on to Usenet... <tchrist@mox.perl.com>
Re: We've baffled tech support, now on to Usenet... (Ronald L. Parker)
Re: weird digit regexp behaviour (Honza Pazdziora)
Re: weird digit regexp behaviour <tchrist@mox.perl.com>
What language do Perl REs recognize? (Bernie Cosell)
Re: Who makes more $$ - Windows vs. Unix programmers? <wang_ling@jpmorgan.com>
Win32::ODBC - how to get it working in CGI scripts? <andrzejt@free.polbox.pl>
Digest Administrivia (Last modified: 8 Mar 97) (Perl-Users-Digest Admin)
----------------------------------------------------------------------
Date: Thu, 13 Mar 1997 13:51:33 GMT
From: avi@tase.co.il (Avi)
Subject: Reading from serial port within perl ?
Message-Id: <33280521.1918488@news.ibm.net.il>
Hello !
As a novice I believe that there is a simple way for reading a serial
port from a perl program.
I wonder if someone have a simple example for reading a record from
the serial port and writing ot to a file ?
Thank you !
Avi
I'll appriciate if you can cc your message via e-mail as well to:
avi@tase.co.il Thank's again !
------------------------------
Date: 13 Mar 1997 15:00:56 GMT
From: Tom Christiansen <tchrist@mox.perl.com>
Subject: Re: Reading from serial port within perl ?
Message-Id: <5g94r8$c57$3@csnews.cs.colorado.edu>
[courtesy cc of this posting sent to cited author via email]
In comp.lang.perl.misc,
avi@tase.co.il (Avi) writes:
:Hello !
:
:
:As a novice I believe that there is a simple way for reading a serial
:port from a perl program.
:
:I wonder if someone have a simple example for reading a record from
:the serial port and writing ot to a file ?
:
:Thank you !
UBFAQQED -- from section 8.
How do I read and write the serial port?
This depends on which operating system your program is running
on. In the case of Unix, the serial ports will be accessible through
files in /dev; on other systems, the devices names will doubtless
differ. Several problem areas common to all device interaction are
the following
lockfiles
Your system may use lockfiles to control multiple access. Make
sure you follow the correct protocol. Unpredictable behaviour
can result from multiple processes reading from one device.
open mode
If you expect to use both read and write operations on the
device, you'll have to open it for update (see the section on
"open" in the perlfunc manpage for details). You may wish to
open it without running the risk of blocking by using sysopen()
and `O_RDWR|O_NDELAY|O_NOCTTY' from the Fcntl module (part of
the standard perl distribution). See the section on "sysopen"
in the perlfunc manpage for more on this approach.
end of line
Some devices will be expecting a "\r" at the end of each line
rather than a "\n". In some ports of perl, "\r" and "\n" are
different from their usual (Unix) ASCII values of "\012" and
"\015". You may have to give the numeric values you want directly,
using octal ("\015"), hex ("0x0D"), or as a control-character
specification ("\cM").
print DEV "atv1\012"; # wrong, for some devices
print DEV "atv1\015"; # right, for some devices
Even though with normal text files, a "\n" will do the trick,
there is still no unified scheme for terminating a line that
is portable between Unix, DOS/Win, and Macintosh, except to
terminate *ALL* line ends with "\015\012", and strip what you
don't need from the output. This applies especially to socket
I/O and autoflushing, discussed next.
flushing output
If you expect characters to get to your device when you print()
them, you'll want to autoflush that filehandle, as in the older
use FileHandle;
DEV->autoflush(1);
and the newer
use IO::Handle;
DEV->autoflush(1);
You can use select() and the `$|' variable to control autoflushing
(see the section on "$|" in the perlvar manpage and the "select"
entry in the perlfunc manpage):
$oldh = select(DEV);
$| = 1;
select($oldh);
You'll also see code that does this without a temporary variable, as in
select((select(DEV), $| = 1)[0]);
As mentioned in the previous item, this still doesn't work when
using socket I/O between Unix and Macintosh. You'll need to
hardcode your line terminators, in that case.
non-blocking input
If you are doing a blocking read() or sysread(), you'll have to
arrange for an alarm handler to provide a timeout (see the "alarm"
entry in the perlfunc manpage). If you have a non-blocking open,
you'll likely have a non-blocking read, which means you may have
to use a 4-arg select() to determine whether I/O is ready on
that device (see the section on "select" in the perlfunc manpage.
--tom
--
Tom Christiansen tchrist@jhereg.perl.com
You are unlucky enough to bump into all my rough edges. --Andrew Hume
------------------------------
Date: 13 Mar 1997 13:31:55 GMT
From: ebabin@cyberenet.net (Eddie Babin)
Subject: redirection: Document Moved
Message-Id: <5g8vkb$2rk@news.cyberenet.net>
Sorry to repeat this question since I've seen the answer somewhere
but can't find it now...
Trying to redirect to another location but the server displays a
page stating Document Moved and a link to the actual document.
How do I skip that intermediate page?
#!/usr/local/bin/perl -w
$postinput = <STDIN>;
($junk, $userid) = split( /=/, $postinput);
print "Content-type: text/html\n";
print "Status: 302 Redirect \n";
print "Location: http://www.mysite.com:80/clients/", $userid, "/test.html\n";
--
------------------------------
Date: Thu, 13 Mar 1997 09:46:34 -0500
From: pudge@pobox.com (Chris Nandor)
Subject: Re: redirection: Document Moved
Message-Id: <pudge-ya02408000R1303970946340001@news.idt.net>
In article <5g8vkb$2rk@news.cyberenet.net>, ebabin@cyberenet.net (Eddie
Babin) wrote:
#Sorry to repeat this question since I've seen the answer somewhere
#but can't find it now...
#
#Trying to redirect to another location but the server displays a
#page stating Document Moved and a link to the actual document.
#How do I skip that intermediate page?
Not a perl question. Try comp.infosystems.www.authoring.cgi.
#================================================================
If you define cowardice as running away at the first sign of
danger, screaming and tripping and begging for mercy, then yes,
Mister Brave Man, I guess I am a coward.
--Jack Handey
Chris Nandor pudge@pobox.com
PGP Key 1024/B76E72AD http://pudge.net/
Keyfingerprint = 08 24 09 0B CE 73 CA 10 1F F7 7F 13 81 80 B6 B6
------------------------------
Date: Thu, 13 Mar 1997 20:49:15 +0600
From: Alexander Osipov <shu@iis.nsk.su>
Subject: Socket reading problem. Help, please
Message-Id: <332813EB.4431@iis.nsk.su>
Hello,
Does this program work???
For me it prints "Connected" and doesn't read something from socket.
As I think it should read 'login: ' at least.
What's wrong?
#!/usr/local/bin/perl
use
Socket;
my ($remote,$port, $iaddr, $paddr, $proto, $line);
$remote = "java";
$port = 9999; # telnet port
$iaddr = inet_aton($remote) || die "no host: $remote";
$paddr = sockaddr_in($port, $iaddr);
$proto = getprotobyname('tcp');
socket(SOCK, PF_INET, SOCK_STREAM, $proto) || die "socket: $!";
connect(SOCK, $paddr) || die "connect: $!";
print "Connected\n";
$line = <SOCK>; # HANGS HERE. WHY?
print "Line = $line\n";
close (SOCK) || die "close: $!";
--
Best regards,
Alexander Osipov
------------------------------
Date: 13 Mar 1997 14:35:05 GMT
From: Tom Christiansen <tchrist@mox.perl.com>
Subject: Re: We've baffled tech support, now on to Usenet...
Message-Id: <5g93ap$ai9$1@csnews.cs.colorado.edu>
[courtesy cc of this posting sent to cited author via email, but
only because i deleted NOSPAM from his fricking address, which is
just what the spam people will do, which means all he does is
stop people from trying to help him.]
In comp.lang.perl.misc,
"Jason Maggard" <jman95@ix.NOSPAMnetcom.com> writes:
: This program is a really simple thing, but I cannot get it to run on my
:web server. I use netcom, and all other scripts run fine. Any input???? I
:spent 2 hours with the Netcom hosting support kids, and they just finally
:gave up with a resounding "Hmph, I dunno..."
You have at least 2 fatal errors involving the wrong case
and several dangerous but not immediately fatal coding errors
involving return values.
I'm not going to tell you what they are because you're recreating
the wheel, which is really sad to see, and I will not encourage it.
>From the FAQ:
=head2 How do I decode a CGI form?
A lot of people are tempted to code this up themselves, so you've
probably all seen a lot of code involving C<$ENV{CONTENT_LENGTH}> and
C<$ENV{QUERY_STRING}>. It's true that this can work, but there are
also a lot of versions of this floating around that are quite simply
broken!
Please do not be tempted to reinvent the wheel. Instead, use the
CGI.pm or CGI_Lite.pm (available from CPAN), or if you're trapped in
the module-free land of perl1 .. perl4, you might look into cgi-lib.pl
(available from http://www.bio.cam.ac.uk/web/form.html).
Here's another one:
=head2 My CGI script runs from the command line but not the browser.
Can you help me fix it?
Sure, but you probably can't afford our contracting rates :-)
Seriously, if you can demonstrate that you've read the following
FAQs and that your problem isn't something simple that can be easily
answered, you'll probably receive a courteous and useful reply to
your question if you post it on comp.infosystems.www.authoring.cgi
(if it's something to do with HTTP, HTML, or the CGI protocols).
Questions that appear to be Perl questions but are really CGI ones
that are posted to comp.lang.perl.misc may not be so well received.
The useful FAQs are:
http://www.perl.com/perl/faq/idiots-guide.html
http://www3.pair.com/webthing/docs/cgi/faqs/cgifaq.shtml
http://www.perl.com/perl/faq/perl-cgi-faq.html
http://www-genome.wi.mit.edu/WWW/faqs/www-security-faq.html
http://www.boutell.com/faq/
Meanwhile, you really should learn about the -w flag. Here's a FAQ on
debugging, BTW:
=head2 How do I debug my Perl programs?
Have you used C<-w>?
Have you tried C<use strict>?
Did you check the returns of each and every system call?
Did you read L<perltrap>?
Have you tried the Perl debugger, described in L<perldebug>?
Have I mentioned the -w flag? :-)
--tom
--
Tom Christiansen tchrist@jhereg.perl.com
tmps_base = tmps_max; /* protect our mortal string */
--Larry Wall in stab.c from the perl source code
------------------------------
Date: Thu, 13 Mar 1997 15:53:15 GMT
From: ron@farmworks.com (Ronald L. Parker)
Subject: Re: We've baffled tech support, now on to Usenet...
Message-Id: <3329060e.3441595@10.0.2.33>
[emailed and posted]
I've been where you are before - I wrote my own CGI stuff without
knowing about CGI.pm, available from finer CPAN sites everywhere - so
I'm not going to be overly critical. But the Netcom CGI support team
should take a few minutes to work on their resumes; it sounds like
they're gonna need 'em.
By the way, when posting a message to comp.lang.perl.misc, it's a good
idea to use a descriptive subject line. Many of the best minds on
this newsgroup ignore anything whose topic they can't discern from the
subject. Using a subject line like yours is akin to going to a job
interview in a T-shirt and ripped jeans.
I'm surprised that the code below even compiles correctly, but if it
does it certainly will not pass the more stringent tests imposed by
the -w flag, which you always use.
On 13 Mar 1997 02:33:48 GMT, "Jason Maggard"
<jman95@ix.NOSPAMnetcom.com> wrote:
>#Receptionist.pl ~ Jason Maggard
>#! /usr/bin/local/perl5
I think the shebang line has to be the first line, and I'm not so sure
about the space after the bang. Even if it doesn't have to be, it
should be.
>#Where is that darn mail program??
>$mailprog = '/usr/lib/bin/sendmail';
>
>#And the mail is going where?
>$recipient = 'office@claytorre.com';
>
>read (STDIN, $buffer, $ENV{'content length"};
The variable you want is "CONTENT_LENGTH", and your quotes really
should match. Not to mention your parentheses.
>@pairs = split (/&/, $buffer);
>
>foreach $pair (@pairs)
>{
> ($name, $value) = split (/=/, $pair);
I know from experience that this is a bad idea. You really should use
split (/=/, $pair, 2 ) to prevent any = characters in what should be
$value from terminating it prematurely.
> #Clean up that web garbage
> $value =~ tr/+/ /;
> $value =~ s/% ([a-fA-F0-9] [a-fA-F0-9]) /pack ("C", hex($1) /eg;
> $FORM{$name} = $value;
>}
Everything so far except for your two variable initializations are
handled automatically by CGI.pm. You should definitely check this
package out - it's well documented, complete, and comes with several
great examples. In addition, it makes offline testing a breeze.
>
>#Establish blank form behaviour
>&blank_response unless $FORM{'Email'};
>
>#Send and format mail
>open (MAIL, "|$mailprog $recipient") || die "I can't seem to open
>$mailprog!\n";
>print MAIL "The following person has registered with us!\n";
>print MAIL "----------------------------------------------\n";
>print MAIL "Name: $FORM{'Name:'}\n";
>print MAIL "Address: $FORM{'Address:'}\n";
>print MAIL "
>$FORM{'City:}"".""$FORM{'State:'}"".""$Form{'Zip:'}\n";
What exactly are the double double quotation marks here supposed to
accomplish? Also, {'City:} has an unmatched quote.
Do your form field names really contain colons? Are you sure this is
legal? I try to stick to alphanumeric names, myself.
>print MAIL "==============================================\n";
>print MAIL "E-mail: $FORM{'Email'}\n";
>print MAIL "==============================================\n";
>print MAIL "$FORM{'Name:'} had this to say...\n";
>print MAIL "$FORM{'Comments'}\n";
>
>close mail
I'm sure you meant for mail to be in ALL CAPS here
>
>#Insert HTML doc here for response using print tags
>
If you haven't put this in yet, of course, you will get a server
error.
>
>
>#--------------------------------------------------------
># subroutine blank_response
>sub blank_response
>{
> print "<center> <h1>";
> print "<p> You must include an E-mail Address in order to register. Please
>re-enter your comments, or you may return to our <a
>href="http://www.claytorre.com>homepage</a>.</p></center>";
^
^ The first quote in this line closes the print statement.
Even if it didn't, it's unmatched.
> exit;
>}
--
Ron Parker
Software Engineer
Farm Works Software Come see us at http://www.farmworks.com
------------------------------
Date: Thu, 13 Mar 1997 08:29:50 GMT
From: adelton@fi.muni.cz (Honza Pazdziora)
Subject: Re: weird digit regexp behaviour
Message-Id: <adelton.858241790@aisa.fi.muni.cz>
elmegil@i1.net (Pete Hartman) writes:
> I'd think this would be a faq, but I don't see the answer in the
> regexp section of the online faq.
>
> I'm trying to match a number. I want to match 12345 but not
> 12.34.56.78; note that the latter has "." in it.
>
> The perl books both say that \d is the same as [0-9], which sounds
> to me like "just the digits 0 through 9". However, both m/\d+/ and
> m/[0-9]+/ match "12.34.56.78".
That is completely OK. The regexp matches the first digit-only
substring, which is 12. You just said with the regexp you wanted to
chack, if there are some digits in the string. If you wanted to check
for digit-only string, you'd have to use /^\d+$/.
Hope this helps.
[Cc'ed to the original poster.]
--
------------------------------------------------------------------------
Honza Pazdziora | adelton@fi.muni.cz | http://www.fi.muni.cz/~adelton/
I can take or leave it if I please
------------------------------------------------------------------------
------------------------------
Date: 13 Mar 1997 14:41:29 GMT
From: Tom Christiansen <tchrist@mox.perl.com>
Subject: Re: weird digit regexp behaviour
Message-Id: <5g93mp$ai9$3@csnews.cs.colorado.edu>
[courtesy cc of this posting sent to cited author via email]
In comp.lang.perl.misc,
elmegil@i1.net (Pete Hartman) writes:
:I'd think this would be a faq, but I don't see the answer in the
:regexp section of the online faq.
:
:I'm trying to match a number. I want to match 12345 but not
:12.34.56.78; note that the latter has "." in it.
:
:The perl books both say that \d is the same as [0-9], which sounds
:to me like "just the digits 0 through 9". However, both m/\d+/ and
:m/[0-9]+/ match "12.34.56.78".
Please thing of =~ as saying "contains" not "matches". For example
"fred" =~ /e/
"123.23" =~ /\d/
You need to think about anchors, as in ^ and $, or maybe \b, although
most folks misunderstand that one.
Meanwhile, have a FAQ:
=head2 How do I determine whether a scalar is a number/whole/integer/float?
Assuming that you don't care about IEEE notations like "NaN" or
"Infinity", you probably just want to use a regular expression.
warn "has nondigits" if /\D/;
warn "not a whole number" unless /^\d+$/;
warn "not an integer" unless /^[+-]?\d+$/
warn "not a decimal number" unless /^[+-]?\d+\.?\d*$/
warn "not a C float"
unless /^([+-]?)(?=\d|\.\d)\d*(\.\d*)?([Ee]([+-]?\d+))?$/;
Or you could check out
http://www.perl.com/CPAN/modules/by-module/String/String-Scanf-1.1.tar.gz
instead. The POSIX module (part of the standard Perl distribution)
provides the C<strtol> and C<strtod> for converting strings to double
and longs, respectively.
--tom
--
Tom Christiansen tchrist@jhereg.perl.com
If I allowed "next $label" then I'd also have to allow "goto $label",
and I don't think you really want that... :-) [now works in perl5!]
--Larry Wall in <1991Mar11.230002.27271@jpl-devvax.jpl.nasa.gov>
------------------------------
Date: Thu, 13 Mar 1997 00:15:41 GMT
From: bernie@fantasyfarm.com (Bernie Cosell)
Subject: What language do Perl REs recognize?
Message-Id: <33274678.73835889@news.swva.net>
I was wondering if anyone has characterized the languages accepted by Perl
Regular Expressions. The class is larger than the Regular Languages but
isn't the context-free languages... what is it? It has been a VERY long
time since I took language/grammar in school, but I didn't recall that
there was a class of languages between regular and CF, but I guess there
is... [also, any ideas on what sort of machine implements Perl REs? It
shouldn't need a PDA [because Perl REs can't do all Cf languages and PDAs
can], but I don't know what it might be...]
/Bernie\
--
Bernie Cosell Fantasy Farm Fibers
bernie@fantasyfarm.com Pearisburg, VA
--> Too many people, too few sheep <--
------------------------------
Date: Thu, 13 Mar 1997 10:03:51 -0500
From: Ling Wang <wang_ling@jpmorgan.com>
To: Brock Hollingsworth <"blh "@ anon.net>
Subject: Re: Who makes more $$ - Windows vs. Unix programmers?
Message-Id: <33281757.2804@jpmorgan.com>
Brock Hollingsworth wrote:
>
> The people who replied that you should, "Learn everything you can
> regardless of platform" (I'm paraphrasing of course) are dead on. If
> you focus on programming skills, not a particular platform, you are
> more likely to stay busy. I myself started in DOS, moved to Win 3.1,
> then Mac, 95, NT, UNIX, NeXT. Really, once you understand the general
> concepts, it's not too difficult to program on any platform thrown on
> your desk.
>
> Also, do it for love, not money, or don't do it at all. I've never
> met a programmer or consultant who was in it for the money who was
> worth a damn. If your just looking for a paycheck you'll end up a
> faceless drone in a large corporation grinding out C++ code for
> projects you may never see running. Follow your heart. If you like
> UNIX better, you'll do better at it. Besides, rarely do you stay
> working with the same platform for very long (unless your a big iron
> guy).
>
> Lastly, the company I'm employed by works closely with many corporate
> IS departments down to local business with just a few employees. One
> pattern we're seeing is that some of those who are using UNIX are
> trying to find a less expensive solution. The reason? UNIX
> programmers, consultants, hardware, and software cost more than
> Windows NT, 95, or even Mac, solutions. So while you might make more
> money being a UNIX programmer or consultant, you may also be pricing
> your skills out of a market with cheaper alternatives. Just the other
> day I was speaking to a consultant who told me, "Yeah, it's great. I
> make $150 an hour for UNIX consulting at company XYZ. UNIX
> adminstration isn't easy, you know." To which I replied, "Yes, that's
> why XYZ just hired us to switch them over to NT" (Actually, I was a
> bit more tactful than that). In the process of deciding on the new
> technology, company XYZ even mention this guy specifically as one of
> the reasons their support costs were so high. Not that this is sort
> of a mass migration from UNIX, but we are defintely seeing a shift.
> It's bad for the bottom line, but better for the customers.
>
Windoze programmer & administrators usually are cheaper because
they mostly migrated from the novell or pc-tech world. Their scope
of the environment is limited, knowing mainly file and print.
Unix people usually come from an environment where in depth
knowledge of the given environment exists, also knowing the
scope of the whole infrastructure.
I see WIndoze people who click this and click that, but don't
know what to do when error messages pops up besides clicking the
OK button. (If it was on a UNIX environment, an easy ldd & manybe
truss would have solved the issue easily.)
Easy solutions that could have been solve with a script is almost
unheard of in the Windoze administration world. If a task has
to be done, then buy some software to do it(And it has to have
a GUI.)
------------------------------
Date: Thu, 13 Mar 1997 16:02:02 +0100
From: Andrzej <andrzejt@free.polbox.pl>
Subject: Win32::ODBC - how to get it working in CGI scripts?
Message-Id: <332808DA.1736@free.polbox.pl>
Sorry, the question in subject is probably trivial but...
I have a very simple CGI script which works fine:
print "Content-type: text/html\n\n";
print "Hello world\n";
I am trying to use Win32::ODBC in my CGI scripts but as soon as I change
the above script to:
print "Content-type: text/html\n\n";
use Win32::ODBC;
print "Hello world";
I get a "Bad gateway" error. I've spent two days looking in FAQs but
hasn't come across anything. Please, how to get it worked? This prevents
me from using Win32::ODBC at all in my CGI scripts since they simply
don't run.
I'm using the latest version of Perl for NT and latest Win32::ODBC
package. All scripts using Win32::ODBC work for me from the command line
but not from the browser. Server is SPRY Web 1.2.
Thanks [and be gentle since I'm new to Perl and CGI :-)].
Andrzej
--
Andrzej Talarczyk
andrzejt@free.polbox.pl
------------------------------
Date: 8 Mar 97 21:33:47 GMT (Last modified)
From: Perl-Request@ruby.oce.orst.edu (Perl-Users-Digest Admin)
Subject: Digest Administrivia (Last modified: 8 Mar 97)
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------------------------------
End of Perl-Users Digest V8 Issue 109
*************************************
