[16314] in Perl-Users-Digest
Perl-Users Digest, Issue: 3726 Volume: 9
daemon@ATHENA.MIT.EDU (Perl-Users Digest)
Tue Jul 18 10:53:12 2000
Date: Tue, 18 Jul 2000 07:53:00 -0700 (PDT)
From: Perl-Users Digest <Perl-Users-Request@ruby.OCE.ORST.EDU>
To: Perl-Users@ruby.OCE.ORST.EDU (Perl-Users Digest)
Message-Id: <963931980-v9-i3726@ruby.oce.orst.edu>
Content-Type: text
Perl-Users Digest Tue, 18 Jul 2000 Volume: 9 Number: 3726
Today's topics:
Re: programming tools and techniques (Tad McClellan)
Re: programming tools and techniques ()
Re: programming tools and techniques (Keith Calvert Ivey)
Re: programming tools and techniques (Alan Coopersmith)
Re: programming tools and techniques (Dmitri V)
Re: programming tools and techniques (Jamie)
Re: programming tools and techniques ()
Re: programming tools and techniques (Jan Schaumann)
Re: Qs for professional Perl/CGI developers (Tad McClellan)
Re: Qs for professional Perl/CGI developers (Nobody)
Re: Qs for professional Perl/CGI developers ()
Re: query string problem.... (EM)
Re: question regarding file locking (Tad McClellan)
Question: system() from C++ CGI to Perl with Kernel 2.2 (Lisa Wilcox)
Re: Question: system() from C++ CGI to Perl with Kernel (Mark W. Schumann)
Quiz scripts (Geoffrey Solomon)
Digest Administrivia (Last modified: 16 Sep 99) (Perl-Users-Digest Admin)
----------------------------------------------------------------------
Date: 16 Jul 2000 13:10:03 GMT
From: tadmc@metronet.com.bbs@openbazaar.net (Tad McClellan)
Subject: Re: programming tools and techniques
Message-Id: <3bQNRS$TyN@openbazaar.net>
[ trimmed Newsgroups ]
On Sun, 16 Jul 2000 08:25:03 GMT, acunet3278@my-deja.com <acunet3278@my-deja.com> wrote:
>I am taking a beginner C language course.
That's nice.
>Could you kindly share your experience with me?
Sure.
Ask a Perl question, and someone will answer it.
--
Tad McClellan SGML Consulting
tadmc@metronet.com Perl programming
Fort Worth, Texas
------------------------------
Date: 16 Jul 2000 13:50:01 GMT
From: spike1@freenet.co.uk.bbs@openbazaar.net ()
Subject: Re: programming tools and techniques
Message-Id: <3bQOTP$UaT@openbazaar.net>
In comp.os.linux.misc acunet3278@my-deja.com wrote:
> I am taking a beginner C language course.
> Could you kindly share your experience with me?
> Where can information be found about the following topics:
> When, why and how to use a debugger?
When you compile code, one of the options is to include a symbol table
within the code that links to the source code. When you run it through a
debugger, you can see which line is executing at any point in the program,
set watchpoints (points in the program where the debugger will do something
like report the values of specified veriables), breakpoints (this causes the
program to halt at a particular point).
The simplest and most obvious use ofa debugger is to just run a program that
is known to crash, as the last thing the debugger will do is report the line
in the source code that caused the failure (which REALLY helps in tracking
down fatal bugs).
> What is it used for?
D'uh! It's *USED* for debugging programs! What did you think? Insecticide?
> When, why and how to use a Make?
When you have a medium to large program, using numerous source files, make
is used to speed up the compilation process. If you just used gcc, and
#included all the required source files each time, it's not very efficient
and can take AGES for a long program... Especially if you only altered one
line in the code to fix a bug.
With make, each source file is compiled separately and then linked together
to form the final executable. Make keeps tabs on when a file was last
updated, so if you have 4 source files say:
window.c
graphics.c
menus.c
paint.c
Where paint is the main() routine.
Now, using the gcc method, changing one line of window.c would mean you'd
have to compile all the files together to produce the final paint program.
Using make on the other hand, it would detect a change in only window.c, and
would only recompile that file, and then relink the other parts of the
program to form the new execuateble.
> What is it used for?
See above. + lots more.
Make is also capable of generating documentation, installing software, and
many other things. You just have to know how to program it.
> Additionally:
> What is a target?
Another things with make is the ability to have different options included
in the make file.
Commone examples are:
make all (Make all files and executable)
make world (something only deities tend to be able to do)
make docs (don't compile the code, just generate the documentation)
make coffee (This sends a signal to the coffee machine to make coffee)
make install (install the software you've made)
make gpl (strips out all proprietory code from a commercial program and
makes it GPL compliant)
make config/menuconfig/xconfig (make a configuration program and run it)
make clean (remover all files previously generated by make)
All these are targets.
> What is build?
You "build" software. It's another word for the compilation process, and is
also used as a method of versioning by altering the number associated with
each time the program is built.
> What is a makefile?
See above. It's the program that tells make what to do, sets the targets,
etc. No makeifle, no targets, nothing apart from an error message will
happen.
> What is a project file?
Some Developement Environments produce a project file. This can be just a
dump of all the source into one file or a complicated hierarchy of different
versions of the code, depending on the IDE.)
> Your advise, tips, comments, suggestions are welcome. I look forward to
> hearing from you. Thank you.
Just hope I've not been duped into doing your homework for you. Get a book
on C programming. Reading books is still a requirement in education, isn't
it?
[If this is your homework, I included a few slight mistakes in there to lose
you points]
:)
--
| |What to do if you find yourself stuck in a crack|
| spike1@freenet.co.uk |in the ground beneath a giant boulder, which you|
| |can't move, with no hope of rescue. |
|Andrew Halliwell BSc(hons)|Consider how lucky you are that life has been |
| in |good to you so far... |
| Computer Science | -The BOOK, Hitch-hiker's guide to the galaxy.|
------------------------------
Date: 16 Jul 2000 14:50:03 GMT
From: kcivey@cpcug.org.bbs@openbazaar.net (Keith Calvert Ivey)
Subject: Re: programming tools and techniques
Message-Id: <3bQQ8S$XPe@openbazaar.net>
tadmc@metronet.com (Tad McClellan) wrote:
>Ask a Perl question, and someone will answer it.
Except perhaps when it seems to be quoting directly from a
homework assignment, as in this case.
--
Keith C. Ivey <kcivey@cpcug.org>
Washington, DC
(Free at last from the forced spamsig of
Newsfeeds.com, cursed be their name)
------------------------------
Date: 17 Jul 2000 05:00:02 GMT
From: alanc@alum.calberkeley.org.bbs@openbazaar.net (Alan Coopersmith)
Subject: Re: programming tools and techniques
Message-Id: <3bR0F5$VOI@openbazaar.net>
acunet3278@my-deja.com writes in comp.sys.sun.apps:
|I am taking a beginner C language course.
|Could you kindly share your experience with me?
|Where can information be found about the following topics:
|
|When, why and how to use a debugger?
|What is it used for?
Since you're asking in UNIX newsgroups, I have to assume you're using
a UNIX system. If so, try running "man gdb" and "man dbx".
|When, why and how to use a Make?
|What is it used for?
|What is a target?
|What is a makefile?
"man make"
--
________________________________________________________________________
Alan Coopersmith alanc@alum.calberkeley.org
http://soar.Berkeley.EDU/~alanc/ aka: Alan.Coopersmith@Sun.COM
Working for, but definitely not speaking for, Sun Microsystems, Inc.
------------------------------
Date: 17 Jul 2000 11:40:01 GMT
From: dmvo@NOSPAM.artic.net.bbs@openbazaar.net (Dmitri V)
Subject: Re: programming tools and techniques
Message-Id: <3bRAZ1$VW8@openbazaar.net>
Thank you, Andrew, that *was* an impressive exposition. I'll keep this
text for my future reference on how to write educational materials.
Dmitri
------------------------------
Date: 17 Jul 2000 13:00:02 GMT
From: jamcquay@BOOM.hotmail.com.bbs@openbazaar.net (Jamie)
Subject: Re: programming tools and techniques
Message-Id: <3bRCd2$VGC@openbazaar.net>
to excel in your course, wy not read the text book??
<acunet3278@my-deja.com> wrote in message
news:8krrgp$ihl$1@nnrp1.deja.com...
> I am taking a beginner C language course.
> Could you kindly share your experience with me?
> Where can information be found about the following topics:
>
> When, why and how to use a debugger?
> What is it used for?
>
> When, why and how to use a Make?
> What is it used for?
>
> Additionally:
> What is a target?
> What is build?
> What is a makefile?
> What is a project file?
>
> Your advise, tips, comments, suggestions are welcome. I look forward to
> hearing from you. Thank you.
>
>
> --
> http://www.pucho.com
>
>
> Sent via Deja.com http://www.deja.com/
> Before you buy.
>
------------------------------
Date: 17 Jul 2000 20:30:11 GMT
From: spike1@freenet.co.uk.bbs@openbazaar.net ()
Subject: Re: programming tools and techniques
Message-Id: <3bROPZ$VmA@openbazaar.net>
In comp.os.linux.misc Dmitri V <dmvo@nospam.artic.net> wrote:
> Thank you, Andrew, that *was* an impressive exposition.
Thanks.
> I'll keep this text for my future reference on how to write educational
> materials.
Just remember to get rid of all the spelling mistakes and gramatical errors.
And the more deliberate inaccuracies.
(Amending the make world example, for example)
:)
--
______________________________________________________________________________
| spike1@freenet.co.uk | "Are you pondering what I'm pondering Pinky?" |
|Andrew Halliwell BSc(hons)| |
| in | "I think so brain, but this time, you control |
| Computer Science | the Encounter suit, and I'll do the voice..." |
------------------------------------------------------------------------------
------------------------------
Date: 17 Jul 2000 20:40:03 GMT
From: jschauma@netmeister.org.bbs@openbazaar.net (Jan Schaumann)
Subject: Re: programming tools and techniques
Message-Id: <3bROc4$W0I@openbazaar.net>
spike1@freenet.co.uk wrote:
>In comp.os.linux.misc acunet3278@my-deja.com wrote:
<snip>
>
>Commone examples are:
>make all (Make all files and executable)
>make world (something only deities tend to be able to do)
>make docs (don't compile the code, just generate the documentation)
>make coffee (This sends a signal to the coffee machine to make coffee)
actually... in an ideal work-environment this one sends an email/pager/be=
eper
message to the intern.
;-)
-Jan
--=20
Jan Schaumann <http://www.netmeister.org>
I know the answer! The answer lies within the heart of all mankind!
The answer is twelve? I think I'm in the wrong building.
=09=09-- Charles Schulz
------------------------------
Date: 14 Jul 2000 05:10:02 GMT
From: tadmc@metronet.com.bbs@openbazaar.net (Tad McClellan)
Subject: Re: Qs for professional Perl/CGI developers
Message-Id: <3bOW3Q$VK9@openbazaar.net>
On Fri, 14 Jul 2000 00:01:47 GMT, Pjtg0707 <Pjtg0707@Netscape.net> wrote:
>I am wondering how many of you guys are professional Perl/CGI developers?
I have been a professional Perl developer for six years
(contracting for 3 1/2 of those).
I have never written a CGI program though (except as a hobbiest).
Does that mean I can't play?
>If you work as a contractor, how do you make sure you don't get stiffed
>by your clients?
There is no Perl-specific component to that question.
So it is off-topic here. You will get way more feedback from
a newsgroup where such things are discussed, such as:
misc.business.consulting
Where this topic comes up a couple of times a week :-)
Do a deja.com search, and you won't even have to wait for the answers!
(the short answer is: get as much money upfront as you can)
If you instead want to know how to avoid stiffness when
"working across the web" (still off-topic here) then
you should ask in a newsgroup that is in some way related
to the web, such as:
comp.infosystems.www.authoring.cgi
(though I have also seen the web angle discussed on m.b.c)
>Have you ever been stiffed before?
Yes.
>Is Perl the only thing you do?
No.
>What is the general going rate for a Perl developer?
I didn't look _this_ year, but Contract Professional
magazine did a rate survey. I think I posted the Perl results
here then.
Yep:
http://www.deja.com/=dnc/[ST_rn=ps]/getdoc.xp?AN=555378426
And there is this well respected web site:
http://www.realrates.com/
I learned all this and more in m.b.c
You really should be lurking there if these things interest you,
there is wisdom just dripping off of a high percentage of
the posts there. (or there used to be anyway, I haven't been
to m.b.c for several months, (I'm too busy here answering FAQs
and sending mail bounces)).
--
Tad McClellan SGML Consulting
tadmc@metronet.com Perl programming
Fort Worth, Texas
------------------------------
Date: 17 Jul 2000 14:40:01 GMT
From: nobody@contract.Sun.COM.bbs@openbazaar.net (Nobody)
Subject: Re: Qs for professional Perl/CGI developers
Message-Id: <3bRFK1$Tvk@openbazaar.net>
In article <slrn8muvgu.eq3.tadmc@magna.metronet.com>,
Tad McClellan <tadmc@metronet.com> wrote:
>On 14 Jul 2000 20:01:45 GMT, Nobody <nobody@contract.Sun.COM> wrote:
>>>On Fri, 14 Jul 2000 00:01:47 GMT, Pjtg0707 <Pjtg0707@Netscape.net> wrote:
>>>
>
>>>>What is the general going rate for a Perl developer?
>>>
>>>
>>It varies.
>
>>Note: This is in the Boston area, where the demand is so high (for Perl
>>and anything web-related) that I could employ a dozen or so
>>of me...if only I could clone myself :-)
>
>
>One of my clients is in the Boston area.
>
>They looked for Perl programmers (with some help from me and from
>headhunters) for about six months, then gave up and had me come
>teach Perl to several of their employees instead.
>
>Boston must be hot for Perl programmers...
>
>
Blazing :-) Which makes a consultant like myself do a great
big happy dance, since I remember back to 1992 in this area
when I was unemployed for 8 months, along with many thousands
of others. I have been (figuratively speaking) fighting the
recruiters/potential employers off with a stick. I had to take
my phone number off of my resume (which is only posted on one
consultants' web site) because my answering machine was full
every day. It was nice to have the work come looking for me, not
to mention being quite a boost to the ego :-)
The market is so hot here that companies are happy to get a warm body
with half a clue. It's a great place to break into the field if you
have only a little experience. Don't know how long it's going to last,
though,so I'm taking on as much work as I can handle and making the $$
while they're still flowing freely. But if the rate of new construction
and low office vacancies is anything to go by, it looks like things will
be pretty good for a while. Sun Microsystems (one of my contracts) has
built 4 huge building for their campus, and is starting on the next 4.
They have something like 200 job openings here, and are paying premiums
to employees who refer engineers/developers. Cisco Systems just bought
a huge parcel of land in the 'burbs to build an east coast campus. And
there are dozens of networking/internet startups springing up all over.
All in all, it's a good time to be a geek in New England :-)
Anita
------------------------------
Date: 17 Jul 2000 18:20:01 GMT
From: schnurmann@my-deja.com.bbs@openbazaar.net ()
Subject: Re: Qs for professional Perl/CGI developers
Message-Id: <3bRL71$WLl@openbazaar.net>
This is yet another reason why companies need to learn the value of
telecommutting.
In article <slrn8muvgu.eq3.tadmc@magna.metronet.com>,
tadmc@metronet.com (Tad McClellan) wrote:
> On 14 Jul 2000 20:01:45 GMT, Nobody <nobody@contract.Sun.COM> wrote:
> >>On Fri, 14 Jul 2000 00:01:47 GMT, Pjtg0707 <Pjtg0707@Netscape.net>
wrote:
> >>
>
> >>>What is the general going rate for a Perl developer?
> >>
> >>
> >It varies.
>
> >Note: This is in the Boston area, where the demand is so high (for
Perl
> >and anything web-related) that I could employ a dozen or so
> >of me...if only I could clone myself :-)
>
> One of my clients is in the Boston area.
>
> They looked for Perl programmers (with some help from me and from
> headhunters) for about six months, then gave up and had me come
> teach Perl to several of their employees instead.
>
> Boston must be hot for Perl programmers...
>
> --
> Tad McClellan SGML Consulting
> tadmc@metronet.com Perl programming
> Fort Worth, Texas
>
Sent via Deja.com http://www.deja.com/
Before you buy.
------------------------------
Date: 17 Jul 2000 03:10:10 GMT
From: me@privacy.net.bbs@openbazaar.net (EM)
Subject: Re: query string problem....
Message-Id: <3bQjLZ$Vy1@openbazaar.net>
I am new to perl to but this code will work but i am not sure if its the
best way to do it
$id = $ENV{'QUERY_STRING'};
change it to
($useless,$id) = split(/\=/,$ENV{'QUERY_STRING'});
"cam" <cam@home.com> wrote in message
news:Tcub5.10287$8u4.137828@news1.rdc1.bc.home.com...
> Hi:
>
> I'm newish to perl. I'm trying to retrieve the data from a query string.
> Can't seem to dump the "id=" part in my perl script. Here's a simple
example
> to illustrate:
>
>
> html file:
> ======
> <a href="/cgi-bin/getlink.pl?id=0">ibm</a>
> <a href="/cgi-bin/getlink.pl?id=1">apple</a>
> <a href="/cgi-bin/getlink.pl?id=2">linux</a>
>
> Perl File:
> =======
> #!/usr/bin/perl
>
> print "Content-type: text/html\n\n";
> use LWP::Simple;
>
> $id = $ENV{'QUERY_STRING'};
>
> @gothere = ();
> $gothere[0]="ibm";
> $gothere[1]="apple";
> $gothere[2]="linux";
>
> print "@gothere[$ENV{'QUERY_STRING'}]\n";
>
>
> Problem is that this returns:
> id=xxxx
>
> what I want is simply the xxxx WITHOUT the id= on it. any ideas?? Why
> is it returning the id= part and how can I get rid of it?
>
> Thanks!!!!
>
> Cam
>
>
------------------------------
Date: 11 Jul 2000 16:50:02 GMT
From: tadmc@metronet.com.bbs@openbazaar.net (Tad McClellan)
Subject: Re: question regarding file locking
Message-Id: <3bMXcP$Wns@openbazaar.net>
On Tue, 11 Jul 2000 23:19:28 +0800, Thomas Haenel <thaenel@one.net.au> wrote:
>could someone tell me the best way to lock files so that only one
>process at a time can read/write a file.
perldoc -f flock
perldoc -q "\block"
"How can I lock a file?"
"Why can't I just open(FH, ">file.lock")?"
"I still don't get locking. I just want to
increment the number in the file. How can I do this?"
>At the moment I'm using a
>simple
>
>while ( -e "datalock" ) {sleep 1;};
You lock files to avoid a "race condition".
You have just *created* a race condition.
This code will NOT protect your data from corruption.
There is more info about file locking in:
perldoc perlopentut
> system ("touch datalock");
What if the "touch" fails?
Wouldn't you like to know if that happens?
If so, then:
!system ("touch datalock") || die "problem touching datalock $!";
^ ^^
^ ^^
>Is there a better way ?
As your way does not avoid the situation that you are trying do
avoid (i.e. it does not work), just about any "way" would be "better" :-)
--
Tad McClellan SGML Consulting
tadmc@metronet.com Perl programming
Fort Worth, Texas
------------------------------
Date: 17 Jul 2000 18:00:01 GMT
From: lwilcox@emory.edu.bbs@openbazaar.net (Lisa Wilcox)
Subject: Question: system() from C++ CGI to Perl with Kernel 2.2.16
Message-Id: <3bRKU1$UWO@openbazaar.net>
Hello all,
I've got a C++ CGI making a syscall to a Perl program on a Red Hat Linux
test server with kernel 2.2.5, and working beautifully. On another
system where the main difference is the kernel (2.2.16), it doesn't work
at all. I have combed through all relevant logs in /var/log and there
are no error messages whatsoever. It appears to be running the Perl
program, as error messages from its system calls are being logged to
/var/log/httpd/error_log. I've tried using popen() instead, with no
success. The C++ CGI compiles cleanly and runs as expected with
exception of the system call. The Perl program runs as expected when
run from the command line.
What's the problem?!?! Is this a security issue? Is this just a bug
and all I need is a patch? I'm using Perl 5.005_03, glibc 2.1.2-11,
apache 1.3.12, and compiling with g++. I *really* don't want to embed a
Perl interpreter because I think its overkill for what I'm trying to
do. However, if the problem is a security issue blocking the execution,
either within Apache or the kernel, I would be willing to do it. If
someone could recommend an example that makes sense, I would appreciate
it. All I want to do is run the program and have the results print back
to the user.
Any solutions to the problem would be joyously received.
Thanks,
--
Lisa Wilcox
SAGE Systems Developer
SAGE Project: http://sage.library.emory.edu/
Woodruff Library/Emory University
Email: lwilcox@emory.edu
Phone: 404-727-0961
------------------------------
Date: 18 Jul 2000 00:10:01 GMT
From: catfood@apk.net.bbs@openbazaar.net (Mark W. Schumann)
Subject: Re: Question: system() from C++ CGI to Perl with Kernel 2.2.16
Message-Id: <3bRUCQ$UP_@openbazaar.net>
In article <3973477B.6ABB6E9D@emory.edu>,
Lisa Wilcox <lwilcox@emory.edu> wrote:
>I've got a C++ CGI making a syscall to a Perl program on a Red Hat Linux
>test server with kernel 2.2.5, and working beautifully. On another
>system where the main difference is the kernel (2.2.16), it doesn't work
>at all. I have combed through all relevant logs in /var/log and there
What do you mean by "doesn't work at all"? Does the Perl program
send no output at all to the browser? Something else?
>are no error messages whatsoever. It appears to be running the Perl
>program, as error messages from its system calls are being logged to
>/var/log/httpd/error_log. I've tried using popen() instead, with no
>success. The C++ CGI compiles cleanly and runs as expected with
>exception of the system call. The Perl program runs as expected when
>run from the command line.
Are you using -w and "use strict"? Those go a long way towards
identifying problems.
Also, are you using the CGI module (as in "use CGI;")? If not, well,
the consensus on this group is that you're just opening a can of worms
by not using it and thus reinventing the wheel.
Read up on the concept of "tainted" data in "man perlsec" too.
Finally, take a look at the Idiot's Guide to Solving Perl CGI Problems.
The "official" site for this seems to be down at the moment, so I'll
just suggest you look for "idiot's perl cgi" or somesuch on a search
engine.
>What's the problem?!?! Is this a security issue? Is this just a bug
>and all I need is a patch? I'm using Perl 5.005_03, glibc 2.1.2-11,
>apache 1.3.12, and compiling with g++. I *really* don't want to embed a
>Perl interpreter because I think its overkill for what I'm trying to
>do. However, if the problem is a security issue blocking the execution,
>either within Apache or the kernel, I would be willing to do it. If
>someone could recommend an example that makes sense, I would appreciate
>it. All I want to do is run the program and have the results print back
>to the user.
Wow... you're proposing a lot of solutions but not giving us much to go
on here. One step at a time.
------------------------------
Date: 17 Jul 2000 09:50:04 GMT
From: geoff@solomons.org.bbs@openbazaar.net (Geoffrey Solomon)
Subject: Quiz scripts
Message-Id: <3bR7fS$WLb@openbazaar.net>
Hi. I am looking to find a quiz script on the internet that lets you offer
questions a screen at a time (rather than all on one page). Does anyone know
of one, please?
------------------------------
Date: 16 Sep 99 21:33:47 GMT (Last modified)
From: Perl-Users-Request@ruby.oce.orst.edu (Perl-Users-Digest Admin)
Subject: Digest Administrivia (Last modified: 16 Sep 99)
Message-Id: <null>
Administrivia:
The Perl-Users Digest is a retransmission of the USENET newsgroup
comp.lang.perl.misc. For subscription or unsubscription requests, send
the single line:
subscribe perl-users
or:
unsubscribe perl-users
to almanac@ruby.oce.orst.edu.
| NOTE: The mail to news gateway, and thus the ability to submit articles
| through this service to the newsgroup, has been removed. I do not have
| time to individually vet each article to make sure that someone isn't
| abusing the service, and I no longer have any desire to waste my time
| dealing with the campus admins when some fool complains to them about an
| article that has come through the gateway instead of complaining
| to the source.
To submit articles to comp.lang.perl.announce, send your article to
clpa@perl.com.
To request back copies (available for a week or so), send your request
to almanac@ruby.oce.orst.edu with the command "send perl-users x.y",
where x is the volume number and y is the issue number.
For other requests pertaining to the digest, send mail to
perl-users-request@ruby.oce.orst.edu. Do not waste your time or mine
sending perl questions to the -request address, I don't have time to
answer them even if I did know the answer.
------------------------------
End of Perl-Users Digest V9 Issue 3726
**************************************
