[25004] in Perl-Users-Digest
Perl-Users Digest, Issue: 7254 Volume: 10
daemon@ATHENA.MIT.EDU (Perl-Users Digest)
Fri Oct 15 06:07:00 2004
Date: Fri, 15 Oct 2004 03:05:05 -0700 (PDT)
From: Perl-Users Digest <Perl-Users-Request@ruby.OCE.ORST.EDU>
To: Perl-Users@ruby.OCE.ORST.EDU (Perl-Users Digest)
Perl-Users Digest Fri, 15 Oct 2004 Volume: 10 Number: 7254
Today's topics:
Re: hard references/arrays <tintin@invalid.invalid>
Re: is there a better way to mkdir? <tintin@invalid.invalid>
Re: is there a better way to mkdir? (Anno Siegel)
Re: is there a better way to mkdir? (Anno Siegel)
Posting Guidelines for comp.lang.perl.misc ($Revision: tadmc@augustmail.com
Re: python for perl programmers? <markus.cl@gmx.de>
Re: References to an array in a foreach <someone@example.com>
Re: References to an array in a foreach <tadmc@augustmail.com>
Re: References to an array in a foreach <tadmc@augustmail.com>
Re: Restricting a program to one running instance (Anno Siegel)
Re: setting cookies (mod_perl) <usenet@root.mailshell.com>
Re: String and Array Programming in Perl <tadmc@augustmail.com>
Re: String and Array Programming in Perl <tadmc@augustmail.com>
Re: Top posting (was Re: Concatenating an array into on <tadmc@augustmail.com>
Re: Top posting (was Re: Concatenating an array into on <tadmc@augustmail.com>
Re: Top posting (was Re: Concatenating an array into on <tadmc@augustmail.com>
Re: Top posting (was Re: Concatenating an array into on <do-not-use@invalid.net>
Re: undef takes forever <bart.lateur@pandora.be>
use CGI question <nospam@nospam.com>
Re: use CGI question <tony_curtis32@yahoo.com>
Re: use CGI question <nospam@bigpond.com>
Re: use CGI question (Charles DeRykus)
Digest Administrivia (Last modified: 6 Apr 01) (Perl-Users-Digest Admin)
----------------------------------------------------------------------
Date: Fri, 15 Oct 2004 19:00:34 +1300
From: "Tintin" <tintin@invalid.invalid>
Subject: Re: hard references/arrays
Message-Id: <2t97a4F1rc1ovU1@uni-berlin.de>
"Brian McCauley" <nobull@mail.com> wrote in message
news:cklnl4$ied$1@sun3.bham.ac.uk...
> Replace the separate variables @addresses and @elements with a single hash
> of arrays (say, %record) so @addresses becomes @{$record{ADDRESS}} and
> @elements becomes @{$record{ELEMENT}}.
>
>> Note that the loop is needed to pad out the insert_record array with
>> undef values if the array being referenced is less than 6 elements.
>
> No it isn't, a slice will do that perfectly well.
>
> push @insert_record => map { @$_[0..5] } @record{'ADDRESS','ELEMENT'};
Ahh, exactly what I need. Thanks for helping out.
BTW, needs to be
push @insert_record => map { @{$_}[0..5] } @record{'ADDRESS','ELEMENT'};
------------------------------
Date: Fri, 15 Oct 2004 19:34:16 +1300
From: "Tintin" <tintin@invalid.invalid>
Subject: Re: is there a better way to mkdir?
Message-Id: <2t9998F1tki1pU1@uni-berlin.de>
"Gary E. Ansok" <ansok@alumni.caltech.edu> wrote in message
news:ckmv44$232$1@naig.caltech.edu...
> In article <bf0b47ca.0410140756.27b35107@posting.google.com>,
> wana <ioneabu@yahoo.com> wrote:
>>I use mkdir in a program which recursively searches through a
>>directory searching for files of a particular type and recreating the
>>directory structure elsewhere and the files (which happen to be images
>>which get manipulated by ImageMagick along the way).
>>
>>In recreating the directory structure, I sometimes come across the
>>error:
>>
>>No such file or directory
>>
>>which is due to trying to create multiple directory levels at once
>>which is not allowed. While this probably is a problem in my program
>>logic (that is another whole issue, but I didn't want to ask too much
>>at once), I was wondering, why can't I create a whole path at once
>>like:
>>
>>mkdir mouse/cat/dog
>>
>>where none of the three directories exist yet.
>
> Have you tried the mkpath() function in the File::Path module?
>
> use File::Path;
>
> mkpath('mouse/cat/dog', 0, 0755);
>
> (change the 0 to 1 and it will print out each directory it creates.)
>
> This is a standard module, so you should have it available already.
and I'm surprised that you're the only person (so far), that has suggested
this obvious answer.
I'm surprised the regulars went for their roll-their-own methods.
------------------------------
Date: 15 Oct 2004 09:27:02 GMT
From: anno4000@lublin.zrz.tu-berlin.de (Anno Siegel)
Subject: Re: is there a better way to mkdir?
Message-Id: <cko556$eja$1@mamenchi.zrz.TU-Berlin.DE>
wana <ioneabu@yahoo.com> wrote in comp.lang.perl.misc:
> > > sub SuperMkdir
> > > {
> > > my $path = shift;
> > > my $hold = $path;
> > > while (mkdir($path) == 0)
> > > {
> > > do
> > > {
> > > $path =~ s/[^\/]+\/*$//;
> > > }
> > > while (mkdir($path) == 0);
> > ^^
> > That is wrong. mkdir returns true on success.
> >
>
> I am actually testing for failure. Each time mkdir fails, I chop of
> the end of the path and try again until I succeed. The outer loop
> repeats this process over and over until the whole path is
> successfully created and the loops are exited. I tested it before
> posting on a few examples.
Ah... sorry. I admit I didn't really follow the logic of your program.
All I saw was a big old regex and a "do {} while..." loop and thought,
we don't need that shit... :)
> > > $path = $hold;
> > > }
> > > }
> >
> > Well, I guess it might work, but it is more convoluted than it has to be.
> > I wouldn't use pattern substitution to extract the partial path names,
> > I'd split on the directory separator and build the paths from the parts.
> > That can be done in a standard for-loop.
> >
> > my $dir;
> > for ( split m{/}, $path ) {
> > $dir .= '/' if length $dir;
> > $dir .= $_;
> > mkdir $dir or last;
> > }
> >
> > or even
> >
> > my @parts = split m{/}, $dir;
> > mkdir join( '/', @$_) for map [ @parts[ 0 .. $_]], 0 .. $#parts;
> >
> > Anno
>
> I like your way. I was thinking that I had to account for different
> ways the path might appear:
>
> //dog/cat//mouse/
> dog/cat/mouse
> ./dog/cat/mouse//
>
> The double //'s might come up as a side effect of how a program puts
> paths together. Split should still work because you will just get an
> empty string in the array which will not change anything.
Normalizing the path is another issue. I would treat that logically
instead of letting the file system detect that parts of the path
have already been created. If it's only multiple slashes, split()
can be modified accordingly. Things like "dog/cat/../cat/mouse"
deserve separate processing.
Speaking of normalization, if the $path is always terminated with
"/", your original regex approach becomes attractive again:
for ( $path ) {
$_ .= "/" unless m{/$};
mkdir substr( $_, 0, pos) while m{.*?/}g;
}
Oh, and ... yes, I'm aware that there are standard modules that
do this. It may still be illuminating to explore code variants.
Anno
------------------------------
Date: 15 Oct 2004 09:50:32 GMT
From: anno4000@lublin.zrz.tu-berlin.de (Anno Siegel)
Subject: Re: is there a better way to mkdir?
Message-Id: <cko6h8$ffa$2@mamenchi.zrz.TU-Berlin.DE>
Abigail <abigail@abigail.nl> wrote in comp.lang.perl.misc:
> Anno Siegel (anno4000@lublin.zrz.tu-berlin.de) wrote on MMMMLXII
> September MCMXCIII in <URL:news:ckmaho$ba0$2@mamenchi.zrz.TU-Berlin.DE>:
> :) Richard Gration <richard@zync.co.uk> wrote in comp.lang.perl.misc:
> :) > On Thu, 14 Oct 2004 08:56:27 -0700, wana wrote:
> :) >
> :) > > I was wondering, why can't I create a whole path at once
> :) > > like:
> :) > >
> :) > > mkdir mouse/cat/dog
> :) > >
> :) > > where none of the three directories exist yet.
> :) > >
> :) > > This is what I came up with, but I thought there might be another way
> :) > > or a better way to do it.
> :) >
> :) > Dunno about a perl solution but unix mkdir supports a -p flag for this, so
> :)
> :) There is no such thing as "unix mkdir". Most modern brands of unix
> :) appear to have the -p flag for mkdir, but I wouldn't bet my portability
> :) on it.
>
> The POSIX requirement for support of options of utilities is often not
> broad. But it does require -p for mkdir.
All I knew when I wrote my reply was that "-p" wasn't always there
for mkdir. I remember thinking "Ah, finally..." when it appeared.
> Portability is overrated anyway. I claim that the fast majority of the
> Perl scripts that are written will only run on one system anyway.
True for most programs written by yourself for yourself. Not true
for publishable code, as for CPAN.
Anno
------------------------------
Date: Fri, 15 Oct 2004 02:22:05 -0500
From: tadmc@augustmail.com
Subject: Posting Guidelines for comp.lang.perl.misc ($Revision: 1.5 $)
Message-Id: <saKdnT6fsqkA5_LcRVn-og@august.net>
Outline
Before posting to comp.lang.perl.misc
Must
- Check the Perl Frequently Asked Questions (FAQ)
- Check the other standard Perl docs (*.pod)
Really Really Should
- Lurk for a while before posting
- Search a Usenet archive
If You Like
- Check Other Resources
Posting to comp.lang.perl.misc
Is there a better place to ask your question?
- Question should be about Perl, not about the application area
How to participate (post) in the clpmisc community
- Carefully choose the contents of your Subject header
- Use an effective followup style
- Speak Perl rather than English, when possible
- Ask perl to help you
- Do not re-type Perl code
- Provide enough information
- Do not provide too much information
- Do not post binaries, HTML, or MIME
Social faux pas to avoid
- Asking a Frequently Asked Question
- Asking a question easily answered by a cursory doc search
- Asking for emailed answers
- Beware of saying "doesn't work"
- Sending a "stealth" Cc copy
Be extra cautious when you get upset
- Count to ten before composing a followup when you are upset
- Count to ten after composing and before posting when you are upset
-----------------------------------------------------------------
Posting Guidelines for comp.lang.perl.misc ($Revision: 1.5 $)
This newsgroup, commonly called clpmisc, is a technical newsgroup
intended to be used for discussion of Perl related issues (except job
postings), whether it be comments or questions.
As you would expect, clpmisc discussions are usually very technical in
nature and there are conventions for conduct in technical newsgroups
going somewhat beyond those in non-technical newsgroups.
The article at:
http://www.catb.org/~esr/faqs/smart-questions.html
describes how to get answers from technical people in general.
This article describes things that you should, and should not, do to
increase your chances of getting an answer to your Perl question. It is
available in POD, HTML and plain text formats at:
http://mail.augustmail.com/~tadmc/clpmisc.shtml
For more information about netiquette in general, see the "Netiquette
Guidelines" at:
http://andrew2.andrew.cmu.edu/rfc/rfc1855.html
A note to newsgroup "regulars":
Do not use these guidelines as a "license to flame" or other
meanness. It is possible that a poster is unaware of things
discussed here. Give them the benefit of the doubt, and just
help them learn how to post, rather than assume
A note about technical terms used here:
In this document, we use words like "must" and "should" as
they're used in technical conversation (such as you will
encounter in this newsgroup). When we say that you *must* do
something, we mean that if you don't do that something, then
it's unlikely that you will benefit much from this group.
We're not bossing you around; we're making the point without
lots of words.
Do *NOT* send email to the maintainer of these guidelines. It will be
discarded unread. The guidelines belong to the newsgroup so all
discussion should appear in the newsgroup. I am just the secretary that
writes down the consensus of the group.
Before posting to comp.lang.perl.misc
Must
This section describes things that you *must* do before posting to
clpmisc, in order to maximize your chances of getting meaningful replies
to your inquiry and to avoid getting flamed for being lazy and trying to
have others do your work.
The perl distribution includes documentation that is copied to your hard
drive when you install perl. Also installed is a program for looking
things up in that (and other) documentation named 'perldoc'.
You should either find out where the docs got installed on your system,
or use perldoc to find them for you. Type "perldoc perldoc" to learn how
to use perldoc itself. Type "perldoc perl" to start reading Perl's
standard documentation.
Check the Perl Frequently Asked Questions (FAQ)
Checking the FAQ before posting is required in Big 8 newsgroups in
general, there is nothing clpmisc-specific about this requirement.
You are expected to do this in nearly all newsgroups.
You can use the "-q" switch with perldoc to do a word search of the
questions in the Perl FAQs.
Check the other standard Perl docs (*.pod)
The perl distribution comes with much more documentation than is
available for most other newsgroups, so in clpmisc you should also
see if you can find an answer in the other (non-FAQ) standard docs
before posting.
It is *not* required, or even expected, that you actually *read* all of
Perl's standard docs, only that you spend a few minutes searching them
before posting.
Try doing a word-search in the standard docs for some words/phrases
taken from your problem statement or from your very carefully worded
"Subject:" header.
Really Really Should
This section describes things that you *really should* do before posting
to clpmisc.
Lurk for a while before posting
This is very important and expected in all newsgroups. Lurking means
to monitor a newsgroup for a period to become familiar with local
customs. Each newsgroup has specific customs and rituals. Knowing
these before you participate will help avoid embarrassing social
situations. Consider yourself to be a foreigner at first!
Search a Usenet archive
There are tens of thousands of Perl programmers. It is very likely
that your question has already been asked (and answered). See if you
can find where it has already been answered.
One such searchable archive is:
http://groups.google.com/advanced_group_search
If You Like
This section describes things that you *can* do before posting to
clpmisc.
Check Other Resources
You may want to check in books or on web sites to see if you can
find the answer to your question.
But you need to consider the source of such information: there are a
lot of very poor Perl books and web sites, and several good ones
too, of course.
Posting to comp.lang.perl.misc
There can be 200 messages in clpmisc in a single day. Nobody is going to
read every article. They must decide somehow which articles they are
going to read, and which they will skip.
Your post is in competition with 199 other posts. You need to "win"
before a person who can help you will even read your question.
These sections describe how you can help keep your article from being
one of the "skipped" ones.
Is there a better place to ask your question?
Question should be about Perl, not about the application area
It can be difficult to separate out where your problem really is,
but you should make a conscious effort to post to the most
applicable newsgroup. That is, after all, where you are the most
likely to find the people who know how to answer your question.
Being able to "partition" a problem is an essential skill for
effectively troubleshooting programming problems. If you don't get
that right, you end up looking for answers in the wrong places.
It should be understood that you may not know that the root of your
problem is not Perl-related (the two most frequent ones are CGI and
Operating System related), so off-topic postings will happen from
time to time. Be gracious when someone helps you find a better place
to ask your question by pointing you to a more applicable newsgroup.
How to participate (post) in the clpmisc community
Carefully choose the contents of your Subject header
You have 40 precious characters of Subject to win out and be one of
the posts that gets read. Don't waste them. Take care while
composing them, they are the key that opens the door to getting an
answer.
Spend them indicating what aspect of Perl others will find if they
should decide to read your article.
Do not spend them indicating "experience level" (guru, newbie...).
Do not spend them pleading (please read, urgent, help!...).
Do not spend them on non-Subjects (Perl question, one-word
Subject...)
For more information on choosing a Subject see "Choosing Good
Subject Lines":
http://www.cpan.org/authors/id/D/DM/DMR/subjects.post
Part of the beauty of newsgroup dynamics, is that you can contribute
to the community with your very first post! If your choice of
Subject leads a fellow Perler to find the thread you are starting,
then even asking a question helps us all.
Use an effective followup style
When composing a followup, quote only enough text to establish the
context for the comments that you will add. Always indicate who
wrote the quoted material. Never quote an entire article. Never
quote a .signature (unless that is what you are commenting on).
Intersperse your comments *following* each section of quoted text to
which they relate. Unappreciated followup styles are referred to as
"top-posting", "Jeopardy" (because the answer comes before the
question), or "TOFU" (Text Over, Fullquote Under).
Reversing the chronology of the dialog makes it much harder to
understand (some folks won't even read it if written in that style).
For more information on quoting style, see:
http://web.presby.edu/~nnqadmin/nnq/nquote.html
Speak Perl rather than English, when possible
Perl is much more precise than natural language. Saying it in Perl
instead will avoid misunderstanding your question or problem.
Do not say: I have variable with "foo\tbar" in it.
Instead say: I have $var = "foo\tbar", or I have $var = 'foo\tbar',
or I have $var = <DATA> (and show the data line).
Ask perl to help you
You can ask perl itself to help you find common programming mistakes
by doing two things: enable warnings (perldoc warnings) and enable
"strict"ures (perldoc strict).
You should not bother the hundreds/thousands of readers of the
newsgroup without first seeing if a machine can help you find your
problem. It is demeaning to be asked to do the work of a machine. It
will annoy the readers of your article.
You can look up any of the messages that perl might issue to find
out what the message means and how to resolve the potential mistake
(perldoc perldiag). If you would like perl to look them up for you,
you can put "use diagnostics;" near the top of your program.
Do not re-type Perl code
Use copy/paste or your editor's "import" function rather than
attempting to type in your code. If you make a typo you will get
followups about your typos instead of about the question you are
trying to get answered.
Provide enough information
If you do the things in this item, you will have an Extremely Good
chance of getting people to try and help you with your problem!
These features are a really big bonus toward your question winning
out over all of the other posts that you are competing with.
First make a short (less than 20-30 lines) and *complete* program
that illustrates the problem you are having. People should be able
to run your program by copy/pasting the code from your article. (You
will find that doing this step very often reveals your problem
directly. Leading to an answer much more quickly and reliably than
posting to Usenet.)
Describe *precisely* the input to your program. Also provide example
input data for your program. If you need to show file input, use the
__DATA__ token (perldata.pod) to provide the file contents inside of
your Perl program.
Show the output (including the verbatim text of any messages) of
your program.
Describe how you want the output to be different from what you are
getting.
If you have no idea at all of how to code up your situation, be sure
to at least describe the 2 things that you *do* know: input and
desired output.
Do not provide too much information
Do not just post your entire program for debugging. Most especially
do not post someone *else's* entire program.
Do not post binaries, HTML, or MIME
clpmisc is a text only newsgroup. If you have images or binaries
that explain your question, put them in a publically accessible
place (like a Web server) and provide a pointer to that location. If
you include code, cut and paste it directly in the message body.
Don't attach anything to the message. Don't post vcards or HTML.
Many people (and even some Usenet servers) will automatically filter
out such messages. Many people will not be able to easily read your
post. Plain text is something everyone can read.
Social faux pas to avoid
The first two below are symptoms of lots of FAQ asking here in clpmisc.
It happens so often that folks will assume that it is happening yet
again. If you have looked but not found, or found but didn't understand
the docs, say so in your article.
Asking a Frequently Asked Question
It should be understood that you may have missed the applicable FAQ
when you checked, which is not a big deal. But if the Frequently
Asked Question is worded similar to your question, folks will assume
that you did not look at all. Don't become indignant at pointers to
the FAQ, particularly if it solves your problem.
Asking a question easily answered by a cursory doc search
If folks think you have not even tried the obvious step of reading
the docs applicable to your problem, they are likely to become
annoyed.
If you are flamed for not checking when you *did* check, then just
shrug it off (and take the answer that you got).
Asking for emailed answers
Emailed answers benefit one person. Posted answers benefit the
entire community. If folks can take the time to answer your
question, then you can take the time to go get the answer in the
same place where you asked the question.
It is OK to ask for a *copy* of the answer to be emailed, but many
will ignore such requests anyway. If you munge your address, you
should never expect (or ask) to get email in response to a Usenet
post.
Ask the question here, get the answer here (maybe).
Beware of saying "doesn't work"
This is a "red flag" phrase. If you find yourself writing that,
pause and see if you can't describe what is not working without
saying "doesn't work". That is, describe how it is not what you
want.
Sending a "stealth" Cc copy
A "stealth Cc" is when you both email and post a reply without
indicating *in the body* that you are doing so.
Be extra cautious when you get upset
Count to ten before composing a followup when you are upset
This is recommended in all Usenet newsgroups. Here in clpmisc, most
flaming sub-threads are not about any feature of Perl at all! They
are most often for what was seen as a breach of netiquette. If you
have lurked for a bit, then you will know what is expected and won't
make such posts in the first place.
But if you get upset, wait a while before writing your followup. I
recommend waiting at least 30 minutes.
Count to ten after composing and before posting when you are upset
After you have written your followup, wait *another* 30 minutes
before committing yourself by posting it. You cannot take it back
once it has been said.
AUTHOR
Tad McClellan <tadmc@augustmail.com> and many others on the
comp.lang.perl.misc newsgroup.
------------------------------
Date: Thu, 14 Oct 2004 22:44:47 -0400
From: Markus Dehmann <markus.cl@gmx.de>
Subject: Re: python for perl programmers?
Message-Id: <2t8rt1F1r2i2pU1@uni-berlin.de>
Chris Richmond - MD6-FDC ~ wrote:
> Hi Folks,
>
> Not out of choice, I'm going to have to learn python on
> Windows. I've used perl on Unix forever and totally hate
> the idea, but like I said, no choice.
>
> What I'm looking for is a some sort of a Learning python
> for perl programmers. I don't think I need plain old
> programming help, but something that will translate all
> those nice perl concepts into the equivelant python
> constructs.
I asked pretty much the same question in comp.lang.python. You can check it
out, it's the same subject "Python for Perl programmers?", from Sep 20,
2004, with 20 postings.
Here is what they said, in a nutshell:
1) http://pleac.sourceforge.net/ (this is really exactly what you want)
2) http://www.python.org/moin/PerlPhrasebook
3) > "Programming Python" by Mark Lutz I found to be helpful as it has lots
> of examples.
> "Python Essential Reference" by David Beazley was useful for its
> Python quickstart and library reference.
4) >the 1st 10 chapters in David Beazley's Python
>Essential Reference are great -- they give a short but thorough
>introduction to the core features. For a more comprehensive and
>recent treatment, take a look at Python in a Nutshell and The Python
>Cookbook.
Markus
------------------------------
Date: Fri, 15 Oct 2004 02:31:12 GMT
From: "John W. Krahn" <someone@example.com>
Subject: Re: References to an array in a foreach
Message-Id: <QDGbd.21724$qU.17281@clgrps13>
David H. Adler wrote:
> On 2004-10-14, A. Sinan Unur <usa1@llenroc.ude.invalid> wrote:
>
>>What you really want to use is a hash for animals
>
>
> Really, this sounds like something the SPCA might come after you for...
> :-)
Or PETA
John
--
use Perl;
program
fulfillment
------------------------------
Date: Thu, 14 Oct 2004 23:01:54 -0500
From: Tad McClellan <tadmc@augustmail.com>
Subject: Re: References to an array in a foreach
Message-Id: <slrncmuiti.59s.tadmc@magna.augustmail.com>
A. Sinan Unur <usa1@llenroc.ude.invalid> wrote:
> "A. Sinan Unur" <1usa@llenroc.ude.invalid> wrote in
> news:Xns9582A2C548DB0asu1cornelledu@132.236.56.8:
>> David Green <mail.david@dsl.pipex.com> wrote in
>> news:pan.2004.10.14.19.59.52.96858@dsl.pipex.com:
>>> foreach $thiskey (@$thatkey) { # Here I try to dereference the
>>> array print $thiskey . ","; # and presumably fail?
> I do not know where the word 'array'
> came from in my copy.
Looks like it came from word-wrap to me.
--
Tad McClellan SGML consulting
tadmc@augustmail.com Perl programming
Fort Worth, Texas
------------------------------
Date: Thu, 14 Oct 2004 23:03:04 -0500
From: Tad McClellan <tadmc@augustmail.com>
Subject: Re: References to an array in a foreach
Message-Id: <slrncmuivo.59s.tadmc@magna.augustmail.com>
David Green <mail.david@dsl.pipex.com> wrote:
> didn't want to copy and paste a lot of
> of superfluos code
So then, only copy and paste the pertinent code.
--
Tad McClellan SGML consulting
tadmc@augustmail.com Perl programming
Fort Worth, Texas
------------------------------
Date: 15 Oct 2004 09:50:04 GMT
From: anno4000@lublin.zrz.tu-berlin.de (Anno Siegel)
Subject: Re: Restricting a program to one running instance
Message-Id: <cko6gc$ffa$1@mamenchi.zrz.TU-Berlin.DE>
Michele Dondi <bik.mido@tiscalinet.it> wrote in comp.lang.perl.misc:
> On 14 Oct 2004 11:33:42 GMT, anno4000@lublin.zrz.tu-berlin.de (Anno
> Siegel) wrote:
>
> >> If you make the pidfile secure, then you can simply check if that pid is
> >> still running (kill 0 => $pid); if you're worried about pid wraparound
> >> then you really need to get some positive check that the process
> >> concerned is one of yours, such as (in the extreme case) connecting to a
> >> Unix-domain socket the other copy is listening on and performing a
> >> secure authentication exchange.
> >
> >That should only be necessary if the lock-able process must run under
> >various user-id's. If it is always run under the same id, the lock
> >file permissions should only allow the owner to open the file. Also,
> >(perhaps needless to say) the lock file must be specific to that process,
> >in particular, no other program (of yours) should ever lock that file.
> >Then, unless the uid is compromised, if there is a lock, it *must*
> >belong to the one process that can hold it.
>
> Sorry if I'm being overly dumb, but when you say "lock" do you mean
> lock() or simply a suitably sysopen()ed lockfile or both? (Intuition
> suggests me the latter, but I may well be wrong!)
I definitely mean a file that is exclusively locked by the running
process. The file never goes out of existence. If you will, it
(not its contents) is part of the program as much as the executable.
Creation of a "flag file" at startup has the one disadvantage that
there is no safe way to remove the lock when the process ends (there's
always "kill -9" to break a scheme).
> Also, as I said in the other post, in this particular case the program
> is started ~/bin/. I can resonably imagine writing "similar" scripts
> to be installed "system-wide", but then I'd probably allow one
> instance per user per machine, so I'd simply stick with either using a
> per HOME lockfile or a /tmp per-user lockfile (as I've seen other
> programs doing).
If your aim is to protect users from accidentally running the
program twice, that should be fine, provided you have a procedure
to remove all outstanding lock files at system startup.
If you are fighting a mix of ignorant and malicious users, you'll
have to do more.
Anno
------------------------------
Date: Fri, 15 Oct 2004 07:32:26 +0200
From: "un" <usenet@root.mailshell.com>
Subject: Re: setting cookies (mod_perl)
Message-Id: <416f60ea$1@news.broadpark.no>
That worked! I thought I'd tried that one already... Anyway, thanks a lot!
------------------------------
Date: Thu, 14 Oct 2004 19:46:39 -0500
From: Tad McClellan <tadmc@augustmail.com>
Subject: Re: String and Array Programming in Perl
Message-Id: <slrncmu7ff.59s.tadmc@magna.augustmail.com>
Whitey Johnson <whitey@newmail.net> wrote:
> On Thu, 14 Oct 2004 10:28:26 -0700, DeveloperGuy muttered incoherently:
>> open(DataFileHandle, "/home/smallp/data.txt");
>> @tmpfile = <DataFileHandle>;
>> foreach $i (@tmpfile)
>> {
>> print "$i\n";
> my @pslist = `ps -aux`;
> foreach (@pslist) {
> That way you don't have to worry about running ps from the command line
> you can get a new output from it everytime you run your script.
You don't need the @pslist temporary variable either:
foreach ( `ps -aux` ) {
--
Tad McClellan SGML consulting
tadmc@augustmail.com Perl programming
Fort Worth, Texas
------------------------------
Date: Thu, 14 Oct 2004 19:51:05 -0500
From: Tad McClellan <tadmc@augustmail.com>
Subject: Re: String and Array Programming in Perl
Message-Id: <slrncmu7np.59s.tadmc@magna.augustmail.com>
DeveloperGuy <Phillip.Small@gmail.com> wrote:
> I have looked in the online sections you have recommended but what is
> wrong with the script?
It is not written in the Perl programming language, for a start.
> open PS, "data.txt" or die "could not open file $!";
> foreach $i (<data.txt>) {
^^^^^^^^
That is not a filehandle, you need a filehandle for the input operator.
> if @tmpline[0] != @users
Perl requires parenthesis around the condition.
Since your code does not have any parenthesis around the condition,
it is not written in Perl.
We cannot help troubleshoot code in other languages.
Sorry.
[ snip 140 lines that didn't need to be there.
DO NOT TOP-POST!
Find out what that is and how to not do it.
Top-post one more time and all of your posts will become
invisible to me forevermore.
]
--
Tad McClellan SGML consulting
tadmc@augustmail.com Perl programming
Fort Worth, Texas
------------------------------
Date: Thu, 14 Oct 2004 20:53:35 -0500
From: Tad McClellan <tadmc@augustmail.com>
Subject: Re: Top posting (was Re: Concatenating an array into one string?)
Message-Id: <slrncmubcv.59s.tadmc@magna.augustmail.com>
Charlton Wilbur <cwilbur@mithril.chromatico.net> wrote:
> comp.lang.perl.misc strongly prefers bottom-posting, and if you expect
> your posts to be read by people who have a clue, you would do well to
> bottom-post; consistent top-posting *will* get you added to scorefiles
> and killfiles. This is reinforced in the Posting Guidelines
The Posting Guidelines were derived from scorefiles.
I had several scorefiles from regulars who either posted them
or sent them in response to my email request.
When I found that people got killfiled for doing something, I put
a "don't do something" bullet in the guidelines.
After working through them all, the guidelines had been written.
:-)
> you may also note that people who
> top-post out of ignorance are treated far more kindly than those who
> grow belligerent over it.
My most populous scoring category is "know-it-all whiners" who tell
us we've been doing it wrong all of these years and that we should
all switch to their way instead.
The 1st (top)post goes right by with no harm done, it is a 2nd whiney
post that saves my time, as I can just zap out a scorefile entry
and be done with it.
--
Tad McClellan SGML consulting
tadmc@augustmail.com Perl programming
Fort Worth, Texas
------------------------------
Date: Thu, 14 Oct 2004 21:01:20 -0500
From: Tad McClellan <tadmc@augustmail.com>
Subject: Re: Top posting (was Re: Concatenating an array into one string?)
Message-Id: <slrncmubrg.59s.tadmc@magna.augustmail.com>
Shawn Corey <shawn.corey@sympatico.ca> wrote:
> Tad McClellan wrote:
>>>Personally, I like top-posting
>>
>>
>> So long then.
>
> That's what I was saying all along:
At this point I have a vanishingly small interest in what you say.
> if you can't tolerate people being
> people, don't read newsgroups.
If you can't tolerate people being people, don't go to Disneyland.
In article <1995Nov9.193745.13694@netlabs.com>, lwall@netlabs.com
(Larry Wall) wrote: ...
[snip] I view a programming language as a place to be
explored, like Disneyland. You don't need to have a lot of preparation
to explore a theme park. You do have to go along with the crowd
control measures, though. In a sense, each ride has its own
prerequisites--if you cut in line, you risk getting tossed out of the
park.
What we have here in this newsgroup is a failure in crowd control.
Reading the FAQ is like staying in line--it's something you should
learn in kindergarten. Usenet needs a better kindergarten.
You can try arguing that the idea of waiting in lines is a bad idea,
but you are not likely to convert the way of the thousands to the
way of the one.
The numbers are just too overwhelming. It is futile.
Your only choices are to wait in lines, or to not go to places that
make you wait in lines.
--
Tad McClellan SGML consulting
tadmc@augustmail.com Perl programming
Fort Worth, Texas
------------------------------
Date: Thu, 14 Oct 2004 22:52:58 -0500
From: Tad McClellan <tadmc@augustmail.com>
Subject: Re: Top posting (was Re: Concatenating an array into one string?)
Message-Id: <slrncmuicq.59s.tadmc@magna.augustmail.com>
Richard S Beckett <spikeywan@bigfoot.com> wrote:
> "Sam Holden" <sholden@flexal.cs.usyd.edu.au> wrote
>
>> Most people consider it polite to inform new people about
>> actions which will, if they are repeated, cause possibly
>> unwanted harmful side effects - in this case a large chunk
>> of the most knowledgable posters not answering your questions.
>
> If only!
>
> I think you'll have to agree that being polite is a rare occurrence in this
> ng!
Yes, there is an endless supply of the top-posters that you
must be referring to.
The angst is a symptom, it is not the disease.
--
Tad McClellan SGML consulting
tadmc@augustmail.com Perl programming
Fort Worth, Texas
------------------------------
Date: 15 Oct 2004 09:52:18 +0200
From: Arndt Jonasson <do-not-use@invalid.net>
Subject: Re: Top posting (was Re: Concatenating an array into one string?)
Message-Id: <yzdekk0ju4t.fsf@invalid.net>
Michele Dondi <bik.mido@tiscalinet.it> writes:
> On 14 Oct 2004 13:59:32 +0200, Arndt Jonasson <do-not-use@invalid.net>
> wrote:
>
> >A: Because it messes up the order in which people normally read text.
> >Q: Why is top-posting such a bad thing?
> >A: Top-posting.
> >Q: What is the most annoying thing on usenet and in e-mail?
>
> Cool! I remember someone using this as his own .sig in some ng I
> follow...
Yes, that's where I got it - I don't know who wrote it.
------------------------------
Date: Fri, 15 Oct 2004 07:56:16 GMT
From: Bart Lateur <bart.lateur@pandora.be>
Subject: Re: undef takes forever
Message-Id: <a70vm0psbnt64tr8q3ffcos0e9t56p7660@4ax.com>
Anno Siegel wrote:
>From the Camel:
>
> It [END and DESTROY] isn't run if, instead of exiting, the current
> process just morphs itself from one program to another via exec.
>
>I can't find the equivalent passage in perldoc.
See the bottom of "perldoc -f exec":
Note that "exec" will not call your "END" blocks, nor will it
call any "DESTROY" methods in your objects.
I know of a person who used
exec("true");
as a way to quickly get out of a perl script. "true" is a Unix/BSD/Linux
command line "tool" that doesn't do much at all. (I think its main
purpose is to be used in "make" setups.)
man true: <http://www.rt.com/man/true.1.html>
--
Bart.
------------------------------
Date: Thu, 14 Oct 2004 21:11:39 -0400
From: "daniel kaplan" <nospam@nospam.com>
Subject: use CGI question
Message-Id: <1097802765.32067@nntp.acecape.com>
there is a way to say use CGI ----
where the --- makes all errros/dies go to the browser...i cnat find it in my
book tho....
please help
------------------------------
Date: Fri, 15 Oct 2004 00:42:41 -0500
From: Tony Curtis <tony_curtis32@yahoo.com>
Subject: Re: use CGI question
Message-Id: <87k6ts8rla.fsf@limey.hpcc.uh.edu>
>> On Thu, 14 Oct 2004 21:11:39 -0400,
>> "daniel kaplan" <nospam@nospam.com> said:
> there is a way to say use CGI ---- where the --- makes all
> errros/dies go to the browser...i cnat find it in my book
> tho....
CGI::Carp
hth
t
------------------------------
Date: Fri, 15 Oct 2004 15:47:20 +1000
From: Gregory Toomey <nospam@bigpond.com>
Subject: Re: use CGI question
Message-Id: <2t96j8F1t4e68U1@uni-berlin.de>
daniel kaplan wrote:
> there is a way to say use CGI ----
>
> where the --- makes all errros/dies go to the browser...i cnat find it in
> my book tho....
>
> please help
use CGI::Carp qw(fatalsToBrowser);
gtoomey
------------------------------
Date: Fri, 15 Oct 2004 05:49:11 GMT
From: ced@bcstec.ca.boeing.com (Charles DeRykus)
Subject: Re: use CGI question
Message-Id: <I5M2tz.26L@news.boeing.com>
In article <1097802765.32067@nntp.acecape.com>,
daniel kaplan <nospam@nospam.com> wrote:
>there is a way to say use CGI ----
>
>where the --- makes all errros/dies go to the browser...i cnat find it in my
>book tho....
>
use CGI::Carp qw(fatalsToBrowser warningsToBrowser);
------------------------------
Date: 6 Apr 2001 21:33:47 GMT (Last modified)
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------------------------------
End of Perl-Users Digest V10 Issue 7254
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