[24436] in Perl-Users-Digest
Perl-Users Digest, Issue: 6620 Volume: 10
daemon@ATHENA.MIT.EDU (Perl-Users Digest)
Fri May 28 09:05:40 2004
Date: Fri, 28 May 2004 06:05:06 -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, 28 May 2004 Volume: 10 Number: 6620
Today's topics:
Re: Anonymous <usenet@morrow.me.uk>
Re: Anonymous <net.weathersongATnemo>
Re: Anonymous <rwxr-xr-x@gmx.de>
MyPAN? <vetro@online.no>
Re: MyPAN? <postmaster@castleamber.com>
Re: MyPAN? <vetro@online.no>
Re: MyPAN? <postmaster@castleamber.com>
Re: MyPAN? <vetro@online.no>
Re: Net::SCP::Expect problem (Magnus)
Re: On "for (@foo)" <atp5470 at fsu.edu>
Re: On "for (@foo)" <usenet@morrow.me.uk>
Re: On "for (@foo)" (Anno Siegel)
Re: On "for (@foo)" <postmaster@castleamber.com>
Re: On "for (@foo)" <please_post@nomail.edu>
Posting Guidelines for comp.lang.perl.misc ($Revision: tadmc@augustmail.com
Re: Remove first letter of each string in array <uri.guttman@fmr.com>
Unwanted double-interpolation in string passed to backt <lawshouse.public@btconnect.com>
Re: Unwanted double-interpolation in string passed to b (Anno Siegel)
Re: Unwanted double-interpolation in string passed to b <ittyspam@yahoo.com>
Re: Unwanted double-interpolation in string passed to b (Anno Siegel)
Re: Unwanted double-interpolation in string passed to b <ittyspam@yahoo.com>
Re: Why is this upload script not working <noreply@gunnar.cc>
Digest Administrivia (Last modified: 6 Apr 01) (Perl-Users-Digest Admin)
----------------------------------------------------------------------
Date: Fri, 28 May 2004 07:21:36 +0000 (UTC)
From: Ben Morrow <usenet@morrow.me.uk>
Subject: Re: Anonymous
Message-Id: <c96pa0$hlu$1@wisteria.csv.warwick.ac.uk>
Quoth David Frauzel <net.weathersongATnemo>:
> Ben Morrow <usenet@morrow.me.uk> wrote in
> news:c96214$a0f$1@wisteria.csv.warwick.ac.uk:
>
> Is this:
>
> ['foo', 'bar']
>
> An anonymous array, or a *reference* to an anonymous array? (Which is what
> I meant originally about anonymous arrays and references being
> inseperable.)
It returns a reference to one.
> I get the feeling now that there's no such thing as "just" an anonymous
> array, only references to them.
Well, yes... for the array to exist, it must *either* have at least one
name *or* at least one reference... Think about it. An anon array has no
name: how are you going to access it except through a reference?
> What I mean is:
>
> # Passes an array (as a list)
> &foo @bar;
> # Passes a list
> &foo +('foo', 'bar');
> # Passes a reference
> &foo ['foo', 'bar'];
Yup.
Two notes: don't call subs with & unless you know what it does and why
you need it, and you can just write
foo 'foo', 'bar';
rather than that +(...) business.
Ben
--
perl -e'print map {/.(.)/s} sort unpack "a2"x26, pack "N"x13,
qw/1632265075 1651865445 1685354798 1696626283 1752131169 1769237618
1801808488 1830841936 1886550130 1914728293 1936225377 1969451372
2047502190/' # ben@morrow.me.uk
------------------------------
Date: Fri, 28 May 2004 08:01:50 GMT
From: David Frauzel <net.weathersongATnemo>
Subject: Re: Anonymous
Message-Id: <23691bf037b468479369aa0d5bb03288@news.teranews.com>
Ben Morrow <usenet@morrow.me.uk> wrote in
news:c96pa0$hlu$1@wisteria.csv.warwick.ac.uk:
> Yup.
>
> Two notes: don't call subs with & unless you know what it does and why
> you need it, and you can just write
>
> foo 'foo', 'bar';
>
> rather than that +(...) business.
Just being overtly clear that those were subs, and just using +() to
indicate overtly that I meant a list (since foo may not have been a list
operator).
Thanks for the answers. :}
------------------------------
Date: 28 May 2004 12:02:13 GMT
From: Lukas Mai <rwxr-xr-x@gmx.de>
Subject: Re: Anonymous
Message-Id: <c979o5$30b$1@wsc10.lrz-muenchen.de>
David Frauzel schrob:
[...]
> What I mean is:
> # Passes an array (as a list)
> &foo @bar;
That's a syntax error:
Array found where operator expected at -e line 1, near "&foo "
> # Passes a list
> &foo +('foo', 'bar');
No. It's parsed as &foo + ('???', 'bar'), i.e. it calls foo with the
current @_ and adds 'bar' to the result.
> # Passes a reference
> &foo ['foo', 'bar'];
syntax error at -e line 1, near "&foo ["
foo(['foo', 'bar']) (or foo ['foo', 'bar'] if sub foo is predeclared) on
the other hand calls foo with a one-element list. That element is an
array reference.
Conclusion: Don't use & for sub calls unless you know *exactly* what
you're doing. And subs are always called with an argument list (which
may be empty or contain references).
> So "anonymous" doesn't just mean unnamed, it also implicates a reference?
> (But I get the idea they wouldn't be possible otherwise.)
Basically yes. You need either a name or a reference to use a variable.
Otherwise it's unreachable.
HTH, Lukas
--
#include <stdio.h>
static int r(int c,int d){return d && d < 27 ? 96 & c | 1 + (12+d) % 26 : c;}
static int o(int c){return c!=EOF ? putchar(r(c,64^c&223)),o(getchar()) : 0;}
int main(void){return o(getchar());}
------------------------------
Date: Fri, 28 May 2004 11:29:40 +0200
From: "Vetle Roeim" <vetro@online.no>
Subject: MyPAN?
Message-Id: <opr8pdzqvo3hk3cf@quickfix.opera.com>
Hi folks. CPAN is really great. It is in fact so great, that we'd really
like to set up our own CPAN-ish server where I work, to make it easier to
distribute and install our own modules.
I searched a little around on the web for some information on how to do
this (it is possible, right?), but didn't find much. I found CPAN::Site,
but it hasn't been updated since 1999, and the current version is 0.014.
Has anyone used this successfully? Should I try using it?
Any pointers on how to do this?
Is it a good idea, or should we just forget about the whole thing?
--
Touch eyeballs to screen for cheap laser surgery!
------------------------------
Date: Fri, 28 May 2004 04:34:25 -0500
From: John Bokma <postmaster@castleamber.com>
Subject: Re: MyPAN?
Message-Id: <40b707a3$0$208$58c7af7e@news.kabelfoon.nl>
Vetle Roeim wrote:
> Hi folks. CPAN is really great. It is in fact so great, that we'd really
> like to set up our own CPAN-ish server where I work, to make it easier to
> distribute and install our own modules.
LAN? Or the Internet? In the latter case, why not contribute them to CPAN?
--
John MexIT: http://johnbokma.com/mexit/
personal page: http://johnbokma.com/
Experienced Perl programmer available: http://castleamber.com/
------------------------------
Date: Fri, 28 May 2004 11:41:18 +0200
From: "Vetle Roeim" <vetro@online.no>
Subject: Re: MyPAN?
Message-Id: <opr8pei4pn3hk3cf@quickfix.opera.com>
On Fri, 28 May 2004 04:34:25 -0500, John Bokma
<postmaster@castleamber.com> wrote:
> Vetle Roeim wrote:
>
>> Hi folks. CPAN is really great. It is in fact so great, that we'd
>> really
>> like to set up our own CPAN-ish server where I work, to make it
>> easier to
>> distribute and install our own modules.
>
> LAN?
Yep.
> Or the Internet? In the latter case, why not contribute them to CPAN?
Although I'm a big supporter of open source software, I'm not in
a position to decide if the code I create can be distributed with
an open source license because my employer holds the copyright to
the code I create.
--
Touch eyeballs to screen for cheap laser surgery!
------------------------------
Date: Fri, 28 May 2004 05:20:33 -0500
From: John Bokma <postmaster@castleamber.com>
Subject: Re: MyPAN?
Message-Id: <40b71272$0$215$58c7af7e@news.kabelfoon.nl>
Vetle Roeim wrote:
> Although I'm a big supporter of open source software, I'm not in
> a position to decide if the code I create can be distributed with
> an open source license because my employer holds the copyright to
> the code I create.
Ask :-D. When the modules are used by more people, they are tested by
more people and improved (often) :-D. Unless they contain very sensitive
stuff, of course.
--
John MexIT: http://johnbokma.com/mexit/
personal page: http://johnbokma.com/
Experienced Perl programmer available: http://castleamber.com/
------------------------------
Date: Fri, 28 May 2004 12:38:19 +0200
From: "Vetle Roeim" <vetro@online.no>
Subject: Re: MyPAN?
Message-Id: <opr8pg55qa3hk3cf@quickfix.opera.com>
On Fri, 28 May 2004 05:20:33 -0500, John Bokma
<postmaster@castleamber.com> wrote:
> Vetle Roeim wrote:
>
>> Although I'm a big supporter of open source software, I'm not in
>> a position to decide if the code I create can be distributed with
>> an open source license because my employer holds the copyright to
>> the code I create.
>
> Ask :-D.
Of course. :) Releasing them under an open source license is a very
real possibility, but it's not a priority right now.
> When the modules are used by more people, they are tested by more people
> and improved (often) :-D.
Indeed, but as long as we don't have the option of submitting all our
modules to CPAN, we'd like to have the option of having a local
CPAN-ish server if it's possible.
[...]
--
Touch eyeballs to screen for cheap laser surgery!
------------------------------
Date: 28 May 2004 05:34:00 -0700
From: mapal@home.se (Magnus)
Subject: Re: Net::SCP::Expect problem
Message-Id: <f2463108.0405280434.31088505@posting.google.com>
Everything works okey now, but I would like to know if there is any way
to get the progress meter to function whitin net::scp::expect?
Thanks.
mapal@home.se (Magnus) wrote in message news:<f2463108.0405140145.5002f92c@posting.google.com>...
> Hi,
> I´m having problems with Net::SCP::Expect.
>
> My script looks like this:
>
> my $scpe = Net::SCP::Expect->new(user=>'$username',password=>'$password',
> preserve=>1, recursive=>1, verbose=>1);
> $scpe->scp('$host:/home/foo/','/destination');
>
> If I run this script as root the scripts try to connect as root, not
> as the user I´ve set in $username. If I run the script as the same
> user as $username
> it will be correct but it ask for password. The password is correct,
> when I run a manual scp and enter the same password it works...
>
> I´m running slackware 9.1 on both servers and using OpenSSH_3.7.1p2
> and OpenSSH_3.8p1.
>
> What can be wrong?
>
> Thanks.
>
> Regards,
> Magnus
------------------------------
Date: Fri, 28 May 2004 03:27:46 -0500
From: "Andrew Palmer" <atp5470 at fsu.edu>
Subject: Re: On "for (@foo)"
Message-Id: <10bdtt5cac7bocf@corp.supernews.com>
> OK, now, in an expression like this
>
> for my $x (@X) {
> # etc.
> }
>
> I assume that Perl keeps track of the index on @X correponding to
> the current element. Is there a way to access this "current index"
> from within a Perl program?
I think the only way to do what you want is like
for(my $i=0;$i<$#X;++$i)
{
$X[$i]=0;
}
------------------------------
Date: Fri, 28 May 2004 09:09:46 +0000 (UTC)
From: Ben Morrow <usenet@morrow.me.uk>
Subject: Re: On "for (@foo)"
Message-Id: <c96vkq$kkk$1@wisteria.csv.warwick.ac.uk>
Quoth "Andrew Palmer" <atp5470 at fsu.edu>:
> > OK, now, in an expression like this
> >
> > for my $x (@X) {
> > # etc.
> > }
> >
> > I assume that Perl keeps track of the index on @X correponding to
> > the current element. Is there a way to access this "current index"
> > from within a Perl program?
>
> I think the only way to do what you want is like
>
> for(my $i=0;$i<$#X;++$i)
> {
> $X[$i]=0;
> }
You never need C-style loops:
for my $i (0..$#X) {
$X[$i] = 0;
}
Ben
--
We do not stop playing because we grow old;
we grow old because we stop playing.
ben@morrow.me.uk
------------------------------
Date: 28 May 2004 09:25:48 GMT
From: anno4000@lublin.zrz.tu-berlin.de (Anno Siegel)
Subject: Re: On "for (@foo)"
Message-Id: <c970is$afo$1@mamenchi.zrz.TU-Berlin.DE>
Ben Morrow <usenet@morrow.me.uk> wrote in comp.lang.perl.misc:
>
> Quoth "Andrew Palmer" <atp5470 at fsu.edu>:
> > > OK, now, in an expression like this
> > >
> > > for my $x (@X) {
> > > # etc.
> > > }
> > >
> > > I assume that Perl keeps track of the index on @X correponding to
> > > the current element. Is there a way to access this "current index"
> > > from within a Perl program?
> >
> > I think the only way to do what you want is like
> >
> > for(my $i=0;$i<$#X;++$i)
> > {
> > $X[$i]=0;
> > }
>
> You never need C-style loops:
>
> for my $i (0..$#X) {
> $X[$i] = 0;
> }
$_ = 0 for @X;
Anno
------------------------------
Date: Fri, 28 May 2004 04:28:48 -0500
From: John Bokma <postmaster@castleamber.com>
Subject: Re: On "for (@foo)"
Message-Id: <40b70654$0$208$58c7af7e@news.kabelfoon.nl>
Anno Siegel wrote:
> $_ = 0 for @X;
@X = (0) x @X;
--
John MexIT: http://johnbokma.com/mexit/
personal page: http://johnbokma.com/
Experienced Perl programmer available: http://castleamber.com/
------------------------------
Date: Fri, 28 May 2004 12:47:24 +0000 (UTC)
From: bill <please_post@nomail.edu>
Subject: Re: On "for (@foo)"
Message-Id: <c97ccs$hj5$1@reader2.panix.com>
In <c966vt$bkc$1@wisteria.csv.warwick.ac.uk> Ben Morrow <usenet@morrow.me.uk> writes:
>Quoth bill <please_post@nomail.edu>:
>> Surprisingly, to me at least, this doesn't produce any errors:
>>
>> for my $y (1..3) {
>> $y = 0;
>> }
>>
>> Perl doesn't see the above as analogous to
>>
>> 1 = 0; # triggers "Can't modify constant item" error
>No: an array element is an lvalue, and modifiable.
Ah, yes. Somehow I thought that '..' returned a list. Come to
think of it, does anything in Perl *ever* return a list? I tried
other things that I *thought* returned lists, such as `command` or
m//g, in expressions like
for my $x (`seq 1 3`) {
$x = 0;
}
or
for my $x ('123' =~ m/\d/g) {
$x = 0;
}
but Perl did not complain, unlike the case
for my $x (1, 2, 3) {
$x = 0;
}
in which Perl kicks up a ruckus.
Then again, maybe this is not a terribly good test of listudinosity.
-bill
------------------------------
Date: Fri, 28 May 2004 02:23:43 -0500
From: tadmc@augustmail.com
Subject: Posting Guidelines for comp.lang.perl.misc ($Revision: 1.5 $)
Message-Id: <ztCdnTuXSr9idSvd4p2dnA@august.net>
Outline
Before posting to comp.lang.perl.misc
Must
- Check the Perl Frequently Asked Questions (FAQ)
- Check the other standard Perl docs (*.pod)
Really Really Should
- Lurk for a while before posting
- Search a Usenet archive
If You Like
- Check Other Resources
Posting to comp.lang.perl.misc
Is there a better place to ask your question?
- Question should be about Perl, not about the application area
How to participate (post) in the clpmisc community
- Carefully choose the contents of your Subject header
- Use an effective followup style
- Speak Perl rather than English, when possible
- Ask perl to help you
- Do not re-type Perl code
- Provide enough information
- Do not provide too much information
- Do not post binaries, HTML, or MIME
Social faux pas to avoid
- Asking a Frequently Asked Question
- Asking a question easily answered by a cursory doc search
- Asking for emailed answers
- Beware of saying "doesn't work"
- Sending a "stealth" Cc copy
Be extra cautious when you get upset
- Count to ten before composing a followup when you are upset
- Count to ten after composing and before posting when you are upset
-----------------------------------------------------------------
Posting Guidelines for comp.lang.perl.misc ($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: 27 May 2004 13:14:37 -0400
From: Uri Guttman <uri.guttman@fmr.com>
Subject: Re: Remove first letter of each string in array
Message-Id: <liekp5rdvm.fsf@localhost.localdomain>
>>>>> "BM" == Brian McCauley <nobull@mail.com> writes:
BM> However, it's not so fast...
you chose a bad data set for this.
BM> use Benchmark;
BM> my @data = ( 'aaa' ... 'zzz' );
those strings are too short. the copy is quick and so it looks like it
beats the 4 arg substr. try this data:
my @data = ( 'a' x 1000 ) x 1000 ;
Benchmark: running map, substr1, substr2, substr3 for at least 2 CPU seconds...
map: 2 wallclock secs ( 2.22 usr + 0.00 sys = 2.22 CPU) @ 127.48/s (n=283)
substr1: 2 wallclock secs ( 2.18 usr + 0.00 sys = 2.18 CPU) @ 293.12/s (n=639)
substr2: 2 wallclock secs ( 2.07 usr + 0.00 sys = 2.07 CPU) @ 347.34/s (n=719)
substr3: 2 wallclock secs ( 2.05 usr + 0.00 sys = 2.05 CPU) @ 317.07/s (n=650)
now 4 arg substr is much faster.
this is why benchmarking is an art unto itself. it is so easy to get
results that support wrong conclusions.
uri
------------------------------
Date: Fri, 28 May 2004 11:30:47 +0100
From: Henry Law <lawshouse.public@btconnect.com>
Subject: Unwanted double-interpolation in string passed to backticks
Message-Id: <kd4eb0h5mh0l3d5otckh65au2u9qro2ep0@4ax.com>
I think I've done my homework on this, including "How can I call
backticks without shell processing?" in perlfaq8, and a Groups search
on "perl shell escape characters backticks" but I'm none the wiser;
pointers would be welcome.
Here's a test program:
-----------------------
#! /usr/bin/perl
use strict;
use warnings;
print "Enter filename:";
my $filename = <STDIN>;
chomp $filename;
my $ret = `ls -m $filename`;
print "Returned value:$ret\n";
-----------------------
The problem comes when the file name that is entered contains the "$"
character, which in my case it often does. In the test directory
there is a file called "test" and another called "$test". If I run
the program above and enter "test" the result is as expected, thus:
$ ./test
Enter filename:test
Returned value:test
But if I enter the name of the "$test" file, the variable $filename is
interpolated a second time, and since there is no "$test" variable
within the program it comes out as null, thus:
$ ./test
Enter filename:$test
Returned value:bashref.html, c, d, (etc.. the whole directory)
Escaping the $ within the backticks won't work, since I do want Perl
to interpolate $filename, so what to do? My current work-round is a
sub called "shell_execute" which takes the string to be executed
(after one level of interpolation) and then escapes the dollar signs
before running backticks. It works, but ITNABWTDI?
Henry Law <>< Manchester, England
------------------------------
Date: 28 May 2004 10:57:29 GMT
From: anno4000@lublin.zrz.tu-berlin.de (Anno Siegel)
Subject: Re: Unwanted double-interpolation in string passed to backticks
Message-Id: <c975up$gs6$1@mamenchi.zrz.TU-Berlin.DE>
Henry Law <news@lawshouse.org> wrote in comp.lang.perl.misc:
> I think I've done my homework on this, including "How can I call
> backticks without shell processing?" in perlfaq8, and a Groups search
> on "perl shell escape characters backticks" but I'm none the wiser;
> pointers would be welcome.
>
> Here's a test program:
> -----------------------
> #! /usr/bin/perl
>
> use strict;
> use warnings;
>
> print "Enter filename:";
> my $filename = <STDIN>;
> chomp $filename;
>
> my $ret = `ls -m $filename`;
>
> print "Returned value:$ret\n";
> -----------------------
>
> The problem comes when the file name that is entered contains the "$"
> character, which in my case it often does. In the test directory
> there is a file called "test" and another called "$test". If I run
> the program above and enter "test" the result is as expected, thus:
>
> $ ./test
> Enter filename:test
> Returned value:test
>
> But if I enter the name of the "$test" file, the variable $filename is
> interpolated a second time, and since there is no "$test" variable
> within the program it comes out as null, thus:
>
> $ ./test
> Enter filename:$test
> Returned value:bashref.html, c, d, (etc.. the whole directory)
The unwanted interpolation happens in the shell that is called to
execute "ls". To avoid this, escape the dollar:
$filename =~ s'\$'\\$'g;
Anno
------------------------------
Date: Fri, 28 May 2004 08:15:52 -0400
From: Paul Lalli <ittyspam@yahoo.com>
Subject: Re: Unwanted double-interpolation in string passed to backticks
Message-Id: <20040528080930.J18263@dishwasher.cs.rpi.edu>
On Fri, 28 May 2004, Henry Law wrote:
> Here's a test program:
> -----------------------
> #! /usr/bin/perl
>
> use strict;
> use warnings;
>
> print "Enter filename:";
> my $filename = <STDIN>;
> chomp $filename;
>
> my $ret = `ls -m $filename`;
>
> print "Returned value:$ret\n";
> -----------------------
>
> The problem comes when the file name that is entered contains the "$"
> character, which in my case it often does. In the test directory
> there is a file called "test" and another called "$test". If I run
> the program above and enter "test" the result is as expected, thus:
>
> $ ./test
> Enter filename:test
> Returned value:test
>
> But if I enter the name of the "$test" file, the variable $filename is
> interpolated a second time, and since there is no "$test" variable
> within the program it comes out as null, thus:
>
> $ ./test
> Enter filename:$test
> Returned value:bashref.html, c, d, (etc.. the whole directory)
Perl is not interpolating your variable a second time. The shell is
interpolating the variable $test. To verify, try entering the command in
your shell, without perl:
ls -m $test
You will see the same results, that is, an entire directory listing. In
the shell, you'd have to do:
ls -m \$test
which should give you the clue of how to solve this. You could search and
replace all 'special' characters to have a backslash precede them.
However, Perl gives you a way to do this:
$return = `ls -m \Q$filename\E`;
or
$filename = quotemeta $filename
$return = `ls -m $filename`;
Read about quotemeta in perldoc -f quotemeta, and \Q in perldoc perlop
under "Quote and Quote-like Operators"
Paul Lalli
------------------------------
Date: 28 May 2004 12:28:03 GMT
From: anno4000@lublin.zrz.tu-berlin.de (Anno Siegel)
Subject: Re: Unwanted double-interpolation in string passed to backticks
Message-Id: <c97b8j$kde$1@mamenchi.zrz.TU-Berlin.DE>
Paul Lalli <ittyspam@yahoo.com> wrote in comp.lang.perl.misc:
> On Fri, 28 May 2004, Henry Law wrote:
>
> > Here's a test program:
> > -----------------------
> > #! /usr/bin/perl
> >
> > use strict;
> > use warnings;
> >
> > print "Enter filename:";
> > my $filename = <STDIN>;
> > chomp $filename;
> >
> > my $ret = `ls -m $filename`;
> >
> > print "Returned value:$ret\n";
> > -----------------------
[...]
> However, Perl gives you a way to do this:
>
> $return = `ls -m \Q$filename\E`;
> or
> $filename = quotemeta $filename
> $return = `ls -m $filename`;
>
> Read about quotemeta in perldoc -f quotemeta, and \Q in perldoc perlop
> under "Quote and Quote-like Operators"
With quotemeta() you'll also escape "/", which is unwanted in file
names.
Anno
------------------------------
Date: Fri, 28 May 2004 08:41:51 -0400
From: Paul Lalli <ittyspam@yahoo.com>
Subject: Re: Unwanted double-interpolation in string passed to backticks
Message-Id: <20040528084020.I18263@dishwasher.cs.rpi.edu>
On Fri, 28 May 2004, Anno Siegel wrote:
> > However, Perl gives you a way to do this:
> >
> > $return = `ls -m \Q$filename\E`;
> > or
> > $filename = quotemeta $filename
> > $return = `ls -m $filename`;
> >
> > Read about quotemeta in perldoc -f quotemeta, and \Q in perldoc perlop
> > under "Quote and Quote-like Operators"
>
> With quotemeta() you'll also escape "/", which is unwanted in file
> names.
Unneeded, perhaps. But it has no ill effect, at least not with the shell
I'm using (I believe it's bash).
ls -al foo\/bar
has the same effect as
ls -al foo/bar
Are there shells out there that would throw an error at this?
Paul Lalli
------------------------------
Date: Fri, 28 May 2004 11:11:44 +0200
From: Gunnar Hjalmarsson <noreply@gunnar.cc>
Subject: Re: Why is this upload script not working
Message-Id: <2hoe87Fev8qaU2@uni-berlin.de>
Mark Constant wrote:
> Here are the most important parts.
What does the form look like? That's also important. :)
--
Gunnar Hjalmarsson
Email: http://www.gunnar.cc/cgi-bin/contact.pl
------------------------------
Date: 6 Apr 2001 21:33:47 GMT (Last modified)
From: Perl-Users-Request@ruby.oce.orst.edu (Perl-Users-Digest Admin)
Subject: Digest Administrivia (Last modified: 6 Apr 01)
Message-Id: <null>
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------------------------------
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