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This queue is for tickets about the IPC-System-Simple CPAN distribution.

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The Basics
Id: 44731
Status: resolved
Priority: 0/
Queue: IPC-System-Simple
People
Owner: PJF [...] cpan.org
Requestors: sobek [...] irit.fr
Cc:
AdminCc:
Bug Information
Severity: (no value)
Broken in: 1.18
Fixed in: (no value)

History Show all quoted text
  Wed Apr 01 13:04:01 2009 sobek [...] irit.fr - Ticket created
Subject: a bug in IPC-System-Simple
My problem is that I cannot inhibit variable interpolation, etc. under capturex, under IPC-System-Simple-1.18! I call the following line: my @lines = eval(capturex(EXIT_ANY, "$GREP", $mid , @FILES)); where $GREP is the path to grep, @FILES are the files to check, and $mid is a pattern containing a message-id mail header. It is $mid that does not pass! Either I quotemeta() protect it fully, and the pattern is not found by grep, or capturex producees a stack dump about "Possible unintended interpolation of ...". Here is the correct pattern for grep: ^Message-[Ii][Dd]: *<4A233B7B98624E2C8039746A8A06D1D9\@KarenPC> The anti-slash, \, is not necessary for grep. The system perl function does not have this problem! The error messages are appended at the end! perl -v: This is perl, v5.8.0 built for sun4-solaris uname -a: SunOS sareena 5.8 Generic_108528-19 sun4u sparc SUNW,Sun-Blade-100 Error messages: Possible unintended interpolation of @KarenPC in string at (eval 16)[/ home/sobek/bin/compare-mail-folders:148] line 1. eval 'surnames.family.08-31:Message-ID: <4A233B7B98624E2C8039746A8A06D1D9@KarenPC> surnames.family.08-31:Message-ID: <4A233B7B98624E2C8039746A8A06D1D9@KarenPC> surnames.family.08-31:Message-ID: <4A233B7B98624E2C8039746A8A06D1D9@KarenPC> ;' called at /home/sobek/bin/compare-mail-folders line 148 main::chk_msg_id('4A233B7B98624E2C8039746A8A06D1D9@KarenPC') called at /home/sobek/bin/compare-mail-folders line 91 Bareword found where operator expected at (eval 16)[/home/sobek/bin/ compare-mail-folders:148] line 2, near "<4A233B7B98624E2C8039746A8A06D1D9@KarenPC> surnames" eval 'surnames.family.08-31:Message-ID: <4A233B7B98624E2C8039746A8A06D1D9@KarenPC> surnames.family.08-31:Message-ID: <4A233B7B98624E2C8039746A8A06D1D9@KarenPC> surnames.family.08-31:Message-ID: <4A233B7B98624E2C8039746A8A06D1D9@KarenPC> ;' called at /home/sobek/bin/compare-mail-folders line 148 main::chk_msg_id('4A233B7B98624E2C8039746A8A06D1D9@KarenPC') called at /home/sobek/bin/compare-mail-folders line 91 (Missing operator before surnames?) eval 'surnames.family.08-31:Message-ID: <4A233B7B98624E2C8039746A8A06D1D9@KarenPC> surnames.family.08-31:Message-ID: <4A233B7B98624E2C8039746A8A06D1D9@KarenPC> surnames.family.08-31:Message-ID: <4A233B7B98624E2C8039746A8A06D1D9@KarenPC> ;' called at /home/sobek/bin/compare-mail-folders line 148 main::chk_msg_id('4A233B7B98624E2C8039746A8A06D1D9@KarenPC') called at /home/sobek/bin/compare-mail-folders line 91 Possible unintended interpolation of @KarenPC in string at (eval 16)[/ home/sobek/bin/compare-mail-folders:148] line 2. eval 'surnames.family.08-31:Message-ID: <4A233B7B98624E2C8039746A8A06D1D9@KarenPC> surnames.family.08-31:Message-ID: <4A233B7B98624E2C8039746A8A06D1D9@KarenPC> surnames.family.08-31:Message-ID: <4A233B7B98624E2C8039746A8A06D1D9@KarenPC> ;' called at /home/sobek/bin/compare-mail-folders line 148 main::chk_msg_id('4A233B7B98624E2C8039746A8A06D1D9@KarenPC') called at /home/sobek/bin/compare-mail-folders line 91 Bareword found where operator expected at (eval 16)[/home/sobek/bin/ compare-mail-folders:148] line 3, near "<4A233B7B98624E2C8039746A8A06D1D9@KarenPC> surnames" eval 'surnames.family.08-31:Message-ID: <4A233B7B98624E2C8039746A8A06D1D9@KarenPC> surnames.family.08-31:Message-ID: <4A233B7B98624E2C8039746A8A06D1D9@KarenPC> surnames.family.08-31:Message-ID: <4A233B7B98624E2C8039746A8A06D1D9@KarenPC> ;' called at /home/sobek/bin/compare-mail-folders line 148 main::chk_msg_id('4A233B7B98624E2C8039746A8A06D1D9@KarenPC') called at /home/sobek/bin/compare-mail-folders line 91 (Missing operator before surnames?) eval 'surnames.family.08-31:Message-ID: <4A233B7B98624E2C8039746A8A06D1D9@KarenPC> surnames.family.08-31:Message-ID: <4A233B7B98624E2C8039746A8A06D1D9@KarenPC> surnames.family.08-31:Message-ID: <4A233B7B98624E2C8039746A8A06D1D9@KarenPC> ;' called at /home/sobek/bin/compare-mail-folders line 148 main::chk_msg_id('4A233B7B98624E2C8039746A8A06D1D9@KarenPC') called at /home/sobek/bin/compare-mail-folders line 91 Possible unintended interpolation of @KarenPC in string at (eval 16)[/ home/sobek/bin/compare-mail-folders:148] line 3. eval 'surnames.family.08-31:Message-ID: <4A233B7B98624E2C8039746A8A06D1D9@KarenPC> surnames.family.08-31:Message-ID: <4A233B7B98624E2C8039746A8A06D1D9@KarenPC> surnames.family.08-31:Message-ID: <4A233B7B98624E2C8039746A8A06D1D9@KarenPC> ;' called at /home/sobek/bin/compare-mail-folders line 148 main::chk_msg_id('4A233B7B98624E2C8039746A8A06D1D9@KarenPC') called at /home/sobek/bin/compare-mail-folders line 91 Error abort = Illegal octal digit '8' at (eval 16)[/home/sobek/bin/ compare-mail-folders:148] line 1, at end of line syntax error at (eval 16)[/home/sobek/bin/compare-mail-folders:148] line 1, near "31:" Global symbol "@KarenPC" requires explicit package name at (eval 16)[/ home/sobek/bin/compare-mail-folders:148] line 1. Illegal octal digit '8' at (eval 16)[/home/sobek/bin/compare-mail- folders:148] line 2, at end of line Global symbol "@KarenPC" requires explicit package name at (eval 16)[/ home/sobek/bin/compare-mail-folders:148] line 2. Illegal octal digit '8' at (eval 16)[/home/sobek/bin/compare-mail- folders:148] line 3, at end of line Global symbol "@KarenPC" requires explicit package name at (eval 16)[/ home/sobek/bin/compare-mail-folders:148] line 3. The lines listed as: surnames.family.08-31:Message-ID: <4A233B7B98624E2C8039746A8A06D1D9@KarenPC> are the 3 $result lines of the grep function. The $result does NOT make it through! Sincerely, --Ralph Sobek
  Thu Apr 02 07:08:24 2009 PJF [...] cpan.org - Taken
  Thu Apr 02 07:14:01 2009 PJF [...] cpan.org - Correspondence added
Subject: Unintended interpolation of variables in capturex()
G'day Ralph, I'm going to apologise for my short response, I'm currently interstate and using a free internet service provided by a bus-stop as my connection. On Wed Apr 01 13:04:01 2009, sobek@irit.fr wrote: Show quoted text
> my @lines = eval(capturex(EXIT_ANY, "$GREP", $mid , @FILES));
I'm a little perplexed what the 'eval' is doing here. 'eval' in this context is a string eval, which tells perl to interpret its arguments as perl code and execute them. Unless your files contain actual perl code you wish to evaluate, I would have expected your line to be: my @lines = capturex(EXIT_ANY, $GREP, $mid, @FILES); If the eval has another purpose, I can't fathom it, and would appreciate a further explanation. If the eval is there mistakenly, is there any chance you could remove it and tell me if the problem still persists? Many thanks, Paul
  Thu Apr 02 07:14:03 2009 The RT System itself - Status changed from 'new' to 'open'
  Thu Apr 02 07:14:24 2009 PJF [...] cpan.org - Subject changed from 'a bug in IPC-System-Simple' to 'Unintended interpolation of variables in capturex()'
  Thu Apr 02 07:14:24 2009 PJF [...] cpan.org - Severity Critical deleted
  Mon Apr 06 14:08:25 2009 sobek [...] irit.fr - Correspondence added
Subject: Re: [rt.cpan.org #44731] Unintended interpolation of variables in capturex()
Date: Mon, 6 Apr 2009 20:07:38 +0200
To: bug-IPC-System-Simple [...] rt.cpan.org
From: Ralph SOBEK <sobek [...] irit.fr>
Hi Paul, You are absolutely right! But the code was suggested in the man page section in order to protect from exceptions within the code: eval { run("cat *.txt"); }; if ($@) { print "Something went wrong - $@\n"; } As such, is it possible to protect from exceptions here? Thanks for your answer, --Ralph Show quoted text
>>>>> "PvR" == PJF via RT <bug-IPC-System-Simple@rt.cpan.org> writes:
Show quoted text
PvR> <URL: https://rt.cpan.org/Ticket/Display.html?id=44731 > PvR> G'day Ralph,
Show quoted text
PvR> I'm going to apologise for my short response, I'm currently interstate PvR> and using a free internet service provided by a bus-stop as my connection.
Show quoted text
PvR> On Wed Apr 01 13:04:01 2009, sobek@irit.fr wrote:
Show quoted text
>> my @lines = eval(capturex(EXIT_ANY, "$GREP", $mid , @FILES));
Show quoted text
PvR> I'm a little perplexed what the 'eval' is doing here. 'eval' in this PvR> context is a string eval, which tells perl to interpret its arguments as PvR> perl code and execute them.
Show quoted text
PvR> Unless your files contain actual perl code you wish to evaluate, I would PvR> have expected your line to be:
Show quoted text
PvR> my @lines = capturex(EXIT_ANY, $GREP, $mid, @FILES);
Show quoted text
PvR> If the eval has another purpose, I can't fathom it, and would appreciate PvR> a further explanation. If the eval is there mistakenly, is there any PvR> chance you could remove it and tell me if the problem still persists?
Show quoted text
PvR> Many thanks,
Show quoted text
PvR> Paul
  Mon Apr 06 19:11:38 2009 PJF [...] cpan.org - Correspondence added
G'day Ralph, On Mon Apr 06 14:08:25 2009, sobek@irit.fr wrote: Show quoted text
> You are absolutely right! But the code was suggested in the man > page > section in order to protect from exceptions within the code:
Aha! You've discovered the difference between eval(), which does a "string eval", and eval {}, which does a "block eval". The first considers its argument to be a string of Perl code, and evaluates it. It's almost never something you want. The second acts just like a "try" block in other languages. So, for your example, you should be able to use: my @lines = eval { capturex(EXIT_ANY, $GREP, $mid, @FILES); }; if ($@) { print "Oh noes! Something went wrong!\n"; } It's unfortunate that Perl has two different forms of 'eval'. If you use the Error module[1] from the CPAN, you can actually write 'try {}' instead of 'eval {}'. Likewise, if you're using Perl::Critic[2], it will complain loudly if it ever sees you using a string eval (since it's almost never needed). All the very best, Paul [1] http://search.cpan.org/search?query=Error [2] http://search.cpan.org/perldoc?perlcritic
  Mon Apr 06 19:11:42 2009 PJF [...] cpan.org - Status changed from 'open' to 'resolved'
  Thu Apr 09 14:28:45 2009 sobek [...] irit.fr - Correspondence added
Subject: Re: [rt.cpan.org #44731] Unintended interpolation of variables in capturex()
Date: Thu, 9 Apr 2009 20:27:50 +0200
To: bug-IPC-System-Simple [...] rt.cpan.org
From: Ralph SOBEK <sobek [...] irit.fr>
Hi Paul, I _never_ noticed that there wer two different eval's in perl. That solves evrything! Thanks again, for all your help. --Ralph Show quoted text
>>>>> "PJF" == PJF via RT <bug-IPC-System-Simple@rt.cpan.org> writes:
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PJF> <URL: https://rt.cpan.org/Ticket/Display.html?id=44731 > PJF> G'day Ralph,
Show quoted text
PJF> On Mon Apr 06 14:08:25 2009, sobek@irit.fr wrote:
Show quoted text
>> You are absolutely right! But the code was suggested in the man >> page >> section in order to protect from exceptions within the code:
Show quoted text
PJF> Aha! You've discovered the difference between eval(), which does a PJF> "string eval", and eval {}, which does a "block eval".
Show quoted text
PJF> The first considers its argument to be a string of Perl code, and PJF> evaluates it. It's almost never something you want. The second acts PJF> just like a "try" block in other languages.
Show quoted text
PJF> So, for your example, you should be able to use:
Show quoted text
PJF> my @lines = eval { PJF> capturex(EXIT_ANY, $GREP, $mid, @FILES); PJF> };
Show quoted text
PJF> if ($@) { print "Oh noes! Something went wrong!\n"; }
Show quoted text
PJF> It's unfortunate that Perl has two different forms of 'eval'. If you PJF> use the Error module[1] from the CPAN, you can actually write 'try {}' PJF> instead of 'eval {}'. Likewise, if you're using Perl::Critic[2], it PJF> will complain loudly if it ever sees you using a string eval (since it's PJF> almost never needed).
Show quoted text
PJF> All the very best,
Show quoted text
PJF> Paul
Show quoted text
PJF> [1] http://search.cpan.org/search?query=Error PJF> [2] http://search.cpan.org/perldoc?perlcritic
  Thu Apr 09 14:28:47 2009 The RT System itself - Status changed from 'resolved' to 'open'
  Fri Apr 10 09:59:37 2009 PJF [...] cpan.org - Correspondence added
G'day Ralph, On Thu Apr 09 14:28:45 2009, sobek@irit.fr wrote: Show quoted text
> I _never_ noticed that there were two different evals in perl. > Thanks again, for all your help.
Excellent! I'm glad to have helped! All the best, Paul
  Fri Apr 10 09:59:39 2009 PJF [...] cpan.org - Status changed from 'open' to 'resolved'