Beefy Boxes and Bandwidth Generously Provided by pair Networks
Perl-Sensitive Sunglasses

The Monastery Gates

( #131=superdoc: print w/ replies, xml ) Need Help??

Donations gladly accepted

If you're new here please read PerlMonks FAQ
and Create a new user.

New Questions
How to capture compile errors from child program?
2 direct replies — Read more / Contribute
by bulrush
on Jul 31, 2015 at 06:03
    I have a parent program, that calls a child program,, like this:
    @z=`perl -option1 -option2`
    The whole command line for is in a scalar variable but that shouldn't matter. So I noticed that @z in would return completely blank after I made some changes to Lo and behold I had compile or syntax errors in, so none of my other error messages (written to STDOUT with "print") would be written from

    So when I'm running, how do I capture compile errors when calling Do I have to do something like

    @z=`perl -c`;
    before I do anything else? Will @z return STDERR messages or just STDOUT? If I did
    @z=`perl -option1 -option2` or die "Possible compile errors in";
    Would that do what I want?

    Thank you. Looking for some input so I can learn more about this.

Replacement for the "unsupported" Graph module?
1 direct reply — Read more / Contribute
by pokki
on Jul 31, 2015 at 05:54

    Hello Monks,

    I've used the Graph module for lots of graph-related tasks and I've always been happy with it. I don't need a superfast module, or one that consumes very little memory, since I don't have many graphs and they aren't very big. I don't need complex operations either; neighbor/descendant/ancestor list, maybe some shortest paths.

    Is there an heir to Graph, now that its author has stopped maintaining it? Or should I just keep using it and hope it doesn't break in the future? What do you guys use, or do you just write your own adjacency maps?

Email Module
3 direct replies — Read more / Contribute
by caseycole589
on Jul 31, 2015 at 03:16

    I'm trying to convince my work to use Perl for our email in a web app running on is this do able or does any one have advice/opinions. How hard is it to get something like this working on a windows server? Any input would be appreciated. I know I could do this easily in c# and probably should, but I'm looking for any excuse to get Perl running on our servers. That way I can have an excuse for using it on more projects moving forward.

Rolling variable
7 direct replies — Read more / Contribute
by artperl
on Jul 30, 2015 at 09:35
    Dear Perl monks, I would like to seek recommendation on what could be a good solution here... I would like to monitor file count in a specific directory & record the count every hour. I would need to keep that counts somewhere for another calculation but I would like to keep only the last 8 counts, meaning throw away the oldest data & just keep the last 8 records. How can I effectively do this in perl? Thanks much!...
INIT {$SIG{__DIE__} and Getopt::Long
5 direct replies — Read more / Contribute
by demichi
on Jul 29, 2015 at 13:16
    Hi all

    I am normally using the following line to capture the die output into a logfile.

     INIT {$SIG{__DIE__}=sub {LOG_MSG("normal",3,"GENERAL","Script died: $_[0]") and close LOG;}}

    Now I am using also Getopt::Long. I don't want to have a logfile generated if somebody is chosing the wrong parameter. Therefore I let the script die with an usage output.

    Unfortunately if somebody choses a wrong getopt parameter now - I get a log error message because of the INIT-"die" setting as the log file is not opened yet.

    G:\development\bin> -x > 4,GENERAL,Script warning: Unknown option: x print() on unopened filehandle LOG at G:\development\bin\ line 45. + ### Version:2.0.0 NAME xxx > 3,GENERAL,Script died: 1 at G:\development\bin\ line 14. ### > 4,GENERAL,Script warning: print() on unopened filehandle LOG at G:\d +evelopment\bin\ line 45. ### print() on unopened filehandle LOG at G:\development\bin\ line 45. + ### 1 at G:\development\bin\ line 14. ### G:\development\bin>

    Every line marked with "###" at the end I do not want to have as output to STDOUT.

    Do you have an ideas how can fix it? Thanks.

    kind regards de Michi

    use strict; use warnings; use Getopt::Long qw(:config no_ignore_case bundling); # Get options / my $VERSION = "2.0.0"; INIT {$SIG{__DIE__}=sub {LOG_MSG("normal",3,"GENERAL","Script died: $_ +[0]") and close LOG;}} INIT {$SIG{__WARN__}=sub {LOG_MSG("normal",4,"GENERAL","Script warning +: $_[0]")}} # Check Flags my $flag_help; my $flag_version; my $flag_config; GetOptions ( 'h|help' => \$flag_help, 'V|VER' => \$flag_version, 'c|config=s' => \$flag_config, ) or die USAGE(); # Check flags and print usage if ($flag_version) { print "Version: $VERSION\n"; exit; } if ($flag_help) { USAGE(); exit; } open(LOG,"> SCRIPTLOG_FILE") or die ("Can't open SCRIPTLOG_FILE: $!\n" +); close LOG; ### subs sub LOG_MSG { my $par_LEVEL = shift (@_); my $par_SEVERITY = shift (@_); my $par_FUNCTION = shift (@_); my @line = @_; print "> $par_SEVERITY,$par_FUNCTION,@line\n"; print LOG "$par_SEVERITY,$par_FUNCTION,@line\n"; } sub USAGE { my ($message)=<<'MESSAGE'; NAME xxx MESSAGE print "Version:${VERSION}\n$message"; }
Consistent xml formatting
1 direct reply — Read more / Contribute
by Haloric
on Jul 28, 2015 at 10:05

    Hi Monks,

    I have many xml files that I am attempting to compare with either XML::SemanticDiff or XML::SemanticCompare.

    Is there a way to get the XML ordered in a consistent way before I start this comparison, without calling out to a separate tool. They both get confused by slight ordering changes

    For example, I have elements that are

    <sequence name="b" .. <sequence name="a" .. <sequence name="c" ..

    I would like them ordered by the 'name' attribute before the comparison starts.

    I have looked at XML::LibXML::PrettyPrint but can't make it do what I want.

    I can see SemanticDiff copes with missing attributes, but not sure how it would cope with a missing '<sequence name="b" ' element all together without thinking it was a difference in attribute value, rather than entirely missing.


How to call a perl function without its context?
9 direct replies — Read more / Contribute
by kitomer
on Jul 28, 2015 at 05:34
    I want to call a Perl function and be sure it cannot access any variables declared in its context, just its local variables and passed arguments. Is this possible?
Performance of assambled regex
6 direct replies — Read more / Contribute
by Foodeywo
on Jul 26, 2015 at 08:04
    Dear Monks,

    today I re-stumbled upon an issue I quick-and-dirty solved a while ago but I want to solve it more elegantly while I am doing code polishing these days.

    I use Regexp::Assemble to assemble regex that are about 15kb to 87kb large. Now I very simply run through a large (~10GB) file and match the regex. I used to do this on the command line in the style

    perl -ne 'print if (/MYLARGEREGEX_HERE/../END_OF_BLOCK/)' inputfile > +outputfile

    this was fast as hell. However when my regex grew in size, I was not able to copy paste them into the bash so I started to read the regex from a file and did something like this

    #!perl use strict; use warnings; open my $fh_big_file, '<', $ARGV[0] || die; #first argument must be th +e input file open my $fh_regex, '<', $ARGV[1] || die; # second argument points to t +he file containing the regex my $regex = <$fh_regex>; while(<$fh_big_file>) { print if (/$regex/../^END_OF_BLOCK/); }

    The funny thing is, that this flavour of code costs me factor 20 in speed or even more. I can reclaim the speed by avoiding to store the regex in a variable, e.g.

    while(<$fh_big_file>) { print if (/MY_HUGE_REGEX_JUST_PLAIN/../^END_OF_BLOCK/); }

    so I assume this has something to do with fetching the content of the variable (from RAM to CPU?) over and over for each loop of while(<>), whereas inputing the regex directly doesnt need to re-read it every time.

    This approach however requires me to manually copy the regex to its place each time I run the whole procedure of "assembling, searching, processing, assembling, seachring, processing" and I would like to automize it without loss of performance. Any ideas?

    thanks and cheers!


    The suggestion to use the o operator works. However it needs to be behind /$regex/ not behind /END_OF_BLOCK/. i.e. like shmem suggested:

    while(<$fh_big_file>) { print if (/$regex/o .. /^END_OF_BLOCK/); }


Pack + Fat32 timestamp
2 direct replies — Read more / Contribute
by tbr123psu
on Jul 25, 2015 at 18:06

    esteemed monks:

    greetings all! i've been struggling with this for days now, and figured it was finally time to ask for some help.

    I've been following the instructions found at to set up a wifi SD card for use in a photoframe. I wanted to use Perl rather than the python referenced on the page because I generally prefer perl and because i kinda wanted to do it myself.

    it's been smooth sailing, right up to the point of having to submit a FAT32 timestamp to set the creation date of the uploaded file. This part has me completely stumped.

    i've been all over google, and the best reference I can find about the required formats is from this thread on stackoverflow: There's no search results here for fat32.

    interestingly enough, I was able to figure out how interpret the dates coming off the card (for the purposes of knowing which photos were the last ones added, so I can only upload new ones), but trying to apply the same logic in reverse did not work so well. I'm also not entirely clear on why it worked the way it did, such that they come out split up but when going in, the card wants just one string, but I suppose that's just quirkiness in the API i've got to live with.

    anyhow, i suspect the answer has something to do with pack, but i won't lie, i'm just flinging stuff at the wall in the hopes that it sticks. I thought i was making progress, in that I have some idea what the actual value for a current timestamp is that would be submitted to the api call (through trial and error/guesswork -- manually trying to make things up, based on the example given in the API documentation

    so i've got some idea what the value needs to look like, but for the life of me i can't get that output to generate programatically. it seems that it's inclusive of 0-9 and a-f, so it seems like a hexadecimal number (as per, but being honest, this gets a little deeper than i usually go. thinking about it sometimes makes my head hurt.

    has anyone ever bumped into anything like this before or can offer any insight? code snippets below that do the relevant stuff with dates/times.

    here's the code that pulls the time and date from the card and interprets it.

    #Each row of the list is returned in the following format. #<directory>, <filename>, <size>, <attribute>, <date>, <time> # date 16 bit int -- bit 15-9 value based on 0 as 1980, bit 8-5 month +value from 1 to 12, bit 4-0 day, value from 1 to 31 # time 16 bit int -- bit 15-11 hour, 10-5, minute, 4-0 second / 2 # size my $fileList = getHttp($cardip, "command.cgi?op=100&DIR=/"); #print ($fileList . "\n"); my @fileArray = split("\n", $fileList); my @fileTimesArray; my $lastTime = 0; print (ref(@fileArray) . "\n"); foreach my $file (@fileArray) { if (index($file, ",") != -1) { print "working with file $file\n"; my ($directory, $name, $size, $att, $date, $time) = split(",", + $file); # example date, time = 18151,39092 my $day = ($date >> 0) & (2**5-1); my $month = ($date >> 5) & (2**4-1); my $year = ($date >> 9) & (2**7-1); $year = 1980 + $year; my $second = ($time >> 0) & (2**5-1); my $minute = ($time >> 5) & (2**6-1); my $hour = ($time >> 11) & (2**5-1); $second = $second * 2; print ("file: $name | $month - $day - $year | $hour : $minute +: $second | $epochTime\n"); #print ("file: $name | $date | $time\n"); #print ("day: $day\n"); #print ("month: $month\n"); #print ("year: $year\n"); #print ("second: $second\n"); #print ("minute: $minute\n"); #print ("hour: $hour\n"); my $perlMonth = $month - 1; my $epochTime = timelocal($second,$minute,$hour,$day,$perlMont +h,$year); if ($epochTime > $lastTime) { $lastTime = $epochTime; } push @fileTimesArray, { file => $name, epoch => $epochTime, si +ze => $size }; } }

    and here's the code for trying to generate a timestamp based on the timestamp returned from the file on disk.

    @info = stat($path->{file}); my $createdtime = $info[10]; print "regular created time is: $createdtime\n"; my ($sec, $min, $hour, $day,$month,$year) = (localtime($createdtim +e))[0,1,2,3,4,5]; # You can use 'gmtime' for GMT/UTC dates instead of 'localtime' $month++; my $displayYear = $year; my $realYear = $year; $year = $year - 80; $second = ceil($sec / 2); # example date, time = 18151,39092 --> not same format!?! # time 16 bit int -- bit 15-11 hour, 10-5, minute, 4-0 second / 2 #my $encSecond = $second & (2**5-1); #my $encMinute = $minute & (2**6-1); #my $encHour = $hour & (2**5-1); # date 16 bit int -- bit 15-9 value based on 0 as 1980, bit 8-5 mo +nth value from 1 to 12, bit 4-0 day, value from 1 to 31 #my $encDay = $day & (2**5-1); #my $encMonth = $month & (2**4-1); #my $encYear = $month & (2**7-1); #use integer; my $data = $year . $month . $day . $hour . $min . $second; print "using $data as input for pack\n"; #my $data = $second . " " . $minute . " " . $hour . " " . $day . " + " . $month . " " . $year; #my $createdtimeFat = pack "N8", $data; my $createdtimeFat = pack "N8", $year,$month,$day,$hour,$min,$sec +ond; #my $createdtimeFat = ($year << 25) | ($month << 21) | ($day << 1 +6) | ($hour << 11) | ($min << 5) | ($second << 0); #my $createdtimeFat = (($year & (2**7-1)) << 25) | (($month & (2* +*4-1)) << 21) | (($day & (2**5-1)) << 16) | (($hour & (2**5-1)) << 11 +) | (($min & (2**6-1)) << 5) | (($second & (2**5-1)) << 0); # 8 digits # 8 = year # 7 = year + month # 6 = month + day # 5 = day #### # 4 = hour # 3 = hour + month # 2 = minute + second # 4 = second #my $createdtimeFat = '469f9f01'; #my $hex = sprintf("0x%x", $createdtimeFat); #my $hex = printf("%x",$createdtimeFat); print "Unix time ".$createdtime." converts to ".$month." ".$day.", + ".($displayYear+1900)." ".$hour.":".$min.":".$sec." year (in offset +from 1980) is $year [real year is $realYear]\n"; #print $encSecond ." ". $encMinute ." ". $encHour ." ". $encDay ." + ". $encMonth ." ". $encYear . "\n"; print "createdtimeFat should look something like 46ef99c6\n"; print "createdtimeFat is $createdtimeFat\n"; my @unpacked = unpack("N8",$createdtimeFat); print "and unpacked: " . @unpacked . "\n"; my $setdate = getHttp($cardip, "upload.cgi?FTIME=0x" . $createdtim +eFat); print "result of setdate operation: $setdate\n";

    and this is the getHttp function/sub

    sub getHttp() { my $ip = shift; my $args = shift; my $status; my $url = "http://" . $ip . "/" . $args; #print ("accessing " . $url . "\n"); # set custom HTTP request header fields my $req = HTTP::Request->new(GET => $url); my $resp = $ua->request($req); if ($resp->is_success) { my $message = $resp->decoded_content; #print "Received reply: $message\n"; $status = $resp->decoded_content; } else { print "HTTP GET error code: ", $resp->code, "\n"; print "HTTP GET error message: ", $resp->message, "\n"; $status = $resp->message; } return $status }

    many thanks in advance for any help or guidance anyone can offer - i'm at wit's end, and i feel like i've got to be missing something!

ssl details cgi script
3 direct replies — Read more / Contribute
by alokranjan
on Jul 25, 2015 at 15:04
    Hi All, Can anyone please have a look at my cgi script to print the ssl certificate expirt date. I am picking the sitename from a html page and passing to the below cgi:
    use CGI qw(:standard); use CGI::Carp qw(warningsToBrowser fatalsToBrowser); use Net::SSL::ExpireDate; use strict; my $sitename; my $ed; my $expire_date; print header; print start_html("Thank You"); print h2("Thank You"); my %form; foreach my $p (param()) { $form{$p} = param($p); print "$p = $form{$p}<br>\n"; $sitename = $form{$p}; } #$sitename = ""; chomp($sitename); $sitename =~ s/^\s+|\s+$//g; print "\nWebsite name is: $sitename.\n"; $ed = Net::SSL::ExpireDate->new( https => $sitename ); if (defined $ed->expire_date) { $expire_date = $ed->expire_date; print "$expire_date\n"; } print end_html;
    I am wondering why its not working, though a separate Perl script is working fine to get the expiry date. Any help/assistance would be highly appreciated.

    Thanks, Alok

Getting constructor caller in Mo/Moo/Moose BUILD/BUILDARGS
2 direct replies — Read more / Contribute
by perlancar
on Jul 25, 2015 at 07:58

    What is the proper way to get the caller to our object creation (the object's client code) inside Mo/Moo/Moose's BUILD or BUILDARGS? I'm okay with getting a subclass.

    From a quick glance of the Moo and Moose codebase, it doesn't seem like Moo/Moose provides a utility routine for this. A quick search on CPAN also doesn't yield anything yet.


    package Class1; use Moo; has attr1 => (is => 'rw'); sub BUILD { no strict 'refs'; my $self = shift; # XXX set default for attr1 depending on the caller unless (defined $self->attr1) { $self->attr1(${"$object_caller_package\::FOO"}); } } package C2; use Moo; extends 'C1'; package main; our $FOO = 42; say C2->new->attr1; # prints 42

    In principle it should be easy enough to loop over the caller stack and use the first non-Moo* stuff.

RFC: Name and/or API for module ("HTML::RewriteURLs")
5 direct replies — Read more / Contribute
by Corion
on Jul 25, 2015 at 05:45

    Once again, I have a module but no name. I come here in the hope of finding a good name that helps others find this module and put it to good use.

    Let me first describe what the module does:

    The module exports two functions, rewrite_html and rewrite_css. These functions rewrite all things that look like URLs to be relative to a given base URL. This is of interest when you're converting scraped HTML to self-contained static files. The usage is:

    use HTML::RewriteURLs; my $html = <<HTML; <html> <head> <link rel="stylesheet" src="http://localhost:5000/css/site.css" /> </head> <body> <a href="">Go to</a> <a href="http://localhost:5000">Go to home page/a> </body> </html> HTML my $local_html = rewrite_html( "http://localhost:5000/about", $html ); print $local_html; __END__ <html> <head> <link rel="stylesheet" src="../css/site.css" /> </head> <body> <a href="">Go to</a> <a href="..">Go to home page/a> </body> </html>

    The current name for the module is HTML::RewriteURLs, and this name is bad because the module does not allow or support arbitrary URL rewriting but only rewrites URLs relative to a given URL. The functions are also badly named, because rewrite_html doesn't rewrite the HTML but it makes URLs relative to a given base. And the HTML::RewriteURLs name is also bad/not comprehensive because the module also supports rewriting CSS.

    I'm willing to stay with the HTML:: namespace because nobody really cares about CSS before caring about HTML.

    I think a better name could be HTML::RelativeURLs, but I'm not sure if other people have the same association. The functions could be renamed to relative_urls_html() and relative_urls_css().

    Another name could be URL::Relative or something like that, but that shifts the focus away from the documents I'm mistreating to the URLs. I'm not sure what people look for first.

    Below is the ugly, ugly regular expression I use for munging the HTML. I know and accept that this regex won't handle all edge cases, but seeing that there is no HTML rewriting module on CPAN at all, I think I'll first release a simpleminded version of what I need before I cater to the edge cases. I'm not fond of using HTML::TreeParser because it will rewrite the document structure of the scraped pages and the only change I want is the change in the URL attributes.

    =head2 C<< rewrite_html >> Rewrites all HTML links to be relative to the given URL. This only rewrites things that look like C<< src= >> and C<< href= >> attri +butes. Unquoted attributes will not be rewritten. This should be fixed. =cut sub rewrite_html { my($url, $html)= @_; $url = URI::URL->new( $url ); #croak "Can only rewrite relative to an absolute URL!" # unless $url->is_absolute; # Rewrite relative to absolute rewrite_html_inplace( $url, $html ); $html } sub rewrite_html_inplace { my $url = shift; $url = URI::URL->new( $url ); #croak "Can only rewrite relative to an absolute URL!" # unless $url->is_absolute; # Rewrite relative to absolute $_[0] =~ s!((?:src|href)\s*=\s*(["']))(.+?)\2!$1 . relative_url(UR +I::URL->new( $url ),"$3") . $2!ge; }

    Update: Now released as HTML::Rebase, thanks for the discussion and improvements!

New Meditations
Time for an application portfolio
7 direct replies — Read more / Contribute
by talexb
on Jul 27, 2015 at 12:04

    I have been tinkering with a few tools lately, and now want to put up a portfolio of some web applications that I am working on. I have an account on pair Networks (they also host this site), so I set up local::lib and went ahead and tried to install Mojolicious::Lite, since that's the platform I'm working on these days.

    No dice -- Mojo::Lite requires 5.10, and pair only has 5.8.9. I checked with the other provider I use, and they have 5.8.8.

    So the two options I can see are a) install an up-to-date Perl on one of those accounts, or b) have these web applications run on my home machine (perhaps using to provide consistent name resolution -- not sure is this is still available).

    I could go find another web provider, but that's additional expense, and not really my best option right now. Feedback welcome!

    Alex / talexb / Toronto

    Thanks PJ. We owe you so much. Groklaw -- RIP -- 2003 to 2013.

Log In?

What's my password?
Create A New User
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others browsing the Monastery: (17)
As of 2015-07-31 14:20 GMT
Find Nodes?
    Voting Booth?

    The top three priorities of my open tasks are (in descending order of likelihood to be worked on) ...

    Results (278 votes), past polls