Beefy Boxes and Bandwidth Generously Provided by pair Networks
"be consistent"

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
using perl to get sms messages
3 direct replies — Read more / Contribute
by Datz_cozee75
on Oct 26, 2016 at 17:54

    Hello Monks,

    Is there a perl way to get the sms messages off my phone? If it matters, I have a $69 Blu android that I regret buying as the internal storage was quite simply fraudulently-advertised at 4 gigs. It is 2 gigs, and with OS loaded, 1. (What did I expect for seventy bucks?)

    Anyways, I've got someone who's trying to put the squeeze on me and appears not to know why that isn't a good idea. Are there other software tools for this purpose? Thank you for your comment.

fork(): terminating the child without killing the parent
3 direct replies — Read more / Contribute
by Bloehdian
on Oct 25, 2016 at 20:25

    Hello Monks,

    I wrote a test application in which the process is forked. The resulting parent process sends a message continuously via pipe using syswrite to the child.

    I installed a signal handler in the parent for signal SIGHUP, so that I can "advice" the parent from the command line to terminate the child (on sending SIGHUP to the parent process). At least I try to do this.

    Here is the code:

    use strict; use warnings; use Errno qw( EWOULDBLOCK ) ; my $from_parent; my $to_child; my $pid; my $mesg_parent = "Hello Child!"; my $mesg_child; my $test; pipe( $from_parent, $to_child ); if ( $pid = fork() ) { # Parent $SIG{ HUP } = sub{ kill( 15 , $pid ); print( "KILLED CHILD!!!\n" ) +}; close( $from_parent ); while ( 1 ) { eval{ $test = syswrite( $to_child, $mesg_parent, length( $mesg_p +arent ) ); }; select( undef, undef, undef, .5); if ( $@ ) { print( "trapped error when writing to pipe \$to_child_ssl\n" +); next; } if ( defined $test ) { print( "Sent message \"$mesg_parent\" to child\n" ); } } } else { # Child close( $to_child ); while ( 1 ) { $test = sysread( $from_parent, $mesg_child, 13 ); select( undef, undef, undef, .5 ); if ( ! defined $test ) { if ( $! == EWOULDBLOCK ) { print( "sysread would be blocked by \$from_parent: $!\n" ) +; next; } else { die ( "Error when trying to read from \$from_parent: $!\n" + ); } } print( "In child\n" ); print( $mesg_child . "\n" ); $mesg_child =~ s/Child/Parent/; print $mesg_child . "\n"; } }

    When I run the script and execute

    kill -1 <pid>

    in a different terminal window with <pid> being the parent process's PID than the final output is as follows:

    Sent message "Hello Child!" to child In child Hello Child! Hello Parent! Sent message "Hello Child!" to child In child Hello Child! Hello Parent! KILLED CHILD!!! Sent message "Hello Child!" to child Sent message "Hello Child!" to child xyz@v32470:~/projekte/$

    i.e., not only the child┤, but the parent as well is terminated.

    If I use

    kill 1 <pid>

    then obviously only the parent process is killed, the child continues to run:

    In child Hello Child! Hello Parent! Terminated xyz@v32470:~/projekte$ In child Hello Child! Hello Parent! In child In child In child In child

    The kill command comes back with an error message btw:

    xyz@v32470:~$ kill 1 31055 -bash: kill: (1) - Operation not permitted

    How can this behaviour explained and how could I reach that only the child is killed by the parent and the parent continues to work?

    The backgroud: I want to use this code as the basis for a script in which the parent checks whether the child is still running by sending messages via pipe to the child and checks the response (i.e., in the final version the communication would be bidirectional).

    Is this feasible using this approach at all?

    From my ┤point of view it boils down to the qestion whether I could trap an error as indicated in the script when trying to syswrite() to the Řipe after the child passed away. Is this possible?

    Cheers Bloehdian
Syntax Question Related to "join" on a Complex Data Structure
2 direct replies — Read more / Contribute
by perldigious
on Oct 25, 2016 at 17:12

    Due to my own programming vocabulary deficiencies, poor Google foo, or both I'm unable to search effectively for an answer to this syntax question. Sparing what I hope is unnecessary detail, I have in the past done the following and was amazed (not for the first time) that Perl let me do this and furthermore did exactly what I wanted.

    my $sales_line = join "\t", @data[@sales_indexes{@sales_columns}];

    Where I use the @sales_columns array to give me a hash slice of %sales_indexes (using @ instead of % for a list) which I use to take an array slice of @data, join it with tabs, and then store the result as the $sales_line string. Yeah... I think I said that all correctly. When this worked it was one of those, "damn I love Perl" moments for me. I often physically walk over to the only other Perl user I know and say exactly that whenever they happen.

    Which brings me to my question, because it's somewhat similar, and it's a rare case of Perl not understanding what I meant and/or doing what I wanted, and I'm hoping the error is mine and I just have the exact syntax wrong. I tried the following which gives a syntax error.

    my $transcripts_line = join "\t", @transcripts{$transcript_ip}{$transcript_id}{@transcripts_columns};

    Where %transcripts is a 3D hash that I'm trying to use the same up front @ instead of % trick to get the value list I want from the hash slice that I was hoping would be provided by the @transcripts_columns array ($transcript_ip and $transcript_id are simple scalars). I attempted the below as well, which doesn't give a syntax error, but doesn't work as expected either.

    my $transcripts_line = join "\t", ($transcripts{$transcript_ip}{$transcript_id}{@transcripts_columns});

    The way I did solve my problem was as follows.

    my $transcripts_line = join "\t", map {$transcripts{$transcript_ip}{$transcript_id}{$_}} @transcripts_columns;

    Which is fine, but... the first line of code I gave that worked was just so, well... succinct and pretty. :-)

    As I said, I'm hoping I've just messed up the syntax with what I originally tried and I don't actually have to resort to the map inside of a join to make this work.

    Any thoughts from the monastery?

    I love it when things get difficult; after all, difficult pays the mortgage. - Dr. Keith Whites
    I hate it when things get difficult, so I'll just sell my house and rent cheap instead. - perldigious
Devel::Size reports different size after hash access
4 direct replies — Read more / Contribute
by Cristoforo
on Oct 25, 2016 at 15:40
    While working on a problem, I came across something I couldn't explain.

    When asking for the size of a newly created hash, it gave me one size. But after accessing the hash, it gave a size almost 50% larger.

    #!/usr/bin/perl use strict; use warnings; use Devel::Size 'total_size'; my $s = 'AAAAAAAAAAAAAAA'; my %hash = map {$s++ => 1} 1 .. 1000; print total_size(\%hash). ' ' . keys(%hash) . "\n"; open my $fh, '>', 'j1.txt' or die $!; for my $key (keys %hash) { print $fh "$key $hash{$key}\n"; } print total_size(\%hash). ' ' . keys(%hash) . "\n";
    The results of running this code was:
    105248 1000 145288 1000

    I'm using perl version 5.014 and the version of Devel::Size is .08.

If line matches, print column, else print file name
2 direct replies — Read more / Contribute
by Yakup
on Oct 25, 2016 at 14:05

    Hello everyone. I had used Perl a little bit long time ago and now I'm trying to write a little program, but I have got stuck. I would like to check bunch of kickstart files for a '--hostname=' pattern. If it matches I want to get the collumn right after it (actual hostname). Else it should take the name of the file (stripped of '.ks' suffix) and save all of them to the array. Commented lines should not be taken. This is how I have done it in bash + awk

    #!/bin/env bash declare -a hostlist=$(grep -P '(?<!#)--hostname' *.ks | awk -F'=' '{pr +int $2}') declare -a not_predefined_hosts=$(grep -L "\-\-hostname" *.ks | cut -d +\. -f1 ) declare -a commented=$(grep -l ".*#.*\-\-hostname" *.ks | cut -d\. -f1 + ) for host in "${not_predefined_hosts[@]}" do hostlist+="$host" done for host in "${commented[@]}" do hostlist+="$host" done

    This works, but when I want to do it with perl, I get multiple issues.

    #!/usr/bin/env perl use strict; use warnings; use File::Basename; my $lab_root = dirname $0; opendir( DH, $lab_root) or die "Cannot open $lab_root: $!\n"; my @kickstarts = grep ( /\.ks$/, readdir(DH)); my @bsname ; my $hostname; for my $kickstart (@kickstarts) { my $name = (split /\./)[0], $kickstart; open my $fh, $kickstart or die "Cannot open $kickstart: $!"; while (<$fh>) { chomp; my @fields = split /=/; if ( $fields[0] eq '--hostname') { $hostname = $fields[1]; print "$hostname\n"; push @bsname , $hostname; }else { $hostname = $name; print "$hostname\n"; push @bsname , $hostname; } close $fh; } }

    First, I get the warnings

    Provisioner]$ ./ Useless use of private variable in void context at ./ line + 13. Use of uninitialized value $_ in split at ./ line 13. Use of uninitialized value $hostname in concatenation (.) or string at + ./ line 24, <$fh> line 1. readline() on closed filehandle $fh at ./ line 27. Use of uninitialized value $_ in split at ./ line 13. readline() on closed filehandle $fh at ./ line 27. Use of uninitialized value $_ in split at ./ line 13. Use of uninitialized value $hostname in concatenation (.) or string at + ./ line 24, <$fh> line 1. readline() on closed filehandle $fh at ./ line 27. Use of uninitialized value $_ in split at ./ line 13. Use of uninitialized value $fields[0] in string eq at ./ l +ine 18, <$fh> line 1. Use of uninitialized value $hostname in concatenation (.) or string at + ./ line 24, <$fh> line 1. readline() on closed filehandle $fh at ./ line 27.

    I don't understand why I'm getting "Use of uninitialized value" warnings, when I initialize all variables with "my" beforehand. Also, why does the filehandle "$fh" close before the close statement? And what the "Useless use of private variable in void context" mean? All examples I was able to google on it were very different from my code and didn't help me to understand that.

    Second, when the code runs,( with added 'print @bsname;' ) it matches only once (but strangely prints twice). There are multiple kickstart files with "--hostname" directive in it, but it ignores the rest. Also the "else" part doesn't work (none of the file names are matched).

    [################### Provisioner]$ ./[################### Provisioner]$

    Can somebody please point out mistake in my code? I'm sure it will be something trivial, but I can't wrap my head around it. Thanks!

IPC::Run command is correctly constructed but does not have effect
1 direct reply — Read more / Contribute
by byrnejb
on Oct 25, 2016 at 12:55

    I am hacking at an old perl scrip that is used to generate and maintain a private CA. The script contains this code:

    . . . use IPC::Run qw( start pump finish timeout new_appender new_chunker); . . . sub cmd { my $self = shift; my $cmd = shift; my $cmdline = shift; my $args = shift; my $conf; my $cfgcmd; if ( (grep $_ eq $cmd,qw(req ca)) && !$args->{noconfig}) { $conf = $self->{csp}->writeConfig($cmd,$args); $self->{csp}->die("Unable to write configuration file") unless -f $c +onf; $cfgcmd = " -config $conf "; } elsif ($cmd eq 'x509' && !$args->{noconfig}) { $conf = $self->{csp}->writeConfig($cmd,$args); $self->{csp}->die("Unable to write configuration file") unless -f $c +onf; $cfgcmd = " -extfile $conf -extensions extensions "; } $cmd = '' if $cmd eq 'dummy'; ${$self->{_in}} = "$cmd $cfgcmd $cmdline"; if ($ENV{CSPDEBUG}) { $self->warn("Here I am"); $self->warn("# openssl $cmd $cfgcmd $cmdline\n"); } $self->{_handle}->pump while length ${$self->{_in}}; $self->{_handle}->finish; . . .
    When I run this command
    csp CA_HLL_ROOT_2016 init --verbose --type=root --keysize=4096 --days= +7317 --dige +st=sha512 "CN=CA_HLL_ROOT_2016,OU=Networked Data Services,O=Harte & L +yne Limited,L=Hamilton,ST=Ontario,C=CA,DC=harte-lyne,DC=ca"
    then I get this result:
    [CSP][ ] Here I am [CSP][ ] # openssl genrsa -des3 -passout pass:'test me' -out / +home/byrnejb/Projects/Software/rcsp/ca_test_a/csp/CA_HLL_ROOT_2016/pr +ivate/ca.key 4096 [CSP][ ] Here I am [CSP][ ] # openssl req -config /home/byrnejb/Projects/Software +/rcsp/ca_test_a/csp/CA_HLL_ROOT_2016/tmp/csp-32489.conf -x509 -sha51 +2 -days 7317 -key /home/byrnejb/Projects/Software/rcsp/ca_test_a/csp +/CA_HLL_ROOT_2016/private/ca.key -passin pass:'test me' -new -out /ho +me/byrnejb/Projects/Software/rcsp/ca_test_a/csp/CA_HLL_ROOT_2016/ca.c +rt

    There are no errors but the files specified in the command lines are not created. If I copy and paste the command lines that are output from the warn statements then the files are created without problem.

    I have zero experience with Perl. Well, not quite zero any more but not much. Is there something obvious that I am missing here? The entire project is available on github at if more context is desired.

Packaging Libraries before deploying my Scripts.
2 direct replies — Read more / Contribute
by ArunMKumar
on Oct 25, 2016 at 07:02
    Namaste Monks.. I have written a set of scripts, on a local system (my laptop) The work fine here.
    Now My scripts are required to be deployed in remote system(s) and the thing I am worried about is the availability and the installation of the Libraries that I have used.
    The 2 Libraries that are currently in use are "XML::LibXML" and "Spreadsheet::ParseExcel".
    I have this idea where I will put them in a "lib" directory in the same project Directory, and the scripts will refer from them. My questions are as follows.
    I have installed them in a directory, using the commands as follows from the extracted tar files.

    perl Makefile.Pl
    make test
    make install PREFIX=<path_to_lib> LIB=<path_to_lib>

    I also see the .pm files being populated in various tree structures in that lib directory.
    My question now is , How do i force my scripts to reference this lib directory when It wants to look for the modules?
    I am new to perl, from what I searched online I think it has to do with modifying @INC variable, while some solutions say about explicitly including these versions of the library (which I have no clue, as those post included their own perl modules).
    so.. How do i force my scripts to use these libraries exclusively, and not throw an error when i deploy them to different systems (all Linux systems with perl 5 or above for sure).
heredoc and Carriage return
4 direct replies — Read more / Contribute
by gabrielsousa
on Oct 25, 2016 at 05:18

    heredoc read the LF ( \n ) , but dont parse / stores the Carriage return ( \r )

    how can i force heredoc to read and store carriers return ( \r ) ?

    =====================added before======================

    i have a pdf file / binary inside my perl script using heredoc
    has 40 Carriage returns, i can search on VI, i see the ^M
    but when i print to a file i lose all Carriage returns..
    i'm assuming is a problem of heredoc
Detecting stale pid file under *nix
4 direct replies — Read more / Contribute
by Dallaylaen
on Oct 24, 2016 at 17:36

    This is more of a Unix question rather than a Perl one, but still...

    I'm looking for a way to stop my daemon, but I don't want to terminate an innocent bystander process. I came up with idea that PID file is created after the process has been spawned. Therefore, it's not older then the process, so the following code was written which seems to work correctly on my Ubuntu:

    open (my $fd, "<", $conf->{pidfile}) or die "Failed to read pidfile $conf->{pidfile}: $!"; my $pid = <$fd>; chomp $pid; die "Broken pid file $conf->{pidfile}" unless $pid =~ /^\d+$/; # detect stale pid if ([stat $fd]->[9] >= ([stat "/proc/$pid"]->[9] || 9**9**9)) { print "Killing pid $pid...\n"; kill INT => $pid; };

    Of course, it can still be tricked by touching the pid file, but then it's also possible to write rubbish into the pid file anyway.

    Now I would like to ask what is the proper way of avoiding sending signal to a wrong process? CPAN has a multitude of modules for PID file handling, I was unable to choose one.

    Thank you!

Default import function
4 direct replies — Read more / Contribute
by Athanasius
on Oct 24, 2016 at 02:17

    According to the documentation for import:

    There is no builtin import function. It is just an ordinary method (subroutine) defined (or inherited) by modules that wish to export names to another module. The use function calls the import method for the package used.

    However, when I create an empty module (file “”):

    package MyMod; 1;

    and print out its symbol table (file “”):

    use strict; use warnings; use Data::Dump; use MyMod; dd \%MyMod::;

    the output shows that an import function is already present:

    16:10 >perl { import => *MyMod::import } 16:10 >

    Where does it come from? Is the documentation incorrect, or am I simply misreading it?


    Athanasius <°(((><contra mundum Iustus alius egestas vitae, eros Piratica,

XML::LibXML drives me to drinking
4 direct replies — Read more / Contribute
by tunafish
on Oct 22, 2016 at 19:37

    I'm trying to figure out XML::LibXML. It's rough going. I need to be able to access the text content of a node by name. Here is my code:

    #!/usr/bin/perl use strict; use XML::LibXML; my $string = qq~<?xml version="1.0"?> <ItemLookupResponse xmlns=" +ervice/2013-08-01"> <Items> <Item> <ASIN>B01KI4JSQY</ASIN> </Item> </Items> </ItemLookupResponse> ~; my $parser = XML::LibXML->new->load_xml(string => $string, {no_blanks +=> 1}); my $xml = XML::LibXML::XPathContext->new($parser); $xml->registerNs('x', ' +ce/2013-08-01'); # Parse items foreach my $item ($xml->findnodes('/x:ItemLookupResponse/x:Items/x:Ite +m', $parser)){ print $item->firstChild->nodeName, "\n"; print $item->firstChild->toString, "\n"; print $item->findvalue('ASIN'), "\n"; print $item->findvalue('./ASIN'), "\n"; print $item->findvalue('./ASIN', $item), "\n"; }

    Expected result:


    Actual result:


    Probably I'm just misunderstanding something in the docs. But I don't know what it is. I tried $item->findvalue('x:ASIN'), but that threw an error. Please help. I have a family. If I become an alcoholic, they will suffer.

Shortening paths for display
1 direct reply — Read more / Contribute
by morelenmir
on Oct 22, 2016 at 17:08

    There used to be an undocumented win32 function called 'PathSetDlgItemPath'. This allowed you to set the text of a windows control to a file or folder path, automatically editing what was displayed to fit inside the available client area. It did this where necessary by shortening the path using '...' ellipsis characters.

    I wondered if there was anything similar for perl? I guess, rather than the size of a windows control it would need to be told the maximum number of characters you wanted to display.

    "Aure Entuluva!" - Hurin Thalion at the Nirnaeth Arnoediad.
New Meditations
Testing Dancer applications with a custom database
No replies — Read more | Post response
by Corion
on Oct 24, 2016 at 13:10

    While developing a plugin for Dancer as a wrapper around one of my modules, I wanted to unit test my code using a mock database instead of the database I do interactive tests with. Surprisingly, I didn't find documentation on how to supply Dancer::Plugin::Database with your own test database.

    After some reading through the test suite of Dancer::Plugin::Database, it seems that the magic is in overwriting the configuration at the right time. To give this approach a broader exposure and to maybe invite some comments or better suggestions, let's look through the code:

    In the prelude, we load Dancer, Dancer::Test and the application I'm writing, tentatively named mychat. We plan for three tests:

    #!perl -w use strict; use warnings; use Test::More import => ['!pass']; use Data::Dumper; use Dancer ':syntax'; use DBIx::RunSQL; use Dancer::Plugin::Database; # the order is important use mychat; use Dancer::Test; plan tests => 3;

    Then, we set up our own in-memory database and create all tables and triggers from the SQL file stored in sql/create.sql. This gives us a pristine database that contains only initial data.

    # set up our own database instead of whatever is in the config my $conf = { Database => { dsn => 'dbi:SQLite:dbname=:memory:', connection_check_threshold => 0.1, sqlite_unicode => 1, dbi_params => { RaiseError => 0, PrintError => 0, PrintWarn => 0, }, }, }; set plugins => $conf; # Set up a fresh instance my $dbh = database; $dbh = DBIx::RunSQL->create( dbh => $dbh, sql => 'sql/create.sql', );

    Since what I really want to test is whether image upload and retrieval works, let's fake a PNG image and "upload" it into the application:

    my $payload = join '', "\x89", 'PNG', "\x0d\x0a", "\x1a", "\x0a", (map { chr($_) x (1024 * 256) } 1..3) ; # Insert image into database my $upload = Dancer::Request::Upload->new( filename => 'test.png', tempname => 'test2.png', size => length($payload), headers => { 'Content-Type' => 'image/png', }, ); # Insert into DB my $content = mychat::UserContent->store( config->{image_store}, $dbh, $upload, { extension => 'png', content_type => 'image/png', }, $payload );

    After all this setup, we can now run three tests as if we had a standard Dancer application and can check that URLs exist where we expect them and that we get the appropriate content from each URL:

    ok $content, "We successfully saved the user content"; route_exists(['GET', '/image_store/'], "We find /image_store/fo"); # Check that we can access it through /image_store/sha1.jpg my $name = $content->{digest} . ".png"; response_status_is ['GET',"/image_store/$name"], 200, "GET '/image_sto +re/$name' succeeds" or diag Dumper read_logs();
New Cool Uses for Perl
extracting strings from non-text files
1 direct reply — Read more / Contribute
by RonW
on Oct 20, 2016 at 21:09

    A coworker (on MS Windows) was cursing he couldn't see what symbol names might be hidden in a non-text configuration file for a proprietary, 3rd party tool he has to use. Since I didn't want to risk being constantly asked to "dump symbols" using my Lunix system, I took a few minutes to write the following program in Perl. Made him happy (for now, at least).

    Note: The tool being used only supports ASCII characters, so I didn't bother with encodings. Probably didn't need to specify ":bytes" in the open statement, but no harm in doing so.

    Maybe others will find this useful.

    #!perl use 5.010_000; use warnings; use strict; if ((@ARGV < 1)) { $0 =~ m#([^\\/]+$)#; my $name = $1 // $0; print STDERR "$name file ...\n" . <<'_DESCRIPTION_'; Extract ASCII strings from files listed. Multiple files allowed. _DESCRIPTION_ exit 1; } for my $file (@ARGV) { open my $fh, '<:bytes', $file or die "Error: Can't open '$file': $ +!\n"; my $buf; while (read $fh, $buf, 1024) { my @strings = split /\P{PosixGraph}/, $buf; for (@strings) { next if /^\s*$/; print "$_\n"; } } }
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 perusing the Monastery: (9)
As of 2016-10-27 17:17 GMT
Find Nodes?
    Voting Booth?
    How many different varieties (color, size, etc) of socks do you have in your sock drawer?

    Results (366 votes). Check out past polls.