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Perl program - Dynamic Bootstrapping code

- by mgj

Hi.. I need to understand the working of this particular program, It seems to be quite complicated, could you please see if you could help me understanding what this program in Perl does, I am a beginner so I hardly can understand whats happening in the code given on the following link below, Any kind of guidance or insights wrt this program is highly appreciated. Thank you...:) This program is called premove.pl.c Its associated with one more program premove.pl, Its code looks like this: #!perl open (newdata,">newdata.txt") || die("cant create new file\n");#create passwd file $linedata = ""; while($line=<>){ chomp($line); #chop($line); print newdata $line."\n"; } close(newdata); close(olddata); __END__ I am even not sure how to run the two programs mentioned here. I wonder also what does the extension of the first program signify as it has "pl.c" extension, please let me know if you know what it could mean. I need to understand it asap thats why I am posting this question, I am kind of short of time else I would try to figure it out myself, This seems to be a complex program for a beginner like me, hope you understand. Thank you again for your time.

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How to print a Perl 2-dimensional array?

- by Matt Pascoe

I am trying to write a simple Perl script that reads a *.csv, places the rows of the *.csv file in a two dimensional array, and then prints on item out of the array and then prints a row of the array. #!/usr/bin/perl use strict; use warnings; open(CSV, $ARGV[0]) || die("Cannot open the $ARGV[0] file: $!"); my @row; my @table; while(<CSV>) { @row = split(/\s*,\s*/, $_); push(@table, @row); } close CSV || die $!; foreach my $element ( @{ $table[0] } ) { print $element, "\n"; } print "$table[0][1]\n"; When I run this script I receive the following error and nothing prints: Can't use string ("1") as an ARRAY ref while "strict refs" in use at ./scripts.pl line 16. I have looked in a number of other forums and am still not sure how to fix this issue. Can anyone help me fix this script?

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Using perl to split a line that may contain whitespace

- by Tommy Fisk

Okay, so I'm using perl to read in a file that contains some general configuration data. This data is organized into headers based on what they mean. An example follows: [vars] # This is how we define a variable! $var = 10; $str = "Hello thar!"; # This section contains flags which can be used to modify module behavior # All modules read this file and if they understand any of the flags, use them [flags] Verbose = true; # Notice the errant whitespace! [path] WinPath = default; # Keyword which loads the standard PATH as defined by the operating system. Append with additonal values. LinuxPath = default; Goal: Using the first line as an example "$var = 10;", I'd like to use the split function in perl to create an array that contains the characters "$var" and "10" as elements. Using another line as an example: Verbose = true; # Should become [Verbose, true] aka no whitespace is present This is needed because I will be outputting these values to a new file (which a different piece of C++ code will read) to instantiate dictionary objects. Just to give you a little taste of what it might look like (just making it up as I go along): define new dictionary name: [flags] # Start defining keys => values new key name: Verbose new value val: 10 # End dictionary Oh, and here is the code I currently have along with what it is doing (incorrectly): sub makeref($) { my @line = (split (/=/)); # Produces ["Verbose", " true"]; }

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Perl: POST request how?

- by Peterim

Unfortunately, I'm not familiar with Perl, so asking here. Actually I'm using FCGI with Perl. I need to 1. accept a POST request - 2. send it via POST to another url - 3. get results - 4. return results to the first POST request (4 steps). To accept a POST request (step 1) I use the following peace of code (found it somewhere in the Internet): $ENV{'REQUEST_METHOD'} =~ tr/a-z/A-Z/; if ($ENV{'REQUEST_METHOD'} eq "POST") { read(STDIN, $buffer, $ENV{'CONTENT_LENGTH'}); } else { print ("some error"); } @pairs = split(/&/, $buffer); foreach $pair (@pairs) { ($name, $value) = split(/=/, $pair); $value =~ tr/+/ /; $value =~ s/%(..)/pack("C", hex($1))/eg; $FORM{$name} = $value; } The content of $name (it's a string) is the result of the first step. Now I need to send $name via POST request to some_url (step 2) which returns me another result (step 3), which I have to return as a result to the very first POST request (step 4). Any help with this would be greatly appreciated. Thank you.

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Perl : package using problem.

- by pavun_cool

Hi All.. Normally when I am writing the perl program . I used to include following package . use strict ; use warnings ; use Data::Dumper ; Now , I want like this, I will not include all this package for every program . for that I will have these all package in my own package. like following. my_packages.pm package my_packages ; { use strict ; use warnings ; use Data::Dumper; } 1; So, that if I add my_packages.pm in perl program , it needs have all above packages . Actually I have done this experimentation . But I am not able get this things . which means when I am using my_packages . I am not able get the functionality of "use strict, use warnings , use Data::Dumper ". Someone help me out of this problem.....

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Printing out this week's dates in perl

- by ABach

Hi folks, I have the following loop to calculate the dates of the current week and print them out. It works, but I am swimming in the amount of date/time possibilities in perl and want to get your opinion on whether there is a better way. Here's the code I've written: #!/usr/bin/env perl use warnings; use strict; use DateTime; # Calculate numeric value of today and the # target day (Monday = 1, Sunday = 7); the # target, in this case, is Monday, since that's # when I want the week to start my $today_dt = DateTime->now; my $today = $today_dt->day_of_week; my $target = 1; # Create DateTime copies to act as the "bookends" # for the date range my ($start, $end) = ($today_dt->clone(), $today_dt->clone()); if ($today == $target) { # If today is the target, "start" is already set; # we simply need to set the end date $end->add( days => 6 ); } else { # Otherwise, we calculate the Monday preceeding today # and the Sunday following today my $delta = ($target - $today + 7) % 7; $start->add( days => $delta - 7 ); $end->add( days => $delta - 1 ); } # I clone the DateTime object again because, for some reason, # I'm wary of using $start directly... my $cur_date = $start->clone(); while ($cur_date <= $end) { my $date_ymd = $cur_date->ymd; print "$date_ymd\n"; $cur_date->add( days => 1 ); } As mentioned, this works - but is it the quickest/most efficient/etc.? I'm guessing that quickness and efficiency may not necessarily go together, but your feedback is very appreciated.

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Perl, regex, extract data from a line

- by perlnoob

Im trying to extract part of a line with perl use strict; use warnings; # Set path for my.txt and extract datadir my @myfile = "C:\backups\MySQL\my.txt"; my @datadir = ""; open READMYFILE, @myfile or die "Error, my.txt not found.\n"; while (<READMYFILE>) { # Read file and extract DataDir path if (/C:\backups/gi) { push @datadir, $_; } } # ensure the path was found print @datadir . " \n"; Basically at first im trying to set the location of the my.txt file. Next im trying to read it and pull part of the line with regex. The error Im getting is: Unrecognized escape \m passed through at 1130.pl line 17. I took a look at http://stackoverflow.com/questions/1040657/how-can-i-grab-multiple-lines-after-a-matching-line-in-perl to get an idea of how to read a file and match a line within it, however im not 100% sure I'm doing this right or in the best way. I also seem to produce the error: Error, my.txt not found. But the file does exist in the folder C:\backups\MySQL\

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Opening a Unicode file with Perl

- by Jaco Pretorius

I'm using osql to run several sql scripts against a database and then I need to look at the results file to check if any errors occurred. The problem is that perl doesn't seem to like the fact that the results files are unicode. I wrote a little test script to test it and the output comes out all warbled. $file = shift; open OUTPUT, $file or die "Can't open $file: $!\n"; while (<OUTPUT>) { print $_; if (/Invalid|invalid|Cannot|cannot/) { push(@invalids, $file); print "invalid file - $inputfile - schedule for retry\n"; last; } } Any ideas? I've tried decoding using decode_utf8 but it makes no difference. I've also tried to set the encoding when opening the file. I think the problem might be that osql puts the result file in UTF-16 format, but I'm not sure. When I open the file in textpad it just tells me 'Unicode'. Edit: Using perl v5.8.8

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Counting total sum of each value in one column w.r.t another in Perl

- by sfactor

I have tab delimited data with multiple columns. I have OS names in column 31 and data bytes in columns 6 and 7. What I want to do is count the total volume of each unique OS. So, I did something in Perl like this: #!/usr/bin/perl use warnings; my @hhfilelist = glob "*.txt"; my %count = (); for my $f (@hhfilelist) { open F, $f || die "Cannot open $f: $!"; while (<F>) { chomp; my @line = split /\t/; # counting volumes in col 6 and 7 for 31 $count{$line[30]} = $line[5] + $line[6]; } close (F); } my $w = 0; foreach $w (sort keys %count) { print "$w\t$count{$w}\n"; } So, the result would be something like Windows 100000 Linux 5000 Mac OSX 15000 Android 2000 But there seems to be some error in this code because the resulting values I get aren't as expected. What am I doing wrong?

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Perl : get substring which matches refex error

- by Michael Mao

Hi all: I am very new to Perl, so please bear with my simple question: Here is the sample output: Most successful agents in the Emarket climate are (in order of success): 1. agent10896761 ($-8008) 2. flightsandroomsonly ($-10102) 3. agent10479475hv ($-10663) Most successful agents in the Emarket climate are (in order of success): 1. agent10896761 ($-7142) 2. agent10479475hv ($-8982) 3. flightsandroomsonly ($-9124) I am interested only in agent names as well as their corresponding balances, so I am hoping to get the following output: agent10896761 -8008 flightsandroomsonly -10102 agent10479475hv -10663 agent10896761 -7142 agent10479475hv -8982 flightsandroomsonly -9124 For later processes. This is the code I've got so far: #!/usr/bin/perl -w open(MYINPUTFILE, $ARGV[0]); while(<MYINPUTFILE>) { my($line) = $_; chomp($line); # regex match test if($line =~ m/agent10479475/) { if($line =~ m/($-[0-9]+)/) { print "$1\n"; } } if($line =~ m/flightsandroomsonly/) { print "$line\n"; } } The second regex match has nothing wrong, 'cause that is printing out the whole line. However, for the first regex match, I've got some other output such like: $ ./compareResults.pl 3.txt 2. flightsandroomsonly ($-10102) 0479475 0479475 3. flightsandroomsonly ($-9124) 1. flightsandroomsonly ($-8053) 0479475 1. flightsandroomsonly ($-6126) 0479475 If I "escape" the braces like this if($line =~ m/\($-[0-9]+\)/) { print "$1\n"; } Then there is never a match for the first regex... So I stuck with a problem of making that particular regex work. Any hints for this? Many thanks in advance.

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Perl program for extracting the functions alone in a Ruby file

- by thillaiselvan

Hai all, I am having the following Ruby program. puts "hai" def mult(a,b) a * b end puts "hello" def getCostAndMpg cost = 30000 # some fancy db calls go here mpg = 30 return cost,mpg end AltimaCost, AltimaMpg = getCostAndMpg puts "AltimaCost = #{AltimaCost}, AltimaMpg = {AltimaMpg}" I have written a perl script which will extract the functions alone in a Ruby file as follows while (<DATA>){ print if ( /def/ .. /end/ ); } Here the <DATA> is reading from the ruby file. So perl prograam produces the following output. def mult(a,b) a * b end def getCostAndMpg cost = 30000 # some fancy db calls go here mpg = 30 return cost,mpg end But, if the function is having block of statements, say for example it is having an if condition testing block means then it is not working. It is taking only up to the "end" of "if" block. And it is not taking up to the "end" of the function. So kindly provide solutions for me. Example: def function if x > 2 puts "x is greater than 2" elsif x <= 2 and x!=0 puts "x is 1" else puts "I can't guess the number" end #----- My code parsing only up to this end Thanks in Advance!

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Pull specific information from a long list with Perl

- by melignus

The file that I've got to work with here is the result of an LDAP extraction but I need to ultimately get the information formatted over to something that a spreadsheet can use. So, the data is as follows: DataDataDataDataDataDataDataDataDataDataDataDataDataDataDataData DataDataDataDataDataDataDataDataDataDataDataDataDataDataDataData displayName: John Doe name: ##userName DataDataDataDataDataDataDataDataDataDataDataDataDataDataDataData DataDataDataDataDataDataDataDataDataDataDataDataDataDataDataData displayName: Jane Doe name: ##userName DataDataDataDataDataDataDataDataDataDataDataDataDataDataDataData DataDataDataDataDataDataDataDataDataDataDataDataDataDataDataData displayName: Ted Doe name: ##userName The format that I need to export to is: firstName lastName userName firstName lastName userName firstName lastName userName Where the spaces are tabs so I can then impor that file into a database. I have experience doing this in VBScript but I'm trying to switch over to using Perl for as much server administration as possible. I'm not sure on the syntax for what I want which is basically while not endoffile{ detect "displayName: " & $firstName & " " & $lastName detect "name: ##" & $userName write $firstName tab $lastName tab $userName to file } Also if someone could point me to a resource specifically on the text parsing syntax that Perl uses, I'd be very grateful. Most of the resources that I've come across haven't been very helpful.

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how to store a file handle in perl class

- by Haiyuan Zhang

please look at the following code first. #! /usr/bin/perl package foo; sub new { my $pkg = shift; my $self = {}; my $self->{_fd} = undef; bless $self, $pkg; return $self; } sub Setfd { my $self = shift; my $fd = shift; $self_->{_fd} = $fd; } sub write { my $self = shift; print $self->{_fd} "hello word"; } my $foo = new foo; My intention is to store a file handle within a class using hash. the file handle is undefined at first, but can be initilized afterwards by calling Setfd function. then write can be called to actually write string "hello word" to a file indicated by the file handle, supposed that the file handle is the result of a success "write" open. but, perl compiler just complains that there are syntax error in the "print" line. can anyone of you tells me what's wrong here? thanks in advance.

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User input in Perl with IO::Socket

- by David

I am trying to make a perl program which allows a user to input the host and the port number of a foreign host to connect to using IO::Socket. It allows me to run the program and input a host and a port but it never connects and says "Could not connect to [host] at c:\users\USER\Documents\code\perl\sql.pl line 18, line 2." What am i doing wrong with this code shown below? And also, how can i have input validation on my host, which can either be a host name or an ip address? Thanks a bunch! Code Below use IO::Socket print "Host to connect to: "; chomp ($host = <STDIN>); print "Port to connect with: "; chomp ($port = <STDIN>); while(($port > 65535) || ($port <= 0)){ print "Port to connect with [Port > 0 < 65535] : "; chomp ($port = <STDIN>); } print "\nConnecting to host $host on port $port\n"; $socket = new IO::Socket::INET ( LocalHost => '$host', LocalPort => '$port', Proto => 'tcp', Listen => 5, Reuse => 1 ); die "Could not connect to $host";

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excel graphs using perl

- by user1822725

i amfacing problem when i ran the script its giving error like Can't locate object method "add_chart" via package "Spreadsheet::WriteExcel" at chart_column.pl line 33. May i know what is the problem here? And i am using perl, v5.8.5 built for x86_64-linux. #!/usr/bin/perl -w ############################################################################### # # A simple demo of Column charts in Spreadsheet::WriteExcel. # # reverse('©'), December 2009, John McNamara, [email protected] # use strict; use Spreadsheet::WriteExcel; my $workbook = Spreadsheet::WriteExcel->new( 'chart_column.xls' ); my $worksheet = $workbook->add_worksheet(); my $bold = $workbook->add_format( bold => 1 ); # Add the worksheet data that the charts will refer to. my $headings = [ 'Category', 'Values 1', 'Values 2' ]; my $data = [ [ 2, 3, 4, 5, 6, 7 ], [ 1, 4, 5, 2, 1, 5 ], [ 3, 6, 7, 5, 4, 3 ], ]; $worksheet->write( 'A1', $headings, $bold ); $worksheet->write( 'A2', $data ); ############################################################################### # # Example 1. A minimal chart. # my $chart1 = $workbook->add_chart( type => 'column' ); # Add values only. Use the default categories. $chart1->add_series( values => '=Sheet1!$B$2:$B$7' ); # Insert the chart into the main worksheet. $worksheet->insert_chart( 'E2', $chart1 );

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Server Push CGI Perl Problem writing the JPEG image

- by Jujjuru

I am a beginner in Perl CGI etc. I was experimenting with server-push concept with a piece of perl code. It is supposed to send a jpeg image to the client every 3 seconds. Unfortunately nothing seems to work. Can somebody help identify the problem? Here is the code.... use strict; # turn off io buffering $|=1; print "Content-type: multipart/x-mixed-replace;"; print "boundary=magicalboundarystring\n\n"; print "--magicalboundarystring\n"; #list the jpg images my(@file_list) = glob "*.jpg"; my($file) = ""; foreach $file(@file_list ) { open FILE,">", $file or die "Cannot open file $file: $!"; print "Content-type: image/jpeg\n\n"; while ( <FILE> ) { print "$_"; } close FILE; print "\n--magicalboundarystring\n"; sleep 3; next; } EDIT: added turn off i/o buffering, added "use strict" and "@file_list", "$file" are made local

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how to append a string to next line in perl

- by tprayush

hi all , i have a requirement like this.. this just a sample script... $ cat test.sh #!/bin/bash perl -e ' open(IN,"addrss"); open(out,">>addrss"); @newval; while (<IN>) { @col_val=split(/:/); if ($.==1) { for($i=0;$i<=$#col_val;$i++) { print("Enter value for $col_val[$i] : "); chop($newval[$i]=<STDIN>); } $str=join(":"); $_="$str" print OUT; } else { exit 0; } } close(IN); close(OUT); ' when i run this scipt... $ ./test.sh Enter value for NAME : abc Enter value for ADDRESS : asff35 Enter value for STATE : XYZ Enter value for CITY : EIDHFF Enter value for CONTACT : 234656758 $ cat addrss NAME:ADDRESS:STATE:CITY:CONTACT abc:asff35:XYZ:EIDHFF:234656758 when ran it second time $ cat addrss NAME:ADDRESS:STATE:CITY:CONTACT abc:asff35:XYZ:EIDHFF:234656758ioret:56fgdh:ghdgh:afdfg:987643221 ## it is appended in the same line... i want it to be added to the next line..... NOTE: i want to do this by explitly using the filehandles in perl....and not with redirection operators in shell. please help me!!!

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Define an empty array in Perl class new()

- by Laimoncijus

Hi, I am just beginner with Perl, so if it sounds stupid - sorry for that :) My problem is - I am trying to write a class, which has an empty array, defined in constructor of a class. So I am doing this like this: package MyClass; use strict; sub new { my ($C) = @_; my $self = { items => () }; bless $self, ref $C || $C; } sub get { return $_[0]->{items}; } 1; Later I am testing my class with simple script: use strict; use Data::Dumper; use MyClass; my $o = MyClass->new(); my @items = $o->get(); print "length = ", scalar(@items), "\n", Dumper(@items); And while running the script I get following: $ perl my_test.pl length = 1 $VAR1 = undef; Why am I doing wrong what causes that I get my items array filled with undef? Maybe someone could show me example how the class would need to be defined so I would not get any default values in my array? Thanks!

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Perl, strings, floats, unit testing and regexps!

- by Chris R

OK, as a preface this question potentially is 'stupider' than my normal level of question - however this problem has been annoying me for the last few days so I'll ask it anyway. I'll give a mock example of what my problem is so I can hope to generalize it to my current problem. #!/usr/bin/perl -w use strict; use Test::More 'no_plan'; my $fruit_string = 'Apples cost $1.50'; my ($fruit, $price) = $fruit_string =~ /(\w+)s cost \$(\d+\.\d+)/; # $price += 0; # Uncomment for Great Success is ($price, 1.50, 'Great Success'); Now when this is run I get the message # Failed test 'Great Success' # got: '1.50' # expected: '1.5' To make the test work - I either uncomment the commented line, or use is ($price, '1.50', 'Great Success'). Both options do not work for me - I'm testing a huge amount of nested data using Test::Deep and cmp_deeply. My question is, how can you extract a double from a regexp then use it immediately as a double - or if there is a better way altogether let me know - and feel free to tell me to take up gardening or something lol, learning Perl is hard.

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Firing through HTTP a Perl script for sending signals to daemons

- by Eric Fortis

Hello guys, I'm using apache2 on Ubuntu. I have a Perl script which basically read the files names of a directory, then rewrites a text file, then sends a signal to a daemon. How can this be done, as secure as possible through a web-page? Actually I can run the code below, but not if I remove the comments. I'm looking for advise considering: Using HTTP Requests? How about Apache file permissions on the directory shown in code? Is htaccess enough to enable user/pass access to the cgi? Should I use a database instead of writing to a file and run a cron querying the db with permission granted to write and send the signal? Granting as less permissions as possible to the webserver. Should I set a VPN? #!/usr/bin/perl -wT use strict; use CGI; #@fileList = </home/user/*>; #read a directory listing my $query = CGI->new(); print $query->header( "text/html" ), $query->p( "FirstFileNameInArray" ), #$query->p( $fileList[0] ), #output the first file in directory $query->end_html;

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How to stop input in Perl?

- by user1472747

First time poster and part time perl noobie. I'm making a reflex game. Here's the output - __________________________________________________________________________ Reflex game initiated. Press ENTER to begin the game, and then press ENTER after the asterisks are printed to measure your reflexes!. ************************* Your result: 0.285606 seconds. logout [Process completed] __________________________________________________________________________ There's one small problem though - There's 0-10 seconds (based on a random variable) after you press enter to start the game and before the stars are printed. During that time, if the player presses ENTER, it's logged as their reflex time. So I need a way to stop my code from reading their ENTER button before the stars are printed. The code - #!/usr/bin/perl use Time::HiRes qw(sleep); use Time::HiRes qw(gettimeofday); #random delay variable $random_number = rand(); print "Reflex game initiated. Press ENTER to begin the game, and then press ENTER after the asterisks are printed to measure your reflexes!.\n"; #begin button $begin = <>; #waits x milliseconds sleep(10*$random_number); #pre-game $start = [ Time::HiRes::gettimeofday() ]; print "\n****************************\n"; #user presses enter $stop = <>; #post game $elapsed = Time::HiRes::tv_interval($start); #delay time print print "Your result: ".$elapsed." seconds.\n";

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Can't post with Perl's Net::Blogger

- by Ovid

I'm trying to automatically post to blogger using Perl's Net::Blogger but it keeps returning false and not posting. The main portion of my code looks like this: use Net::Blogger; my $blogger = Net::Blogger->new({ debug => 1, appkey => '0123456789ABCDEF', # doesn't matter? blogid => $blogid, username => $username, password => $password, }); say 'got to here'; my $result = $blogger->newPost({ postbody => \'<p>This is text</p><hr/><p><strong>Whee!</strong></p>', publish => 1, }); say 'done posting'; use Data::Dumper; print Dumper($result); Sure enough, $result is 0 and in checking the blog, nothing has been posted. The error I'm getting when I enable debugging is: Element '' can't be allowed in valid XML message. Died. at /Library/Perl/5.10.1/SOAP/Lite.pm line 1410. What am I doing wrong? If you can suggest an alternative to Net::Blogger, that would be fine.

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how to install a file handle in perl class

- by Haiyuan Zhang

please looku up the following code first. #! /usr/bin/perl package foo; sub new { my $pkg = shift; my $self = {}; my $self->{_fd} = undef; bless $self, $pkg; return $self; } sub Setfd { my $self = shift; my $fd = shift; $self_->{_fd} = $fd; } sub write { my $self = shift; print $self->{_fd} "hello word"; } my $foo = new foo; My intention is to store a file handle within a class using hash. the file handle is undefined at first, but can be initilized afterwards by calling Setfd function. then write can be called to actually write string "hello word" to a file indicated by the file handle, supposed that the file handle is the result of a success "write" open. but, perl compiler just complains that there are syntax error in the "print" line. can anyone of you tells me what's wrong here? thanks in advance.

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How to end a thread in perl

- by user1672190

I am new to perl and i have a question about perl thread. I am trying to create a new thread to check if the running function is timed out, and my way of doing it is as below. Logic is 1.create a new thread 2.run the main function and see if it is timed out, if ture, kill it Sample code: $exit_tread = false; # a flag to make sure timeout thread will run my $thr_timeout = threads->new( \&timeout ); execute main function here; $exit_thread = true # set the flag to true to force thread ends $thr_timeout->join(); #wait for the timeout thread ends Code of timeout function sub timeout { $timeout = false; my $start_time = time(); while (!$exit_thread) { sleep(1); last if (main function is executed); if (time() - $start_time >= configured time ) { logmsg "process is killed as request timed out"; _kill_remote_process(); $timeout = true; last; } } } now the code is running as i expected, but i am just not very clear if the code $exit_thread = true works because there is a "last" at the end of while loop. Can anybody give me a answer? Thanks

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Meaning of NEXT in Linked List creation in perl

- by seleniumnewbie

So I am trying to learn Linked Lists using Perl. I am reading "Mastering Algorithms with Perl" by Job Orwant. In the book he explains how to create a linked list I understand most of it, but I just simply fail to understand the command/index/key NEXT in the second last line of the code snippet. $list=undef; $tail=\$list; foreach (1..5){ my $node = [undef, $_ * $_]; $$tail = $node; $tail = \${$node->[NEXT]}; # The NEXT on this line? } What is he trying to do there? Isn $node a scalar, which stores the address of the unnamed array. Also even if we are de-referencing $node, should we not refer to the individual elements by an index number example (0,1). If we do use "NEXT" as a key, is $node a reference to a hash? I am very confused. Something in plain English will be highly appreciated.

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