Assume a nested hash structure %old_hash .. my %old_hash; $old_hash{"foo"}{"bar"}{"zonk"} = "hello"; .. which we want to "flatten" (sorry if that's the wrong terminology!) to a non-nested hash using the sub &flatten(...) so that .. my %h = &flatten(\%old_hash); die unless($h{"zonk"} eq "hello"); The following definition of &flatten...
I have a data that looks like this: 3 2 1 5 What I want to get is the "decreasing" cumulative of this data yielding 11 8 6 5 0 What is the compact way of doing that in Perl? ...
My static web pages are built from a huge bunch of templates which are inter-included using Template Toolkit's "import" and "include", so page.html looks like this: [% INCLUDE top %] [% IMPORT middle %] Then top might have even more files included. I have very many of these files, and they have to be run through to create the web pag...
Hello! How could I implement in this piece of code a timeout: if the "hwinfo --usb"-command didn't return anything after a certain amount of time, ( stop the command and ) do a return or die from the sub _usb_device. #!/usr/bin/env perl use warnings; use strict; sub _usb_device { my @array; { local $/ = ""; @array = q...
I have two text files that contain columnar data of the variety position-value, sorted by position. Here is an example of the first file (file A): 100 1 101 1 102 0 103 2 104 1 ... Here is an example of the second file (B): 20 0 21 0 ... 100 2 101 1 192 3 193 1 ... Instead of reading one of the two files in...
I'm using Windows, and I would like to extract certain columns from a text file using a Perl, Python, batch etc. one-liner. On Unix I could do this: cut -d " " -f 1-3 <my file> How can I do this on Windows? ...
When I run perl, I get the warning: perl: warning: Setting locale failed. perl: warning: Please check that your locale settings: LANGUAGE = (unset), LC_ALL = (unset), LANG = "en_US.UTF-8" are supported and installed on your system. perl: warning: Falling back to the standard locale ("C"). Any ideas on how to fix it? ...
I've just started diving in to the crazy world that is perl and have come across a problem that I cannot seem to wrap my head around. Specifically I need to be able to convert from one hash structure to another, that uses the keys/values as the new hashes keys/values. An example: Input hash: my %original_hash = ( first_key => ...
Are there any services similar to codepad that will allow you to test Perl constructs on old versions of perl? Ideally, a system where you could enter an expression and it will tell you the oldest version of perl that it will work with. Of course it's possible to use CPANTS for this, but that seems like an abuse of the service (if only...
I am using Devel::LeakTrace::Fast to debug a memory leak in a perl script designed as a daemon which runs an infinite loop with sleeps until interrupted. I am having some trouble both reading the output and finding documentation to help me understand the output. The perldoc doesn't contain much information on the output. Most of it ma...
Say I have a resource (e.g. a filehandle or network socket) which has to be freed: open my $fh, "<", "filename" or die "Couldn't open filename: $!"; process($fh); close $fh or die "Couldn't close filename: $!"; Suppose that process might die. Then the code block exits early, and $fh doesn't get closed. I could explicitly check for er...
Using the Perl module Net::Telnet, how do you send an arrow key to a telnet session so that it would be the same thing as a user pressing the down key on the keyboard? use Net::Telnet; my $t = new Net::Telnet(); my $down_key=?; #How do you send a down key in a telnet session? t->print($down_key); This list of VT102 codes says that cur...
I have a hash in which I store the products a customer buys (%orders). It uses the product code as key and has a reference to an array with the other info as value. At the end of the program, I have to rewrite the inventory to the updated version (i.e. subtract the quantity of the bought items) This is how I do rewrite the inventory: ...
I want a Perl regular expression that will match duplicated words in a string. Given the following input: $str = "Thus joyful Troy Troy maintained the the watch of night..." I would like the following output: Thus joyful [Troy Troy] maintained [the the] watch of night... ...
This is the first time I have manipulated hashes and arrays in this way -- and it is working. Basically, for every key there are multiple values that I want to record and then print out in the form "key --> value --> value --> val..." My code is as follows. I am surprised that it works, so concerned that it works "by mistake". Is this t...
I have written following in index.pl which is the C:\xampp\htdocs\perl folder: #!/usr/bin/perl print "<html>"; print "<h2>PERL IT!</h2>"; print "this is some text that should get displyed in browser"; print "</html>"; When I browse to http://localhost:88/perl/ the above HTML doesn't get displayed (I have tried in IE FF and chrome). ...
I'm trying to move a file but I want to ensure that it exists before I do so. What's the simplest way to do this in Perl? My code is like this. I looked up the open command, but I am not sure it is the simplest way or not. if #Parser.exe exist in directory of Debug { move ("bin/Debug/Parser.exe","Parser.exe"); } elsif #Parser.e...
I got a package called 1.pm in that the constructor is calling a subroutine which is in the same package. Now, if some other classes say 2.pm is calling the constructor defined in 1.pm, how can I determine if the subroutine is called from 2.pm? ...
I've got a TCP socket which reads data. When an error occurs when reading the data, I return an undef (NULL) value. Errors can be caused by badly formatted messages or broken sockets. Can someone tell me if there is a specific function which returns the status of a socket? ...
My upload function looks like: sub Upload_File{ my ($file, $mime, $description) = @_; my $file_name = param('filename'); my $data; $file = UnTaint($file); if ($mime =~ /text/) { sysopen(VAULT, "$path/$file", O_RDWR | O_EXCL | O_CREAT | O_TEXT) or die "couldn't create $file for R/W: $!\n"; } else { sy...