Here is how you can use perl to read from one file and write to another: open(FILEREAD, “< file.read.name”); open(FILEWRITE, “> file.write.name”); while (<FILEREAD>){ print FILEWRITE; } close FILEWRITE; close FILEREAD; This will assign the file handle FILEREAD to the file file.read.name and start reading it in line by line in the while loop. The […]

In this article we created archived log files. Well, it would be nice to have a way to grab the daily log files off of an HTML document. Here is a perl script that does this: #!/usr/bin/perl for ($month=1;$month<13;$month++){ system(“cal -1 $month 2003 > calout”); open(CAL, “< calout”); print “<pre>”; while (<CAL>){ $last=$_; if($last=~/[A-Z]/){ if($last=~/\d\d\d\d/){ […]

I often have to snag the output of system commands and parse them with perl. Well, Urbana turned me on to a method of grabbing the output that is much easier than directing the output of the system command to a file and re-opening the file. Just use a pipe: #!/usr/bin/perl open (PINGTEST, “/bin/ping -c […]

One problem with the default install of the CPAN shell is that if you need passive FTP to get through your firewall, the CPAN shell won’t work. Here is the behavior: . . . Invalid PORT. Retrying. –12:26:05– ftp://ftp.perl.org/pub/CPAN/authors/01mailrc.txt.gz (try: 8) => `-‘ Connecting to ftp.perl.org[192.35.244.50]:21… connected. Logging in as anonymous … Logged in! ==> […]

Agatha had some complaints about her chicken cam. People weren’t seeing enough chicken booty. A quick and easy way to do this is to use Perl: while(6 ne 9){ for($c=1;$c<11;$c++){ system(“scp root\@crackers:/chickenpicture.jpg /home/u-1/chickencam”); system(“scp /home/u-1/chickencam/chickenpicture.jpg root\@signalq.com:/web/path/here/”); system(“scp /home/u-1/chickencam/chickenpicture.jpg root\@signalq.com:/web/path/here/archive/chickenpicture”.$c.”.jpg”); sleep 300; } } This way, the chicken cam cycles through. The only tricky part is […]

In this article I show how to use Perl to extract keywords from a text file, create an index of these keywords, and reassemble the text in a simplified way. This will give you compression, as well as control over stored data. I used The Snow Queen with the simplified character set of the Odyssey […]

In this article I showed how to extract keywords from a text file to create an index, and I reassembled the text again from the compressed file. In this article, I render the compressed file with a limited character set. Here is the code: %found = (); %index= (); $i=1; # this will grab 196 […]

You can match hex characters with \x. Just put \x before the hexadecimal number. For instance, if you wish to replace all backspace characters with nothing, use this: perl -pi -e “s|\x08||g” file.txt

One cool thing you can do with perl is write a filter. We often tail various log files, but just want to know about specific bits. If we want to see more, we can look at the actual logs; however, for the purposes of the current activity, we don’t need much information. Say your logs […]

There are restrictions on the crypt-des.ppd module that make it a rare beastie to find. When you try and install via ppm: ppm> install net-snmp Error: PPD for ‘Crypt-DES.ppd’ could not be found. After some searching, we did find the module at soulcage.net. The site seems legit, but do your own homework. To add the […]

To send a command via TCP with Perl, you can use IO::Socket::INET: use IO::Socket; my $sock = new IO::Socket::INET ( PeerAddr => ‘localhost’, PeerPort => ‘1001’, Proto => ‘tcp’, ); die “Error: $!\n” unless $sock; print $sock “commandtoexecute\n”; close($sock); This will send the command commandtoexecute to port 1001 on localhost or complain that there is […]

Let’s say that you have a bunch of references to files that take the format IMGblahx.JPG, but all of the files are actually IMGblahx.jpg. An example file would be named IMG_1807.JPG. To change all of the references to IMGblahx.JPG to IMGblahx.jpg, use this one line perl script: $ perl -pi -e “s|(IMG……)JPG|\$1jpg|g” * Put an […]