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<div class="MsoNormal" style="line-height: normal; mso-margin-bottom-alt: auto; mso-margin-top-alt: auto; mso-outline-level: 1;">
<b><span lang="EN-IN" style="font-family: "Times New Roman","serif"; font-size: 24.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN; mso-font-kerning: 18.0pt;">PERL - File Handling</span></b></div>
<div class="MsoNormal" style="line-height: normal; mso-margin-bottom-alt: auto; mso-margin-top-alt: auto;">
<span lang="EN-IN" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;">Now we
shift gears as we introduce file handling. In PERL files are given a name, a
handle, basically another way of saying alias. All input and output with files
is achieved through filehandling. Filehandles are also a means by one program
may communicate with another program.</span></div>
<h1>
<span lang="EN-IN">PERL - Assigning Handles</span></h1>
<span lang="EN-IN">A filehandle is nothing more than a nickname for the files
you intend to use in your PERL scripts and programs. A handle is a temporary
name assigned to a file. A great filehandle is an abreviated version of the
filename. The example below illustrates how you will use a file handle in your
PERL code.</span><br />
<h2>
<span lang="EN-IN">PERL Code:</span></h2>
<pre><span lang="EN-IN">#!/usr/bin/perl</span></pre>
<pre><span lang="EN-IN"> </span></pre>
<pre><span lang="EN-IN">print "content-type: text/html \n\n"; #The header</span></pre>
<pre><span lang="EN-IN">$FilePath = "home/html/myhtml.html"</span></pre>
<pre><span lang="EN-IN">sysopen(<span style="color: red;">HANDLE</span>, $FilePath, O_RDWR);</span></pre>
<pre><span lang="EN-IN">printf <span style="color: red;">HANDLE</span> "Welcome to MYSITE!";</span></pre>
<pre><span lang="EN-IN">close (<span style="color: red;">HANDLE</span>);</span></pre>
<h1>
<span lang="EN-IN">PERL - Files and the die Function</span></h1>
<span lang="EN-IN">The <i>die</i> function exists in several programming
languages. It is used to kill your scripts and helps pinpoint where/if your
code is failing. We use this function as follows.</span><br />
<h2>
<span lang="EN-IN">PERL Code:</span></h2>
<pre><span lang="EN-IN">#!/usr/bin/perl</span></pre>
<pre><span lang="EN-IN"> </span></pre>
<pre><span lang="EN-IN">print "content-type: text/html \n\n"; #The header</span></pre>
<pre><span lang="EN-IN"> </span></pre>
<pre><span lang="EN-IN">$filepath = "myhtml.html";</span></pre>
<pre><span lang="EN-IN"> </span></pre>
<pre><span lang="EN-IN" style="color: red;">sysopen (HTML, '$filepath', O_RDWR|O_EXCL|O_CREAT, 0755) or die "$filepath cannot be opened.";</span></pre>
<pre><span lang="EN-IN">printf HTML "<html>\n"; </span></pre>
<pre><span lang="EN-IN">printf HTML "<head>\n"; </span></pre>
<pre><span lang="EN-IN">printf HTML "<title>My Home Page</title>"; </span></pre>
<pre><span lang="EN-IN">printf HTML "</head>\n"; </span></pre>
<pre><span lang="EN-IN">printf HTML "<body>\n"; </span></pre>
<pre><span lang="EN-IN">printf HTML "<p align='center'>Here we have an HTML </span></pre>
<pre><span lang="EN-IN">page with a paragraph.</p>";</span></pre>
<pre><span lang="EN-IN">printf HTML "</body>\n"; </span></pre>
<pre><span lang="EN-IN">printf HTML "</html>\n"; </span></pre>
<pre><span lang="EN-IN">close (HTML);</span></pre>
<span lang="EN-IN">Now if for some reason PERL is unable to open or create our
file, we will be told. It is good practice to use the die function and we will
be using it more as we dive deeper into file handling.</span><br />
<h1>
<span lang="EN-IN">Perl - File Open</span></h1>
<span lang="EN-IN">Files are opened using the <i>open</i> and <i>sysopen</i>
function. Nothing fancy here at all. Either function may be passed up to 4
arguments, the first is always the file handle discussed earlier, then our file
name also known as a URL or filepath, flags, and finally any permissions to be
granted to this file.</span><br />
<span lang="EN-IN">When opening files as a programmer, there will generally be
one of three goals in mind, file creation, appending files, or trunicating
files.</span><br />
<div class="MsoNormal">
<b><span lang="EN-IN">Create:</span></b></div>
<div class="MsoNormal">
<span lang="EN-IN">Checks to see if the file exists, if not,
perl creates a new file. </span></div>
<div class="MsoNormal">
<b><span lang="EN-IN">Append:</span></b></div>
<div class="MsoNormal">
<span lang="EN-IN">Sets the pointer to the end of the file,
all output following will be added onto the tail end of the file. </span></div>
<div class="MsoNormal">
<b><span lang="EN-IN">Truncate:</span></b></div>
<div class="MsoNormal">
<span lang="EN-IN">Overwrites your existing file with a new
one, this means all data in the old file will be lost. </span></div>
<h1>
<span lang="EN-IN">PERL - Open a File</span></h1>
<span lang="EN-IN">The following example will open a previously saved HTML
document.</span><br />
<h2>
<span lang="EN-IN">PERL Code:</span></h2>
<pre><span lang="EN-IN">#!/usr/bin/perl</span></pre>
<pre><span lang="EN-IN"> </span></pre>
<pre><span lang="EN-IN">print "content-type: text/html \n\n"; #The header</span></pre>
<pre><span lang="EN-IN"> </span></pre>
<pre><span lang="EN-IN">$FH = "filehandle";</span></pre>
<pre><span lang="EN-IN">$FilePath = "myhtml.html";</span></pre>
<pre><span lang="EN-IN"> </span></pre>
<pre><span lang="EN-IN">open(FH, $FilePath, <i>permissions</i>);</span></pre>
<pre><span lang="EN-IN">or</span></pre>
<pre><span lang="EN-IN">sysopen(FH, $FileName, <i>permission</i>);</span></pre>
<span lang="EN-IN">Files with special characters or unusual names are best
opened by first declaring the URL as a variable. This method removes any
confusion that might occur as PERL tries to interpret the code. Tildas in
filenames however require a brief character substitution step before they can
be placed into your open statements.</span><br />
<h1>
<span lang="EN-IN">PERL - File Permissions</span></h1>
<span lang="EN-IN">File permissions are crucial to file security and function.
For instance, in order to function, a PERL file (.pl) must have executable file
permissions in order to function on your web server. Also, you may not want all
of your HTML files to be set to allow others to write to them or over them.
Here's a listing of what to pass to the <i>open</i> function when working with
file handles.</span><br />
<h2>
<span lang="EN-IN">Shorthand Flags:</span></h2>
<table border="0" cellpadding="0" class="MsoNormalTable" style="mso-cellspacing: 1.5pt; mso-yfti-tbllook: 1184;">
 <tbody>
<tr style="mso-yfti-firstrow: yes; mso-yfti-irow: 0;">
  <td style="padding: .75pt .75pt .75pt .75pt;"><div class="MsoNormal">
<b><span lang="EN-IN">Entities</span></b><span lang="EN-IN" style="font-size: 12.0pt; line-height: 115%;"></span></div>
</td>
  <td style="padding: .75pt .75pt .75pt .75pt;"><div class="MsoNormal">
<b><span lang="EN-IN">Definition</span></b><span lang="EN-IN" style="font-size: 12.0pt; line-height: 115%;"></span></div>
</td>
 </tr>
<tr style="mso-yfti-irow: 1;">
  <td style="padding: .75pt .75pt .75pt .75pt;"><div class="MsoNormal">
<span lang="EN-IN">< or r</span><span lang="EN-IN" style="font-size: 12.0pt; line-height: 115%;"></span></div>
</td>
  <td style="padding: .75pt .75pt .75pt .75pt;"><div class="MsoNormal">
<span lang="EN-IN">Read Only Access</span><span lang="EN-IN" style="font-size: 12.0pt; line-height: 115%;"></span></div>
</td>
 </tr>
<tr style="mso-yfti-irow: 2;">
  <td style="padding: .75pt .75pt .75pt .75pt;"><div class="MsoNormal">
<span lang="EN-IN">> or w</span><span lang="EN-IN" style="font-size: 12.0pt; line-height: 115%;"></span></div>
</td>
  <td style="padding: .75pt .75pt .75pt .75pt;"><div class="MsoNormal">
<span lang="EN-IN">Creates, Writes, and Truncates</span><span lang="EN-IN" style="font-size: 12.0pt; line-height: 115%;"></span></div>
</td>
 </tr>
<tr style="mso-yfti-irow: 3;">
  <td style="padding: .75pt .75pt .75pt .75pt;"><div class="MsoNormal">
<span lang="EN-IN">>> or a</span><span lang="EN-IN" style="font-size: 12.0pt; line-height: 115%;"></span></div>
</td>
  <td style="padding: .75pt .75pt .75pt .75pt;"><div class="MsoNormal">
<span lang="EN-IN">Writes, Appends, and Creates</span><span lang="EN-IN" style="font-size: 12.0pt; line-height: 115%;"></span></div>
</td>
 </tr>
<tr style="mso-yfti-irow: 4;">
  <td style="padding: .75pt .75pt .75pt .75pt;"><div class="MsoNormal">
<span lang="EN-IN" style="color: red;">+< or r+</span><span lang="EN-IN" style="font-size: 12.0pt; line-height: 115%;"></span></div>
</td>
  <td style="padding: .75pt .75pt .75pt .75pt;"><div class="MsoNormal">
<span lang="EN-IN" style="color: red;">Reads and Writes</span><span lang="EN-IN" style="font-size: 12.0pt; line-height: 115%;"></span></div>
</td>
 </tr>
<tr style="mso-yfti-irow: 5;">
  <td style="padding: .75pt .75pt .75pt .75pt;"><div class="MsoNormal">
<span lang="EN-IN">+> or w+</span><span lang="EN-IN" style="font-size: 12.0pt; line-height: 115%;"></span></div>
</td>
  <td style="padding: .75pt .75pt .75pt .75pt;"><div class="MsoNormal">
<span lang="EN-IN">Reads, Writes, Creates, and Truncates</span><span lang="EN-IN" style="font-size: 12.0pt; line-height: 115%;"></span></div>
</td>
 </tr>
<tr style="mso-yfti-irow: 6; mso-yfti-lastrow: yes;">
  <td style="padding: .75pt .75pt .75pt .75pt;"><div class="MsoNormal">
<span lang="EN-IN" style="color: red;">+>> or a+</span><span lang="EN-IN" style="font-size: 12.0pt; line-height: 115%;"></span></div>
</td>
  <td style="padding: .75pt .75pt .75pt .75pt;"><div class="MsoNormal">
<span lang="EN-IN" style="color: red;">Reads, Writes, Appends,
  and Creates</span><span lang="EN-IN" style="font-size: 12.0pt; line-height: 115%;"></span></div>
</td>
 </tr>
</tbody></table>
<h2>
<span lang="EN-IN">O_ Flags:</span></h2>
<table border="0" cellpadding="0" class="MsoNormalTable" style="mso-cellspacing: 1.5pt; mso-yfti-tbllook: 1184;">
 <tbody>
<tr style="mso-yfti-firstrow: yes; mso-yfti-irow: 0;">
  <td style="padding: .75pt .75pt .75pt .75pt;"><div class="MsoNormal">
<b><span lang="EN-IN">Value</span></b><span lang="EN-IN" style="font-size: 12.0pt; line-height: 115%;"></span></div>
</td>
  <td style="padding: .75pt .75pt .75pt .75pt;"><div class="MsoNormal">
<b><span lang="EN-IN">Definition</span></b><span lang="EN-IN" style="font-size: 12.0pt; line-height: 115%;"></span></div>
</td>
 </tr>
<tr style="mso-yfti-irow: 1;">
  <td style="padding: .75pt .75pt .75pt .75pt;"><div class="MsoNormal">
<span lang="EN-IN">O_RDWR</span><span lang="EN-IN" style="font-size: 12.0pt; line-height: 115%;"></span></div>
</td>
  <td style="padding: .75pt .75pt .75pt .75pt;"><div class="MsoNormal">
<span lang="EN-IN">Read and Write</span><span lang="EN-IN" style="font-size: 12.0pt; line-height: 115%;"></span></div>
</td>
 </tr>
<tr style="mso-yfti-irow: 2;">
  <td style="padding: .75pt .75pt .75pt .75pt;"><div class="MsoNormal">
<span lang="EN-IN">O_RDONLY</span><span lang="EN-IN" style="font-size: 12.0pt; line-height: 115%;"></span></div>
</td>
  <td style="padding: .75pt .75pt .75pt .75pt;"><div class="MsoNormal">
<span lang="EN-IN">Read Only</span><span lang="EN-IN" style="font-size: 12.0pt; line-height: 115%;"></span></div>
</td>
 </tr>
<tr style="mso-yfti-irow: 3;">
  <td style="padding: .75pt .75pt .75pt .75pt;"><div class="MsoNormal">
<span lang="EN-IN">O_WRONLY</span><span lang="EN-IN" style="font-size: 12.0pt; line-height: 115%;"></span></div>
</td>
  <td style="padding: .75pt .75pt .75pt .75pt;"><div class="MsoNormal">
<span lang="EN-IN">Write Only</span><span lang="EN-IN" style="font-size: 12.0pt; line-height: 115%;"></span></div>
</td>
 </tr>
<tr style="mso-yfti-irow: 4;">
  <td style="padding: .75pt .75pt .75pt .75pt;"><div class="MsoNormal">
<span lang="EN-IN">O_CREAT</span><span lang="EN-IN" style="font-size: 12.0pt; line-height: 115%;"></span></div>
</td>
  <td style="padding: .75pt .75pt .75pt .75pt;"><div class="MsoNormal">
<span lang="EN-IN">Create the file</span><span lang="EN-IN" style="font-size: 12.0pt; line-height: 115%;"></span></div>
</td>
 </tr>
<tr style="mso-yfti-irow: 5;">
  <td style="padding: .75pt .75pt .75pt .75pt;"><div class="MsoNormal">
<span lang="EN-IN">O_APPEND</span><span lang="EN-IN" style="font-size: 12.0pt; line-height: 115%;"></span></div>
</td>
  <td style="padding: .75pt .75pt .75pt .75pt;"><div class="MsoNormal">
<span lang="EN-IN">Append the file</span><span lang="EN-IN" style="font-size: 12.0pt; line-height: 115%;"></span></div>
</td>
 </tr>
<tr style="mso-yfti-irow: 6;">
  <td style="padding: .75pt .75pt .75pt .75pt;"><div class="MsoNormal">
<span lang="EN-IN">O_TRUNC</span><span lang="EN-IN" style="font-size: 12.0pt; line-height: 115%;"></span></div>
</td>
  <td style="padding: .75pt .75pt .75pt .75pt;"><div class="MsoNormal">
<span lang="EN-IN">Truncate the file</span><span lang="EN-IN" style="font-size: 12.0pt; line-height: 115%;"></span></div>
</td>
 </tr>
<tr style="mso-yfti-irow: 7;">
  <td style="padding: .75pt .75pt .75pt .75pt;"><div class="MsoNormal">
<span lang="EN-IN">O_EXCL</span><span lang="EN-IN" style="font-size: 12.0pt; line-height: 115%;"></span></div>
</td>
  <td style="padding: .75pt .75pt .75pt .75pt;"><div class="MsoNormal">
<span lang="EN-IN">Stops if file already exists</span><span lang="EN-IN" style="font-size: 12.0pt; line-height: 115%;"></span></div>
</td>
 </tr>
<tr style="mso-yfti-irow: 8; mso-yfti-lastrow: yes;">
  <td style="padding: .75pt .75pt .75pt .75pt;"><div class="MsoNormal">
<span lang="EN-IN">O_NONBLOCK</span><span lang="EN-IN" style="font-size: 12.0pt; line-height: 115%;"></span></div>
</td>
  <td style="padding: .75pt .75pt .75pt .75pt;"><div class="MsoNormal">
<i><span lang="EN-IN">Non-Blocking</span></i><span lang="EN-IN"> usability</span><span lang="EN-IN" style="font-size: 12.0pt; line-height: 115%;"></span></div>
</td>
 </tr>
</tbody></table>
<h2>
<span lang="EN-IN">PERL Code:</span></h2>
<pre><span lang="EN-IN">#!/usr/bin/perl</span></pre>
<pre><span lang="EN-IN"> </span></pre>
<pre><span lang="EN-IN">print "content-type: text/html \n\n"; #The header</span></pre>
<pre><span lang="EN-IN" style="color: red;">use Fcntl;</span><span lang="EN-IN"> #The Module</span></pre>
<pre><span lang="EN-IN"> </span></pre>
<pre><span lang="EN-IN">sysopen (HTML, '/home/html/myhtml.html', <span style="color: red;">O_RDWR|O_EXCL|O_CREAT, 0755</span>);</span></pre>
<pre><span lang="EN-IN">sysopen (HTML, '<span style="color: red;">></span>myhtml.html');</span></pre>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br /></div>
<h1>
<span lang="EN-IN">PERL - File Creation</span></h1>
<span lang="EN-IN">Files are opened and created using the same <i>sysopen</i>
function.</span><br />
<span lang="EN-IN">Our syntax <i>open(FILEHANDLE, '$filename', permissions,
CHMOD);</i> or <i>sysopen(FILEHANDLE, $filename, permissions, CHMOD);</i></span><br />
<span lang="EN-IN">With sysopen you may also set hexidecimal priviledges;
CHMOD values. Sysopen also requires the declaration of a new module for PERL.
We will be using the Fcntl module for now, more on this later. Below we have
created a basic HTML (myhtml.html) file.</span><br />
<h2>
<span lang="EN-IN">PERL Code:</span></h2>
<pre><span lang="EN-IN">#!/usr/bin/perl</span></pre>
<pre><span lang="EN-IN" style="color: red;">use Fcntl;</span><span lang="EN-IN"> #The Module</span></pre>
<pre><span lang="EN-IN"> </span></pre>
<pre><span lang="EN-IN">print "content-type: text/html \n\n"; #The header</span></pre>
<pre><span lang="EN-IN" style="color: red;">sysopen (HTML, 'myhtml.html', O_RDWR|O_EXCL|O_CREAT, 0755);</span></pre>
<pre><span lang="EN-IN">printf HTML "<html>\n"; </span></pre>
<pre><span lang="EN-IN">printf HTML "<head>\n"; </span></pre>
<pre><span lang="EN-IN">printf HTML "<title>My Home Page</title>"; </span></pre>
<pre><span lang="EN-IN">printf HTML "</head>\n"; </span></pre>
<pre><span lang="EN-IN">printf HTML "<body>\n"; </span></pre>
<pre><span lang="EN-IN">printf HTML "<p align='center'>Here we have an HTML </span></pre>
<pre><span lang="EN-IN">page with a paragraph.</p>";</span></pre>
<pre><span lang="EN-IN">printf HTML "</body>\n"; </span></pre>
<pre><span lang="EN-IN">printf HTML "</html>\n"; </span></pre>
<pre><span lang="EN-IN">close (HTML);</span></pre>
<h2>
<span lang="EN-IN">myhtml.html:</span></h2>
<div class="MsoNormal">
<span lang="EN-IN"><html><br />
<head><br />
<title>My Home Page</title></head><br />
<body><br />
<p align='center'>Here we have an HTML page with a paragraph.</p><br />
</body><br />
</html></span></div>
<h2>
<span lang="EN-IN">myhtml.html-browser view:</span></h2>
<div align="center" style="text-align: center;">
<span lang="EN-IN">Here we have an HTML
page with a paragraph.</span></div>
<span lang="EN-IN">Our highlight shows the module we forced PERL to use, and
the sysopen command. FH stands for filehandle, this value can be changed to
whatever the author would like, it is just a way to reference the same file in
a script. We then named the file with read and write priviledges, then told
PERL to check if the file exists, and if not create a new file with 0755 CHMOD
priviledges.</span><br />
<span lang="EN-IN">Below is the shorthand method, the difference here is our
filehandle name has changed, and we are unable to set a CHMOD value with this
function.</span><br />
<h2>
<span lang="EN-IN">PERL Code:</span></h2>
<pre><span lang="EN-IN">open(TEXT,+<newtext.txt.);</span></pre>
<pre><span lang="EN-IN">printf TEXT "Check out our text file!";</span></pre>
<pre><span lang="EN-IN">close (TEXT);</span></pre>
<span lang="EN-IN">We use the <i>printf</i> function instead of print to
actually print our text into the file. Everything inside the printf function is
embeded into our created file.</span><br />
<h1>
<span lang="EN-IN">PERL - Reading from a File</span></h1>
<span lang="EN-IN">It is possible to read lines from files and input them
using the <> <i>input</i> operator. By placing the file handle inside of
the input operator, your script will input that line of the file.</span><br />
<h2>
<span lang="EN-IN">PERL Code:</span></h2>
<pre><span lang="EN-IN">#!/usr/bin/perl</span></pre>
<pre><span lang="EN-IN"> </span></pre>
<pre><span lang="EN-IN">print "content-type: text/html \n\n"; #The header</span></pre>
<pre><span lang="EN-IN">$HTML = "myhtml.html";</span></pre>
<pre><span lang="EN-IN">open (HTML) or die "Can't open the file!";</span></pre>
<pre><span lang="EN-IN">print <HTML>;</span></pre>
<pre><span lang="EN-IN">close (HTML);</span></pre>
<h2>
<span lang="EN-IN">myhtml.pl:</span></h2>
<div align="center" style="text-align: center;">
<span lang="EN-IN">Here we have an HTML
page with a paragraph.</span></div>
<span lang="EN-IN">Here we use a tiny PERL script to display several lines of
HTML code. Each line is stored into an array and automatically printed to the
browser in HTML format using the <> input operator.</span><br />
<h1>
<span lang="EN-IN">PERL - Input Array</span></h1>
<span lang="EN-IN">PERL is able to print out lines of other files with the use
of arrays. Following the example above when we called our HTML file handle
using the input operator, PERL automatically stored each line of the file into
a global array. It is then able to process each element of the array as we
demonstrated in PERL Arrays. This makes it possible to integrate dynamic bits
of HTML code with already existing HTML files.</span><br />
<h2>
<span lang="EN-IN"> </span></h2>
<h2>
<span lang="EN-IN">PERL Code:</span></h2>
<pre><span lang="EN-IN">#!/usr/bin/perl</span></pre>
<pre><span lang="EN-IN"> </span></pre>
<pre><span lang="EN-IN">print "content-type: text/html \n\n"; #The header</span></pre>
<pre><span lang="EN-IN">$HTML = "myhtml.html";</span></pre>
<pre><span lang="EN-IN">open (HTML) or die "Can't open the file!";</span></pre>
<pre><span lang="EN-IN" style="color: red;">@fileinput = <HTML>;</span></pre>
<pre><span lang="EN-IN">print $fileinput[0];</span></pre>
<pre><span lang="EN-IN">print $fileinput[1];</span></pre>
<pre><span lang="EN-IN">print $fileinput[2];</span></pre>
<pre><span lang="EN-IN">print $fileinput[3];</span></pre>
<pre><span lang="EN-IN">print "<table border='1' align='center'><tr></span></pre>
<pre><span lang="EN-IN"><td>Dynamic</td><td>Table</td></tr>";</span></pre>
<pre><span lang="EN-IN">print "<tr><td>Temporarily Inserted</td></span></pre>
<pre><span lang="EN-IN"><td>Using PERL!</td></tr></table>";</span></pre>
<pre><span lang="EN-IN">print $fileinput[4];</span></pre>
<pre><span lang="EN-IN">print $fileinput[5];</span></pre>
<pre><span lang="EN-IN">close (HTML);</span></pre>
<h2>
<span lang="EN-IN">dynamic.pl:</span></h2>
<div align="center">
<table border="1" cellpadding="0" class="MsoNormalTable" style="mso-cellspacing: 1.5pt; mso-yfti-tbllook: 1184;">
 <tbody>
<tr style="mso-yfti-firstrow: yes; mso-yfti-irow: 0;">
  <td style="padding: .75pt .75pt .75pt .75pt;"><div class="MsoNormal">
<span lang="EN-IN">Dynamic</span><span lang="EN-IN" style="font-size: 12.0pt; line-height: 115%;"></span></div>
</td>
  <td style="padding: .75pt .75pt .75pt .75pt;"><div class="MsoNormal">
<span lang="EN-IN">Table</span><span lang="EN-IN" style="font-size: 12.0pt; line-height: 115%;"></span></div>
</td>
 </tr>
<tr style="mso-yfti-irow: 1; mso-yfti-lastrow: yes;">
  <td style="padding: .75pt .75pt .75pt .75pt;"><div class="MsoNormal">
<span lang="EN-IN">Temporarily Inserted</span><span lang="EN-IN" style="font-size: 12.0pt; line-height: 115%;"></span></div>
</td>
  <td style="padding: .75pt .75pt .75pt .75pt;"><div class="MsoNormal">
<span lang="EN-IN">Using PERL!</span><span lang="EN-IN" style="font-size: 12.0pt; line-height: 115%;"></span></div>
</td>
 </tr>
</tbody></table>
</div>
<div align="center" style="text-align: center;">
<span lang="EN-IN">Here we have an HTML
page with a paragraph.</span></div>
<span lang="EN-IN">To permanently change a file, replace the <i>print</i>
function with the <i>printf</i> function.</span><br />
<h1>
<span lang="EN-IN">PERL - Copying Files</span></h1>
<span lang="EN-IN">We can duplicate a file using the <i>copy</i> function.
Copy takes two values the URL of the file to be copied and the URL of the new
file. Since we want to duplicate the file in this example, we won't change the
directory path but instead, just give the file a new name. If we used the same
file name or the same URL, PERL will rewrite over the file if permissions
allow.</span><br />
<span lang="EN-IN">We also must use a new module, the copy module of course.</span><br />
<h2>
<span lang="EN-IN">PERL Code:</span></h2>
<pre><span lang="EN-IN">#!/usr/bin/perl</span></pre>
<pre><span lang="EN-IN" style="color: red;">use File::Copy;</span></pre>
<pre><span lang="EN-IN"> </span></pre>
<pre><span lang="EN-IN">print "content-type: text/html \n\n"; #The header</span></pre>
<pre><span lang="EN-IN">$filetobecopied = "myhtml.html.";</span></pre>
<pre><span lang="EN-IN">$newfile = "myhtml.html.";</span></pre>
<pre><span lang="EN-IN" style="color: red;">copy($filetobecopied, $newfile) or die "File cannot be copied.";</span></pre>
<span lang="EN-IN">Here, we have simply duplicated the "myhtml.html"
file and will be using it in further examples.</span><br />
<span lang="EN-IN">If we wanted to copy the file to a new directory, we can
edit our variables to match the directory we wish to copy the file to.</span><br />
<h2>
<span lang="EN-IN">PERL Code:</span></h2>
<pre><span lang="EN-IN">#!/usr/bin/perl</span></pre>
<pre><span lang="EN-IN" style="color: red;">use File::Copy;</span></pre>
<pre><span lang="EN-IN"> </span></pre>
<pre><span lang="EN-IN">print "content-type: text/html \n\n"; #The header</span></pre>
<pre><span lang="EN-IN" style="color: red;">$filetobecopied = "myhtml.html.";</span></pre>
<pre><span lang="EN-IN" style="color: red;">$newfile = "html/myhtml.html.";</span></pre>
<pre><span lang="EN-IN">copy($filetobecopied, $newfile) or die "File cannot be copied.";</span></pre>
<span lang="EN-IN">Now we have copied the file from its current directory to
an HTML directory.</span><br />
<span lang="EN-IN">When using PERL on the web, it is best to use complete
internet URL. We used a shorthand way in the example but a better solution may
be to hardcode the full URL meaning; http://www.your.com/myhtml.html.</span><br />
<h1>
<span lang="EN-IN">PERL - Moving Files</span></h1>
<span lang="EN-IN">Moving a file requires the use of the <i>move</i> function.
This functions works exactly as the copy function from above and we send PERL
the same module. The difference is that instead of copying we are 'cutting' the
file and sending it to a new location. It works the same as cutting and pasting
text from an office document to another.</span><br />
<h2>
<span lang="EN-IN">PERL Code:</span></h2>
<pre><span lang="EN-IN">#!/usr/bin/perl</span></pre>
<pre><span lang="EN-IN">use File::Copy;</span></pre>
<pre><span lang="EN-IN"> </span></pre>
<pre><span lang="EN-IN">print "content-type: text/html \n\n"; #The header</span></pre>
<pre><span lang="EN-IN">$oldlocation = "myhtml.html";</span></pre>
<pre><span lang="EN-IN">$newlocation = "html/myhtml.html";</span></pre>
<pre><span lang="EN-IN" style="color: red;">move($oldlocation, $newlocation);</span></pre>
<span lang="EN-IN">Now our file has been completly removed from its current
location and placed into the new location.</span><br />
<h1>
<span lang="EN-IN">PERL - Deleting Files</span></h1>
<span lang="EN-IN">Use the <i>unlink</i> function to delete specific files
from your web server. The best solution is often to set a variable name equal
to the URL of the file you wish to delete.</span><br />
<div class="MsoNormal">
<br /></div>
<h2>
<span lang="EN-IN">PERL Code:</span></h2>
<pre><span lang="EN-IN">#!/usr/bin/perl</span></pre>
<pre><span lang="EN-IN"> </span></pre>
<pre><span lang="EN-IN">print "content-type: text/html \n\n";<span style="mso-tab-count: 1;"> </span>#The header</span></pre>
<pre><span lang="EN-IN">$file = "newtext.txt";</span></pre>
<pre><span lang="EN-IN" style="color: red;">if (unlink($file) == 0) {</span></pre>
<pre><span lang="EN-IN"><span style="mso-spacerun: yes;">    </span>print "File deleted successfully.";</span></pre>
<pre><span lang="EN-IN">} else {</span></pre>
<pre><span lang="EN-IN"><span style="mso-spacerun: yes;">    </span>print "File was not deleted.";</span></pre>
<pre><span lang="EN-IN">}</span></pre>
<h2>
<span lang="EN-IN">deletefiles.pl:</span></h2>
<div class="MsoNormal">
<span lang="EN-IN">File deleted successfully. </span></div>
<h1>
<span lang="EN-IN">PERL - Removing Multiple Files at Once</span></h1>
<span lang="EN-IN">Multiple files can be removed at once if we first create an
array of files to be deleted and then loop through each one. There are several
ways to go about this process.</span><br />
<h2>
<span lang="EN-IN">PERL Code:</span></h2>
<pre><span lang="EN-IN">#!/usr/bin/perl</span></pre>
<pre><span lang="EN-IN"> </span></pre>
<pre><span lang="EN-IN">print "content-type: text/html \n\n";<span style="mso-tab-count: 1;"> </span>#The header</span></pre>
<pre><span lang="EN-IN">@files = ("newtext.txt","moretext.txt","yetmoretext.txt");</span></pre>
<pre><span lang="EN-IN">foreach $file (@files) {</span></pre>
<pre><span lang="EN-IN"><span style="mso-spacerun: yes;">    </span>unlink($file);</span></pre>
<pre><span lang="EN-IN">}</span></pre>
<div class="MsoNormal">
<br /></div>
</div>

PERL FILE MANAGEMENT

PERL - File Handling Now we shift gears as we introduce file handling. In PERL files are given a name, a handle, basically another w...

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