repetition operator in perl

Another very handy operator is the repetition operator. Let's say you want to underline some output. You might be tempted to code it like this:
    $underline = '--------------------';
    print $underline;
But Perl lets you define a single character and then how many times you want to repeat it:
    $underline = '-' x 20;
    print $underline; # displays '--------------------'

Dealing with files/directories in Perl

Operator     Function                          
-e       Tests if OPERAND exists.          
-f       Tests if OPERAND is a regular file as opposed to a directory,symbolic link or other type of file
-l       Tests if OPERAND is a symbolic link
-s       Returns size of OPERAND in bytes  
-d       Tests if OPERAND is a directory.  
-T       Tests if OPERAND is a text file.  
 
Example:
#!/usr/bin/perl
if(-e "/tmp/test.pl")
 {
     print "File/directory exists.";
 }
 if(-f "/tmp/test.pl")
 {
     print "File exists";
 }
 $size = -s "/tmp/test.pl";
 print "Size of /tmp/test.pl is $size bytes";

Create an Array of Specific Numbers in Perl

@ft=(1 .. 14);
foreach $h(@ft) {
print "$h ";
}
Which Prints:
1 2 3 4 5 6 7 8 9 10 11 12 13 14
-We created an array and named it ft because we don't like long names.
-We stored 1 through 14 in ft The two periods basically say "through".
-We used Perl's built-in foreach loop to loop over the array and print.
Free Copy and Paste Perl Code:
#!/usr/bin/perl
print "Content-type:text/html\n\n";
@ft=(1 .. 14);
foreach $h(@ft) {
print "$h ";
}
exit;

Making a Directory Using mkdir in Perl

mkdir("hohofiles", 0777) || print $!;
This will make a directory named hohofiles in the current directory.
-We called Perl's built-in mkdir function.
-We enclosed the name we'd like our directory to have in quotation marks. This could have also included the path to our new directory.
-We set permissions to 0777. (Most likely your directory will have permissions of 755 due to a umask of 22.)
-We included two vertical bars or pipes, which mean "or".
-We said to print any error we might receive. The errors are contained in the built-in variable $!
-Summary: make our directory or print errors.
Copy and Paste Perl Code:
#!/usr/bin/perl
print "Content-type:text/html\n\n";
mkdir("hohofiles", 0777) || print $!;
mkdir("hohofiles/jiji", 0777) || print $!;
print " -Done";
exit;

Delete a File Using unlink in Perl

unlink("hohofiles/koko.html");
-We called Perl's built-in unlink function.
-We enclosed the path to the file we want deleted in quotation marks.
Copy and Paste Perl Code:
#!/usr/bin/perl
print "Content-type:text/html\n\n";
unlink("hohofiles/koko.html") || print $!;
print " -Done";
exit;

Use chmod in Perl

chmod(0777, "hohofiles") || print $!;
This will change the permissions of our directory hohofiles to 777.
-We called Perl's built-in chmod function.
-We set permissions to 777.
-We enclosed the name of the thing to be chmoded in quotation marks. This could have also included the path to hohofiles if it was in a different directory than our script.
-We included two vertical bars or pipes, which mean "or".
-We said to print any error we might receive. The errors are contained in the built-in variable $!
-Summary: chmod our directory or print errors.
Copy and Paste Perl Code:
#!/usr/bin/perl
print "Content-type:text/html\n\n";
chmod(0777, "hohofiles") || print $!;
print " -Done";
exit;