I had to write this program
because rmdir was claiming not to have enough authorization

context Today I wanted to delete directory…

use strict;
use warnings;
use File::Path qw(remove_tree);

# Specify the directory to be deleted
my $directory = 'c:\\Users\\mydirectory\\mysubdirectory\\';

# Remove the directory
remove_tree($directory, {error => \my $err});

# Check for errors
if (@$err) {
    foreach my $diag (@$err) {
        my ($file, $message) = %$diag;
        if ($file eq '') {
            print "General error: $message\n";
        } else {
            print "Problem unlinking $file: $message\n";
        }
    }
} else {
    print "Directory successfully deleted.\n";
}

#!/usr/bin/perl
# calculator
#
use strict;
use warnings;

sub get_input {
    print "Enter number 1: ";
    chomp(my $num1 = <STDIN>);

    print "Enter number 2: ";
    chomp(my $num2 = <STDIN>);

    print "Enter operator (+, -, *, /): ";
    chomp(my $operator = <STDIN>);

    return ($num1, $num2, $operator);
}

sub calculate {
    my ($num1, $num2, $operator) = '@'_;

    my $result;
    if ($operator eq '+') {
        $result = $num1 + $num2;
    } elsif ($operator eq '-') {
        $result = $num1 - $num2;
    } elsif ($operator eq '*') {
        $result = $num1 * $num2;
    } elsif ($operator eq '/') {
        if ($num2 == 0) {
            die "Error: Division by zero\n";
        }
        $result = $num1 / $num2;
    } else {
        die "Invalid operator\n";
    }

    return $result;
}

# Get input from the user
my ($num1, $num2, $operator) = get_input();

# Calculate the result
my $result = calculate($num1, $num2, $operator);

# Print the result
print "$num1 $operator $num2 = $result\n";

originally posted at https://stacker.news/items/816121

Perl is a high-level, general-purpose programming language that excels in text processing, system administration, web development, and more. Its flexibility and strong regular expression capabilities make it a popular choice for scripting tasks. This article introduces the basics of Perl programming, including an example script.

Basics of Perl

Running a Perl Script

To execute a Perl script, save the code in a file with a .pl extension (e.g., script.pl) and run it from the command line:

perl script.pl

Syntax Highlights

1. Shebang Line: Specify the interpreter.

   #!/usr/bin/perl
   

2. Comments: Use # for single-line comments.

   # This is a comment
   

3. Printing Output:

   print "Hello, World!\n";
   

Variables

Perl has three main variable types:

• Scalars: Single values (numbers, strings, etc.), prefixed by $.

  my $name = "Eva";
  my $age = 35;
  

• Arrays: Ordered lists, prefixed by @.

  my @colors = ("red", "green", "blue");
  

• Hashes: Key-value pairs, prefixed by %.

  my %capitals = ("France" => "Paris", "Japan" => "Tokyo");
  

Control Structures

• Conditional Statements:

  if ($age > 18) {
      print "You are an adult.\n";
  } else {
      print "You are a minor.\n";
  }
  

• Loops:

  for my $color (@colors) {
      print "$color\n";
  }
  

Example Script: Text File Analysis

This script reads a text file, counts the lines, words, and characters, and prints the results.

Script

#!/usr/bin/perl
use strict;
use warnings;

# Check for file argument
if (@ARGV != 1) {
    die "Usage: $0 <filename>\n";
}

my $filename = $ARGV[0];

# Open the file
open(my $fh, '<', $filename) or die "Could not open file '$filename': $!\n";

# Initialize counters
my ($line_count, $word_count, $char_count) = (0, 0, 0);

# Process the file
while (my $line = <$fh>) {
    $line_count++;
    $char_count += length($line);
    $word_count += scalar(split(/\s+/, $line));
}

close($fh);

# Print results
print "File: $filename\n";
print "Lines: $line_count\n";
print "Words: $word_count\n";
print "Characters: $char_count\n";

Explanation

1. Input Validation: Ensures the script is called with a filename.
2. File Handling: Uses open and close for file operations.
3. Counters: Tracks lines, words, and characters.
4. Loop: Reads the file line by line, processing each line.

Running the Script

Save the script as file_analysis.pl and run it with a text file:

perl file_analysis.pl sample.txt

Conclusion

Perl is a powerful tool for scripting and data processing. Its concise syntax and robust text-handling capabilities make it an excellent choice for many tasks. This example demonstrates basic Perl features and encourages further exploration of its vast capabilities.