Shell like program - Perl Code Bank

                #!/usr/bin/perl
#Created by TheSilentDrifter 02/25/2009 | 6:47 MST#
use strict;

my($user, $pass, $input);

sub help 
{
	print "cd | cat | ls\/dir | mkdir | quit | touch | chmod | rm | edit\n"; 
}

sub cat 
{
	my($file_o, @o_file);
		print "cat: What file would you like to open?: ";
	chomp($file_o = <STDIN>);
	if(-e $file_o) 
	{
		open FILE, "<$file_o" or warn "cat: Error opening file!: $!\n";
		@o_file = <FILE>;
		foreach (@o_file) 
		{
			print "$_\n";
		}
	} 
	else 
	{ 
		print "cat: Could not open file because: $!\n";
	}
}

sub mk_dir 
{
	my($new_dir, $input);
		print "mkdir: What would you like to call the new folder?: ";
	chmod($new_dir = <STDIN>);
	if(-e $new_dir) 
	{
			print "mkdir: Warning! This folder exists! Would you like to overwrite it?: [YES/no]";
		chomp($input = <STDIN>);
		if($input eq "" || ($input =~ m/\byes\b/i || m/\by\b/i)) 
		{
			mkdir $new_dir, 0755 or warn "mkdir: Could not make $new_dir: $!\n";
		} 
		else 
		{
		print "mkdir: Ok, the directory will not be created.\n";
		}
	}
	else 
	{
		mkdir $new_dir, 0755 or warn "Could not make $new_dir: $!\n";
	}
}

sub touch 
{
	my($file, $input);
		print "touch: Insert the name of the file you wish to create: ";
	chomp($file = <STDIN>);
	if(-e $file) 
	{
			print "touch: " . $file . " exists. Would you like to overwrite it?: [YES/no]";
		chomp($input = <STDIN>);
		if(($input =~ m/\byes\b/i || $input=~ m/\by\b/i) || $input eq "") 
		{
			open(FILE, ">$file") or warn "touch: Could not create file: $!\n";
		} 
		else 
		{
			print "touch: File will not be created.\n";
		}
	} 
	else 
	{
		open(FILE, ">$file") or warn "touch: Could not create file: $!\n";
	}
}

sub dir 
{
	my($dir, $num, @dir);
	sub n 
	{
		$num += 1;
	}
	@dir = glob "*";
		print "\nFiles in current directory: \n\n";
	foreach $dir (@dir) 
	{
		print "\t(" . &n . ") " . $dir . "\n\n";
	}
}

sub ch_mod 
{
	my($file, $file_perm);
		print "chmod: What file should have permissions changed on it?: ";
	chomp($file = <STDIN>);
		print "chmod: What permissions should " . $file . " have?: ";
	chomp($file_perm = <STDIN>);
	oct($file_perm);
	if ($file_perm eq "0644" or $file_perm eq "644") 
	{
		chmod(0644, $file) or warn "chmod: " . $file . "'s permissions were not changed!: $!\n";
	} 
	elsif ($file_perm eq "0755" or $file_perm eq "755") 
	{
		chmod(0755, $file) or warn "chmod: " . $file . "'s permissions were not changed!: $!\n";
	} 
	elsif ($file_perm eq "0777" or $file_perm eq "777") 
	{
		chmod(0777, $file) or warn "chmod: " . $file . "'s permissions were not changed!: $!\n";
	} 
	else 
	{
		warn "chmod: " . $file . "'s permissions were not changed because you did not enter a permission level!\n";
	}
}

sub cd 
{
	my($dir, $input);
		print "cd: Where would you like to go?: ";
	chomp($input = <STDIN>);
	chdir $dir or warn "cd: Cannot change to directory: $!\n";
}

sub rm 
{
	my($file);		
		print "rm: What file would you like to remove?: ";
	chomp($file = <STDIN>);
	if (-e $file) 
	{
			print "rm: Are you sure you want to delete the file?: [YES/no]";
		chomp($input = <STDIN>);
		if ($input eq "" || ($input =~ /\byes\b/i || $input =~ /\by\b/i))
		{
			unlink $file or warn "rm: " . $file . " could not be removed: $!\n";
				print "rm: " . $file . " was removed.\n";
		} 
		else 
		{
			print "rm: The file will not be removed then.\n";
		} 
	}	
	else 
	{
		warn "rm: " . $file . "Could not be removed!: $!\n";
	}
}

sub edit 
{
	my($old_file, $new_file);
		print "edit: What file would you like to edit?: ";
	chomp($old_file = <STDIN>);
	if (-e $old_file) 
	{
		my($orig_word, $new_word, @edit, $line);
			print "edit: What word in \"" . $old_file . "\" would you like to edit?: ";
		chomp($orig_word = <STDIN>);
			print "edit: What would you like to replace \"" . $orig_word . "\" with in \"" . $old_file . "\"?: ";
		chomp($new_word = <STDIN>);
		open(OLD, "<$old_file") || warn "edit: Could not open file: $!\n";
		$new_file = "$old_file~";
		open(NEW, ">>$new_file") || warn "edit: Could not open file: $!\n";
		while(<OLD>) 
		{
			$line = s/\b$orig_word\b/$new_word/ig;
			if($line) 
			{
					print NEW "$_";
					print "edit: \"" . $orig_word . "\" was replaced with \"" . $new_word . "\".\n";
				close(OLD);
				close(NEW);
				rename $new_file, $old_file || die "edit: Error replacing original file: $!\n";
			}
			else
			{
				print "edit: Could not replace \"" . $orig_word . "\": $!\n";
				close(OLD);
				close(NEW);
			}
						
		}
	}
	
}

sub re_name 
{
	my($old_name, $new_name);
		print "rename: What file would you like to rename?: ";
	chomp($old_name = <STDIN>);	
	if (-e $old_name)
	{
			print "rename: What should \"" . $old_name . "\" be changed to?: ";
		chomp($new_name = <STDIN>);
		if( -e $new_name) 
		{
			warn "rename: Cannot rename to \"" . $new_name . "\": It already exists!\n";
		}
		else
		{
			rename $old_name, $new_name || warn "rename: Could not rename \"" . $old_name . "\": $!\n";
			print "rename: \"" . $old_name . "\" is now named \"" . $new_name . "\". \n";
		}
	}
	else 
	{
		warn "rename: Could not rename file: $!\n";
	}
}

do 
{
		print "Users\@Shell> ";
	chomp($input = <STDIN>);	
	SWITCH: 
	{
		if($input eq "help") {help(); last SWITCH;}
		if($input eq "cat") {cat(); last SWITCH;}
		if($input eq "cd") {cd(); last SWITCH;}
		if($input eq "mkdir") {mk_dir(); last SWITCH;}
		if($input eq "touch") {touch(); last SWITCH;}
		if($input eq "chmod") {ch_mod(); last SWITCH;}
		if($input eq "rm" ) {rm(); last SWITCH;}
		if($input eq "edit") {edit(); last SWITCH;}
		if($input eq "rename") {re_name(); last SWITCH;}
		if($input eq "ls" || $input eq "dir") {dir(); last SWITCH;}	
	}
} 
until (($input =~ /quit/i) || ($input =~ /exit/i));