if ( system("ls -l | grep datafile.json") == 0 ) {

##</code><code>##

if (-f "datafile.json") {

##</code><code>##

#!/opt/lampp/bin/perl

use strict;

use CGI;
use CGI::Carp 'fatalsToBrowser';
use File::Slurp qw< read_file write_file >;
use JSON qw< from_json to_json >;

use constant USER_ACCOUNT_FILE => '/opt/lampp/htdocs/datafile.json';

sub store_user_account
{
	my ($name, $mail, $pass) = @_;

	my $existing_data = -f USER_ACCOUNT_FILE
		? from_json(scalar read_file(USER_ACCOUNT_FILE, err_mode => 'croak'))
		: [];
	
	push @$existing_data, {
		name  => $name,
		mail  => $mail,
		pass  => $pass,
	};
	
	write_file(
		USER_ACCOUNT_FILE,
		{ atomic => 1, err_mode => 'croak' },
		to_json($existing_data),
	);
}

sub process_cgi
{
	my ($q) = @_;
	
	store_user_account(
		map { scalar $q->param($_) } qw(name mail pass),
	);
	
	print $q->header('text/html');
	print "<p>Finished file.</p>\n";
}

process_cgi( CGI->new );