Answer:

To upgrade a single package, you just need to install the package again, e.g.

# sudo apt-get install nginx

Answer:

To print a string of "Hello World" to the standard output in different scripting languages

1. Perl

print "Hello, World!";

2. Python

print('Hello, World!')

3. PHP

echo "Hello, World!";

4. Ruby

puts "Hello, World!"

Answer:

In PHP, to remove object (e.g. with the key = foo in the following example) from array inside foreach loop, you can try:

<?php

foreach($array as $key=> $value) {
    if ($key == "foo") {
        unset($array[$key]);
    }
}

Answer:

If you are using PHP 5.2 or above (in fact, at the moment of writing, you should use at least PHP 5.3+), you can use the following easy method:

if(filter_var($ip, FILTER_VALIDATE_IP)) 
{
  // Valid IP
}
else 
{
  // Invalid IP
}

Answer:

To get the current PHP include path's setting, you can use the function get_include_path

E.g.

echo get_include_path();

Usually it is used with the set_include_path for adding extra path to the existing include_path,

E.g.

set_include_path(get_include_path() . PATH_SEPARATOR . "/data/path");

Answer:

To check the amount of memory used by PHP process, use the function - memory_get_usage

E.g.

// Returns the amount of memory, in bytes, that's currently being allocated to your PHP script.
echo memory_get_usage(); 

Answer:

magic_quotes_gpc is a legacy PHP function that no longer be supported in PHP 6.0. So you should disable them to make sure your application not break in the future version of PHP.

To disable it, edit the php.ini

vi /etc/php.ini

Locate and set

magic_quotes_gpc = off;

Remember to restart web server such as Apache if needed.

Answer:

To validate an email address using PHP, you can use the code below. (It is from www.ilovejackdaniels.com/php/email-address-validation , it is not perfect, but better than most of the average solutions found in the Internet)

<?php

function check_email_address($email) {
  // First, we check that there's one @ symbol, 
  // and that the lengths are right.
  if (!ereg("^[^@]{1,64}@[^@]{1,255}$", $email)) {
    // Email invalid because wrong number of characters 
    // in one section or wrong number of @ symbols.
    return false;
  }
  // Split it into sections to make life easier
  $email_array = explode("@", $email);
  $local_array = explode(".", $email_array[0]);
  for ($i = 0; $i < sizeof($local_array); $i++) {
    if
(!ereg("^(([A-Za-z0-9!#$%&'*+/=?^_`{|}~-][A-Za-z0-9!#$%&
↪'*+/=?^_`{|}~\.-]{0,63})|(\"[^(\\|\")]{0,62}\"))$",
$local_array[$i])) {
      return false;
    }
  }
  // Check if domain is IP. If not, 
  // it should be valid domain name
  if (!ereg("^\[?[0-9\.]+\]?$", $email_array[1])) {
    $domain_array = explode(".", $email_array[1]);
    if (sizeof($domain_array) < 2) {
        return false; // Not enough parts to domain
    }
    for ($i = 0; $i < sizeof($domain_array); $i++) {
      if
(!ereg("^(([A-Za-z0-9][A-Za-z0-9-]{0,61}[A-Za-z0-9])|
↪([A-Za-z0-9]+))$",
$domain_array[$i])) {
        return false;
      }
    }
  }
  return true;
}

Answer:

It is easy to generate a CSV file using the fputcsv function. One of a very common problems is even the file is UTF-8 encoded, Microsoft Excel is still unable to identiy the file as UTF-8.

To solve this, you need to add the UTF-8 BOM to the beginning of the file.

E.g.

<?php 

echo "\xEF\xBB\xBF" . $csvdata; // Assume $csvdata contains the CSV string you want to output

Answer:

The error control operator (the @) is useful to ignore any error messages that might be generated by PHP.

E.g.

<?php

$my_value = @$my_array[$key];

The above statement will not generate any warning even if the index $key doesn't exist.