I was using command-line PHP to create an interactive script and wanted the user to enter just one character of input - in response a Yes/No question.  Had some trouble finding a way to do so using fgets(), fgetc(), various suggestions using readline(), popen(), etc.  Came up with the following that works quite nicely:

$ans = strtolower( trim( `bash -c "read -n 1 -t 10 ANS ; echo \\\$ANS"` ) );

The best and simplest way to get input from a user in the CLI with only PHP is to use fgetc() function with the STDIN constant:

<?php

echo 'Are you sure you want to quit? (y/n) ';
$input = fgetc(STDIN);

if ($input == 'y')
{
    exit(0);
}

?>

To read a single key-press in CLI mode, you can either use ncurses (which will probably require additional modules for PHP) or get nasty with the *nix "/bin/stty" command)

<?php
   function stty($options) {
      exec($cmd = "/bin/stty $options", $output, $el);
      $el AND die("exec($cmd) failed");
      return implode(" ", $output);
   }

   function getchar($echo = false) {
      $echo = $echo ? "" : "-echo";

      # Get original settings
      $stty_settings = preg_replace("#.*; ?#s", "", stty("--all"));

      # Set new ones
      stty("cbreak $echo");

      # Get characters until a PERIOD is typed,  
      # showing their hexidecimal ordinal values.
      printf("> ");
      do {
         printf("%02x ", ord($c = fgetc(STDIN)));
      } while ($c != '.');

      # Return settings
      stty($stty_settings);
   }

   getchar();
?>

You can't just simple print separated characters of a text which is encoded in multibyte character set like this;
Because fgetc() will break each multibyte character on its every byte. Consider this example: 

<?php
$path = 'foo/cyrillic.txt';
$handle = fopen($path, 'rb');
while (FALSE !== ($ch = fgetc($handle))) {
    $curs = ftell($hanlde);
    print "[$curs:] $ch\n";
}
/* The result will be something like this:
<
[1]: <
[2]: h
[3]: 2
[4]: >
[5]: �
[6]: �
[7]: �
[8]: �
[9]: �
[10]: �
[11]:  
[12]: �
[13]: �
[14]: �
[15]: �
[16]: �
*/ ?>

I don't think this is the best, but it can be a workaround:
<?php
$path = 'path/to/your/file.ext';

if (!$handle = fopen($path, 'rb')) {
    echo "Can't open ($path) file';
    exit;
}

$mbch = '';    // keeps the first byte of 2-byte cyrillic letters
while (FALSE !== ($ch = fgetc($handle))) {        
    //check for the sign of 2-byte cyrillic letters    
    if (empty($mbch) && (FALSE !== array_search(ord($ch), Array(208,209,129)))) {
        $mbch = $ch;    // keep the first byte
        continue;
    }
    $curs = ftell($handle);
    print "[$curs]: " . $mbch . $ch . PHP_EOL;
    // or print "[$curs]: $mbch$ch\n";
    if (!empty($mbch)) $mbch = '';    // erase the byte after using
}
?>

If you call fgetc(HANDLE) multiple times you must clear buffer before, thus get all unwanted chars to the new new line character.

while (true) {

    //clear buffer - read all unwanted characters
    while(fgetc(STDIN) != "\n");
    
    //get first character from STDIN
    $first = fgetc(STDIN);
}