PHP CLI в командной строке(command line)

fopen("php://stdin", "r")

mail_errors.php

<?php
// tail -f /var/log/mail.log | php /etc/postfix/myscripts/mail_errors.php
 
while (false !== ($line = fgets(STDIN))) {
    if
    (preg_match("/reject|warning|error|fatal|panic|Permerror/i", $line)) {
        echo $line;
    }
}

php -r 'print_r(get_defined_constants());'

<?php
 
// show them a message to enter their name
echo "Tell us your name: " . PHP_EOL;
 
// the script will wait here until the user has entered something and hit ENTER
$name = read_stdin();
 
// This will display the thank you message including their name they entered.
echo "Thank you $name. Welcome to my site" . PHP_EOL;
 
// our function to read from the command line
function read_stdin()
{
        $fr=fopen("php://stdin","r");   // open our file pointer to read from stdin
        $input = fgets($fr,128);        // read a maximum of 128 characters
        $input = rtrim($input);         // trim any trailing spaces.
        fclose ($fr);                   // close the file handle
        return $input;                  // return the text entered
}
?>