(PECL ssh2 >= 0.12)
ssh2_auth_agent — Authenticate over SSH using the ssh agent
$session
   , string $username
   )Authenticate over SSH using the ssh agent
Note: The ssh2_auth_agent() function will only be available when the ssh2 extension is compiled with libssh >= 1.2.3.
sessionAn SSH connection link identifier, obtained from a call to ssh2_connect().
usernameRemote user name.
   Returns TRUE on success or FALSE on failure.
  
Example #1 Authenticating with a ssh agent
<?php
$connection = ssh2_connect('shell.example.com', 22);
if (ssh2_auth_agent($connection, 'username')) {
  echo "Authentication Successful!\n";
} else {
  die('Authentication Failed...');
}
?>