PHP ActiveX

Create a Hard Link on an SFTP Server

Demonstrates the Chilkat SFtp.HardLink method, which creates a hard link to an existing remote file. The first argument is the existing file and the second is the new link path. It uses the OpenSSH hardlink@openssh.com extension and succeeds only when the server supports it.

Background: A hard link is a second name for the same file data, not a pointer to a path: both names are equal, the data persists until the last name is removed, and there is no "original" to break. Unlike a symbolic link it cannot span filesystems and cannot target a directory. Because it depends on a non-standard OpenSSH extension, expect it to fail against servers that do not implement it.

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<?php

$success = 0;

//  Demonstrates the SFtp.HardLink method, which creates a hard link to an existing remote file.
//  The 1st argument is the existing file and the 2nd is the new link path.

$sftp = new COM("Chilkat.SFtp");

//  Connect, authenticate, and initialize the SFTP subsystem.
$port = 22;
$success = $sftp->Connect('sftp.example.com',$port);
if ($success == 0) {
    print $sftp->LastErrorText . "\n";
    exit;
}

//  Normally you would not hard-code the password in source.  You should instead obtain it
//  from an interactive prompt, environment variable, or a secrets vault.
$password = 'mySshPassword';

$success = $sftp->AuthenticatePw('mySshLogin',$password);
if ($success == 0) {
    print $sftp->LastErrorText . "\n";
    exit;
}

$success = $sftp->InitializeSftp();
if ($success == 0) {
    print $sftp->LastErrorText . "\n";
    exit;
}

//  Create a hard link.  This uses the OpenSSH hardlink@openssh.com extension and succeeds only
//  when the server supports it.
$success = $sftp->HardLink('subdir/data.bin','subdir/data_backup.bin');
if ($success == 0) {
    print $sftp->LastErrorText . "\n";
    exit;
}

print 'Hard link created.' . "\n";

$sftp->Disconnect();

?>