Tcl

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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Tcl


load ./chilkat.dll

set 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.

set sftp [new_CkSFtp]

#  Connect, authenticate, and initialize the SFTP subsystem.
set port 22
set success [CkSFtp_Connect $sftp "sftp.example.com" $port]
if {$success == 0} then {
    puts [CkSFtp_lastErrorText $sftp]
    delete_CkSFtp $sftp
    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.
set password "mySshPassword"

set success [CkSFtp_AuthenticatePw $sftp "mySshLogin" $password]
if {$success == 0} then {
    puts [CkSFtp_lastErrorText $sftp]
    delete_CkSFtp $sftp
    exit
}

set success [CkSFtp_InitializeSftp $sftp]
if {$success == 0} then {
    puts [CkSFtp_lastErrorText $sftp]
    delete_CkSFtp $sftp
    exit
}

#  Create a hard link.  This uses the OpenSSH hardlink@openssh.com extension and succeeds only
#  when the server supports it.
set success [CkSFtp_HardLink $sftp "subdir/data.bin" "subdir/data_backup.bin"]
if {$success == 0} then {
    puts [CkSFtp_lastErrorText $sftp]
    delete_CkSFtp $sftp
    exit
}

puts "Hard link created."

CkSFtp_Disconnect $sftp

delete_CkSFtp $sftp