PowerShell

SFTP Upload Large File in Parts

See more SFTP Examples

Demonstrates how to split a large file into N parts and then upload each part separately. This technique can be used to potentially avoid limits a SFTP server might impose on upload file size. PowerShell

Add-Type -Path "C:\chilkat\ChilkatDotNet47-x64\ChilkatDotNet47.dll"

$success = $false

# This example assumes the Chilkat API to have been previously unlocked.
# See Global Unlock Sample for sample code.

$sftp = New-Object Chilkat.SFtp

# Set some timeouts, in milliseconds:
$sftp.ConnectTimeoutMs = 5000
$sftp.IdleTimeoutMs = 10000

# Connect to the SSH server.  
# The standard SSH port = 22
# The hostname may be a hostname or IP address.
$hostname = "sftp.example.com"
$port = 22
$success = $sftp.Connect($hostname,$port)
if ($success -ne $true) {
    $($sftp.LastErrorText)
    exit
}

# Authenticate with the SSH server.  Chilkat SFTP supports
# both password-based authenication as well as public-key
# authentication.  This example uses password authenication.
$success = $sftp.AuthenticatePw("myLogin","myPassword")
if ($success -ne $true) {
    $($sftp.LastErrorText)
    exit
}

# After authenticating, the SFTP subsystem must be initialized:
$success = $sftp.InitializeSftp()
if ($success -ne $true) {
    $($sftp.LastErrorText)
    exit
}

# Open a remote file for writing on the SSH server.
# If the file already exists, it is overwritten.
# (Specify "createNew" instead of "createTruncate" to
# prevent overwriting existing files.)
$handle = $sftp.OpenFile("big.zip","writeOnly","createTruncate")
if ($sftp.LastMethodSuccess -ne $true) {
    $($sftp.LastErrorText)
    exit
}

# We're going to upload the local file "qa_data/zips/big.zip" (a relative local path from our current working directory)
# to the SFTP server.
$localFilePath = "qa_data/zips/big.zip"

# Rather than uploading in one shot, we'll read the local file in chunks
# and upload a chunk at a time.
$fac = New-Object Chilkat.FileAccess

$success = $fac.OpenForRead($localFilePath)
if ($success -eq $false) {
    $sftp.CloseHandle($handle)
    $($fac.LastErrorText)
    exit
}

# If we were to split the local file into 128K chunks, how many chunks (blocks) would
# we have, including the last partial block?
$blockSize = 131072
$numBlocks = $fac.GetNumBlocks($blockSize)
$("Number of blocks = " + $numBlocks)

$bd = New-Object Chilkat.BinData
$i = 0
while ($i -lt $numBlocks) {
    # Read the Nth block, which gets appended to the bd.  (which means
    # we must clear the contents of bd before the next iteration)
    $success = $fac.ReadBlockBd($i,$blockSize,$bd)
    if ($success -eq $false) {
        $sftp.CloseHandle($handle)
        $($fac.LastErrorText)
        exit
    }

    # Upload this block to the open remote file.
    $success = $sftp.WriteFileBd($handle,$bd)
    if ($success -eq $false) {
        $($sftp.LastErrorText)
        exit
    }

    # Clear the contents for the next iteration.
    $bd.Clear()

    $i = $i + 1
}

# Close the local file.
$fac.FileClose()

# -----------------------------------------------------------------------------
# This is important.  You must close the handle on the server.
# Otherwise open handles will accumulate on the server until eventually a limit
# is reached and the server will fail on a call to OpenFile.
# -----------------------------------------------------------------------------

# Close the remote file handle on the server.
$success = $sftp.CloseHandle($handle)
if ($success -ne $true) {
    $($sftp.LastErrorText)
    exit
}

$("Success.")