PowerShell FTP download files and subfolders
The .NET framework or PowerShell do not have any explicit support for recursive file operations (including downloads). You have to implement the recursion yourself:
- List the remote directory
- Iterate the entries, downloading files and recursing into subdirectories (listing them again, etc.)
Tricky part is to identify files from subdirectories. There's no way to do that in a portable way with the .NET framework (FtpWebRequest
or WebClient
). The .NET framework unfortunately does not support the MLSD
command, which is the only portable way to retrieve directory listing with file attributes in FTP protocol. See also Checking if object on FTP server is file or directory.
Your options are:
- Do an operation on a file name that is certain to fail for file and succeeds for directories (or vice versa). I.e. you can try to download the "name". If that succeeds, it's a file, if that fails, it a directory.
- You may be lucky and in your specific case, you can tell a file from a directory by a file name (i.e. all your files have an extension, while subdirectories do not)
- You use a long directory listing (
LIST
command =ListDirectoryDetails
method) and try to parse a server-specific listing. Many FTP servers use *nix-style listing, where you identify a directory by thed
at the very beginning of the entry. But many servers use a different format. The following example uses this approach (assuming the *nix format)
function DownloadFtpDirectory($url, $credentials, $localPath)
{
$listRequest = [Net.WebRequest]::Create($url)
$listRequest.Method = [System.Net.WebRequestMethods+Ftp]::ListDirectoryDetails
$listRequest.Credentials = $credentials
$lines = New-Object System.Collections.ArrayList
$listResponse = $listRequest.GetResponse()
$listStream = $listResponse.GetResponseStream()
$listReader = New-Object System.IO.StreamReader($listStream)
while (!$listReader.EndOfStream)
{
$line = $listReader.ReadLine()
$lines.Add($line) | Out-Null
}
$listReader.Dispose()
$listStream.Dispose()
$listResponse.Dispose()
foreach ($line in $lines)
{
$tokens = $line.Split(" ", 9, [StringSplitOptions]::RemoveEmptyEntries)
$name = $tokens[8]
$permissions = $tokens[0]
$localFilePath = Join-Path $localPath $name
$fileUrl = ($url + $name)
if ($permissions[0] -eq 'd')
{
if (!(Test-Path $localFilePath -PathType container))
{
Write-Host "Creating directory $localFilePath"
New-Item $localFilePath -Type directory | Out-Null
}
DownloadFtpDirectory ($fileUrl + "/") $credentials $localFilePath
}
else
{
Write-Host "Downloading $fileUrl to $localFilePath"
$downloadRequest = [Net.WebRequest]::Create($fileUrl)
$downloadRequest.Method = [System.Net.WebRequestMethods+Ftp]::DownloadFile
$downloadRequest.Credentials = $credentials
$downloadResponse = $downloadRequest.GetResponse()
$sourceStream = $downloadResponse.GetResponseStream()
$targetStream = [System.IO.File]::Create($localFilePath)
$buffer = New-Object byte[] 10240
while (($read = $sourceStream.Read($buffer, 0, $buffer.Length)) -gt 0)
{
$targetStream.Write($buffer, 0, $read);
}
$targetStream.Dispose()
$sourceStream.Dispose()
$downloadResponse.Dispose()
}
}
}
Use the function like:
$credentials = New-Object System.Net.NetworkCredential("user", "mypassword")
$url = "ftp://ftp.example.com/directory/to/download/"
DownloadFtpDirectory $url $credentials "C:\target\directory"
The code is translated from my C# example in C# Download all files and subdirectories through FTP.
Though Microsoft does not recommend FtpWebRequest
for a new development.
If you want to avoid troubles with parsing the server-specific directory listing formats, use a 3rd party library that supports the MLSD
command and/or parsing various LIST
listing formats; and recursive downloads.
For example with WinSCP .NET assembly you can download whole directory with a single call to Session.GetFiles
:
# Load WinSCP .NET assembly
Add-Type -Path "WinSCPnet.dll"
# Setup session options
$sessionOptions = New-Object WinSCP.SessionOptions -Property @{
Protocol = [WinSCP.Protocol]::Ftp
HostName = "ftp.example.com"
UserName = "user"
Password = "mypassword"
}
$session = New-Object WinSCP.Session
try
{
# Connect
$session.Open($sessionOptions)
# Download files
$session.GetFiles("/directory/to/download/*", "C:\target\directory\*").Check()
}
finally
{
# Disconnect, clean up
$session.Dispose()
}
Internally, WinSCP uses the MLSD
command, if supported by the server. If not, it uses the LIST
command and supports dozens of different listing formats.
The Session.GetFiles
method is recursive by default.
(I'm the author of WinSCP)
For retrieving files /folder from FTP via powerShell I wrote some functions, you can get even hidden stuff from FTP.
Example for getting all files and subfolders (even hidden ones) in a specific folder:
Get-FtpChildItem -ftpFolderPath "ftp://myHost.com/root/leaf/" -userName "User" -password "pw" -Directory -File
You can just copy the functions from the following module without needing any 3rd library installed: https://github.com/AstralisSomnium/PowerShell-No-Library-Just-Functions/blob/master/FTPModule.ps1