Copying files with Robocopy

Published on: 25th Nov 2019

Updated on: 16th Jan 2022

Explanation

Copying files using the Copy-Item command can be slow. The fastest copying utility on Windows is Robocopy. The following script copies all files in D:\temp3\test to two destinations listed in dst-dir.csv file.

Here is the script for copy-file-to-dir.ps1

## sample values
#
#$src = 'D:\temp3\test'
#$dst_csv = "$PSScriptRoot\dst-dir.csv"
#

param (
    [string]$src = $(Read-Host("Source directory")),
    [string]$dst_csv = $(Read-Host("Destination CSV file name (blank for default)"))
)

if ($src.Length -eq 0) {
    Write-Host "==> the source directory has not been specified. Exit."
    return
}

if (!(Test-Path $src)) {
    Write-Host "==> the source directory does not exist. Exit."
    return
}

if ($dst_csv.Length -eq 0) {
    #set default dir
    $dst_csv = "$PSScriptRoot\dst-dir.csv"
}

if (!(Test-Path $dst_csv)) {
    $dst_csv2 = "$PSScriptRoot\$dst_csv"

    # test to see if the user passes in the filename without a path
    if (!(Test-Path $dst_csv2)) {
        Write-Host "==> the CSV file does not exist. Exit."
        return
    }
    else {
        # the user pass in the filename without path
        $dst_csv = $dst_csv2
    }
}

#====================================

$dst = Import-Csv -Path $dst_csv
$item_cnt = $dst.Length

#====================================

Write-Host "=> cloning source = $src"
Write-Host "=> destination csv file $dst_csv (found $item_cnt destinations)"
Write-Host

$ans = Read-Host("Proceed with the copy process [y/n]?")

if ($ans -eq "n") {
    Write-Host "==> the process has been cancelled"
    return
}

Write-Host

Foreach ($item in $dst) {
    $d = $item.dst_dir        
    Write-Host -NoNewline "==> copying to $d"
    
    $cmd = "robocopy $src $d /S /E /DCOPY:T /R:10 /W:10 /NP /TEE"
    Invoke-Expression -Command $cmd | Out-Null

    Write-Host "=> OK"    
}

The contents of the "dst-dir.csv" file where it has 3 lines. The first line is the header line and the next 2 lines are the directory to be copied.

dst_dir
D:\temp3\apps\app1\js
D:\temp3\apps\app2\js

Notes

• Read-Host("Source directory") - prompts the message on the screen and waits for user input.
• [string]$src = $(Read-Host("Source directory")) - the $(..) means read the result from Read-Host and then assign it to the $src parameter.
• Test-Path $dst_csv - returns true if the $dst_csv file exists. Test-Path works for file systems and other systems such as IIS:\ drive (imported from WebAdministration module). So, it depends on the context that you are running.
• Import-Csv -Path $dst_csv - import the file using CSV format.
• Write-Host -NoNewline ".." - show the message on the screen without ending with a line feed. As a result, the next Write-Host will continue writing the message from the cursor position.
• Invoke-Expression -Command $cmd - executes the DOS command.
• | Out-Null - the pipe symbol | means continue processing the previous result and Out-Null means hide the result or output.

Use case

• To speed up the backup of files. Robocopy is fast in synchronizing files between the source and destination directory by sending the delta (i.e., the changes). This works best if you are synchronizing the files between two servers (except for the first time synchronizing).

• You may use any other external program to synchronize the files. What you need is to replace the robocopy command with the external program command.

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Author

Lau Hon Wan, software developer.