Here’s a function I wrote to create a large dummy file either filled with zero’s or random characters. The -Target parameter must be eitehr a file including the path or just the path. If the path does not exist, it will be created. If only a path is provided a file with a random file name is generated.
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Function New-BigFile { <# .Synopsis Creates a large dummy file with or without random conntent .DESCRIPTION Creates a large dummy file with or without random conntent Credits for the randome content creation logic goes to Robert Robelo .PARAMETER Target The full path to a folder or file. If the target is a folder a random file name is generated .PARAMETER MegaByte The size of the random file to be genrated. Default is one MB .PARAMETER Filecontent Possible values are <random> or <empty> When <random> is specified the file is filled with random values. The value <empty> fills the file with nulls. .PARAMETER ShowProgress This parameter is optional and shows the progress of the file creation. .EXAMPLE New-Bigfile -Target C:\Temp\LF -Megabyte 10 -Filecontent random .EXAMPLE New-Bigfile -Target C:\Temp\LF\bigfile.txt -Megabyte 10 -Filecontent random .EXAMPLE New-Bigfile -Target C:\Temp\LF -Megabyte 10 -Filecontent empty #> [CmdletBinding(SupportsShouldProcess=$True)] param( [Parameter(Mandatory = $true, Position = 0)] [String]$Target, [Parameter(Mandatory = $false, Position = 1)] [ValidateRange(1, 5120)] [UInt16]$MegaByte = 1, [Parameter(Mandatory = $true,position = 2)] [ValidateSet("random","empty")] [string]$FileContent, [Switch]$ShowProgress ) If ([string]::IsNullOrEmpty([System.IO.Path]::GetDirectoryName("$target")) -eq $True) { Write-Output "Specify a directory or file including path!" Throw } If([string]::IsNullOrEmpty([System.IO.Path]::GetExtension("$target"))) { Write-Verbose "Provided input $target has no file extension, target is a folder" $fname = ("" + ([guid]::NewGuid()) + ".LF") Write-Verbose "Random generated filename: $fname" $Target = Join-path $Target $fname $folder = [System.IO.Path]::GetDirectoryName($target) If ((Test-path $folder) -eq $false) {If ($PSCmdlet.ShouldProcess("Directory does not exist, creating directory $folder ")) { New-Item -Path $folder -ItemType Directory | Out-Null}} } Else { If ((Test-path -Path $target) -eq $true) {Write-verbose "File $Target already exists, exiting to prevent overwrite" Break} Else {Write-Verbose "File $target does not exist yet"} # Check if the directory actually exists, if not create it $folder = [System.IO.Path]::GetDirectoryName($target) If ((Test-path $folder) -eq $false) {If ($PSCmdlet.ShouldProcess("Creating folder $folder")) {New-Item -Path $folder -ItemType Directory | Out-Null}} } $path = $Target $total = 1mb * $MegaByte $strings = $bytes = 0 If ($FileContent -eq "random") { If ($PSCmdlet.ShouldProcess("Creating random file $path with $Megabyte MB")) { # create the stream writer $sw = New-Object IO.streamWriter $path # get a 64 element Char[]; I added the - and _ to have 64 chars [char[]]$chars = 'azertyuiopqsdfghjklmwxcvbnAZERTYUIOPQSDFGHJKLMWXCVBN0123456789-_' 1..$MegaByte | ForEach-Object { # get 1MB of chars from 4 256KB strings 1..4 | ForEach-Object { # randomize all chars and... $rndChars = $chars | Get-Random -Count $chars.Count # ...join them in a string $str = -join $rndChars # repeat random string 4096 times to get a 256KB string $str_ = $str * 4kb # write 256KB string to file $sw.Write($str_) # show progress if ($ShowProgress) { $strings++ $bytes += $str_.Length Write-Progress -Activity "Writing String #$strings" -Status "$bytes Bytes written" -PercentComplete ($bytes / $total * 100) } # release resources by clearing string variables Clear-Variable str, str_ } } $sw.Close() $sw.Dispose() # release resources through garbage collection [GC]::Collect() } } Else { If ($PSCmdlet.ShouldProcess("Creating empty file $path with $Megabyte MB")) { # write 4K worth of data at a time $bufSize = 4096 $bytes = New-Object byte[] $bufSize $file = [System.IO.File]::Create("$path") # write the first block out to accommodate integer division truncation $file.Write($bytes, 0, $bufSize) for ($i = 0; $i -lt $Megabyte*1MB; $i = $i + $bufSize) { $file.Write($bytes, 0, $bufSize) if ($ShowProgress) { Write-Progress -Activity "Writing String #$strings" -Status "Bytes written" -PercentComplete ($i/($megabyte*1MB)*100 ) } } $file.Close() } } } |
Run the following command to create a dummy file of 10 MB with random content
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New-bigfile c:\temp\lf 10 random -Verbose |
Run the following command to create a dummy file dummy10mb.txt with random content
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New-bigfile c:\temp\lf\dummy10mb.txt 10 random -Verbose |
Run the following command to create a dummy file of 20 MB filled with zeros
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New-bigfile c:\temp\lf 20 empty-Verbose |
If you prefer to see what is going on, add the -Showprogress option. And last but not least the function also supports the -whatif option.
Thanks, but I found this method to be much quicker and simpler:
http://www.christiano.ch/wordpress/2010/03/13/powershell-creating-large-dummy-files-with-net/
$file = Read-Host “Enter File Path”
$size = Read-Host “Enter File Size followed by MB or GB (Example: 10MB or 10GB)”
$objFile = [io.file]::Create($file)
$objFile.SetLength((Invoke-Expression $size))
$objFile.Close()
Write-Host “File Created: $file Size: $size”
This is a good script.
However, is it possible to get it working with a UNC path ?
like in windows network “\\server\share”, or “\\192.168.1.1\share”
i also can’t mount the share as a networkdrive “z:\” and use that.
i get the same error at about line 39, telling me my path is empty.
< and > substitution at the beginning and end of the documentation section at the top break the script.