Get-ChildItem error handling when using long file paths - powershell

I am trying to handle errors when scanning through folders. Let's say I have something like:
Get-ChildItem $somepath -Directory | ForEach-Object {
if(error occurred due to too long path) {
skip this folder then
} else {
Write-Host $_.BaseName
}
}
When I do this I print the folders in $somepath until one of them is too long and then the loop stops. Even when using SilentlyContinue. I want to print even after reaching a folder that is too long.

If you can install a non-ancient PowerShell version (3.0 or newer), simply prepend the path with \\?\ to overcome the 260-character limit for full path:
Get-ChildItem "\\?\$somepath" | ForEach {
# ............
}

You could try ignoring the files longer 260 characters by using the Where-Object cmdlet.
Get-ChildItem $somepath -Directory -ErrorAction SilentlyContinue `
| Where-Object {$_.length -lt 261} `
| ForEach-Object { Write-Host $_.BaseName }
Or you could use the following (Ref).
cmd /c dir $somepath /s /b | Where-Object {$_.length -lt 261}

I will add my solution since the neither on this page worked for me. I am using relative paths, so I can't use the \\ prefix.
$TestFiles = Get-ChildItem $pwd "*Tests.dll" -Recurse | Where-Object {$_.FullName.length -lt 261} | Select-Object FullName -ExpandProperty FullName | Where-Object FullName -like "*bin\Release*"
Write-Host "Found TestFiles:"
foreach ($TestFile in $TestFiles) {
Write-Host " $TestFile"
}

Related

The specified path, file name, or both are too long Powershell

I have the below line in my powershell script in windows 7
$subFolderItems = Get-ChildItem $i.FullName -recurse -force | Where-Object {$_.PSIsContainer -eq $false} | Measure-Object -property Length -sum | Select-Object Sum
The problem I get this error The specified path, file name, or both are too long in some of the files.
I looked into it and found some suggestions to add \\?\ before the file path I tried as below and it's not working any advice?
$Base = '\\?\'
$subFolderItems = Get-ChildItem $Base$i.FullName -recurse -force | Where-Object {$_.PSIsContainer -eq $false} | Measure-Object -property Length -sum | Select-Object Sum
As you have commented, the path in $i.FullName is in UNC format (\\server\share\restofpath).
In that case, the prefix for long path should be \\?\UNC\ and the first two backslashes of the path itself need to be removed. In your case, it should be:
\\?\UNC\rackstation.mydom.com\main\sub.arch\mydom-customers\John_Marcus-123456
Using this prefix only works with the -LiteralPath parameter of Get-ChildItem.
Try
Get-ChildItem -LiteralPath ('\\?\UNC\' + $i.FullName.Substring(2))
For things like this, I always keep a small helper function handy:
function Add-LongPathPrefix([string] $Path) {
if ([string]::IsNullOrWhiteSpace($Path) -or $Path.StartsWith('\\?\')) { #'# nothing to do here
return $Path
}
if ($Path.StartsWith('\\')) {
# it's a UNC path like \\server\share\restofpath
return '\\?\UNC\' + $Path.Substring(2) #'# --> \\?\UNC\server\share\restofpath
}
else {
# it's a local path like X:\restofpath
return '\\?\' + $Path #'# --> \\?\X:\restofpath
}
}
Use it like this:
Get-ChildItem -LiteralPath (Add-LongPathPrefix $i.FullName)
P.S. For this you need to have Powershell 5.1 or higher
Hope that helps

Compare-Object Delete File if file does not exist on source

I have this PowerShell code that compares 2 directories and removes files if the files no longer exist in the source directory.
For example say I have Folder 1 & Folder 2. I want to compare Folder 1 with Folder 2, If a file doesn't exist anymore in Folder 1 it will remove it from Folder 2.
this code works ok but I have a problem where it also picks up file differences on the date/time. I only want it to pick up a difference if the file doesn't exist anymore in Folder 1.
Compare-Object $source $destination -Property Name -PassThru | Where-Object {$_.SideIndicator -eq "=>"} | % {
if(-not $_.FullName.PSIsContainer) {
UPDATE-LOG "File: $($_.FullName) has been removed from source"
Remove-Item -Path $_.FullName -Force -ErrorAction SilentlyContinue
}
}
Is there an extra Where-Object {$file1 <> $file2} or something like that.?
I am not sure how you are getting the information for $source and $destination I am assuming you are using Get-ChildItem
What i would do to eliminate the issue with date/time would be to not capture it in these variables. For Example:
$source = Get-ChildItem C:\temp\Folder1 -Recurse | select -ExpandProperty FullName
$destination = Get-ChildItem C:\temp\Folder2 -Recurse | select -ExpandProperty FullName
By doing this you only get the FullName Property for each object that is a child item not the date/time.
You would need to change some of the script after doing this for it to still work.
If I am not getting it wrong, the issue is your code is deleting the file with different time-stamp as compared to source:
Did you try -ExcludeProperty?
$source = Get-ChildItem "E:\New folder" -Recurse | select -ExcludeProperty Date
The following script can serve your purpose
$Item1=Get-ChildItem 'SourcePath'
$Item2=Get-ChildItem 'DestinationPath'
$DifferenceItem=Compare-Object $Item1 $Item2
$ItemToBeDeleted=$DifferenceItem | where {$_.SideIndicator -eq "=>" }
foreach ($item in $ItemToBeDeleted)
{
$FullPath=$item.InputObject.FullName
Remove-Item $FullPath -Force
}
Try something like this
In PowerShell V5:
$yourdir1="c:\temp"
$yourdir2="c:\temp2"
$filesnamedir1=(gci $yourdir1 -file).Name
gci $yourdir2 -file | where Name -notin $filesnamedir1| remove-item
In old PowerShell:
$yourdir1="c:\temp"
$yourdir2="c:\temp2"
$filesnamedir1=(gci $yourdir1 | where {$_.psiscontainer -eq $false}).Name
gci $yourdir2 | where {$_.psiscontainer -eq $false -and $_.Name -notin $filesnamedir1} | remove-item
If you want to compare files in multiple dir, use the -recurse option for every gci command.

How to recursively remove all empty folders in PowerShell?

I need to recursively remove all empty folders for a specific folder in PowerShell (checking folder and sub-folder at any level).
At the moment I am using this script with no success.
Could you please tell me how to fix it?
$tdc='C:\a\c\d\'
$a = Get-ChildItem $tdc -recurse | Where-Object {$_.PSIsContainer -eq $True}
$a | Where-Object {$_.GetFiles().Count -eq 0} | Select-Object FullName
I am using PowerShell on Windows 8.1 version.
You need to keep a few key things in mind when looking at a problem like this:
Get-ChildItem -Recurse performs head recursion, meaning it returns folders as soon as it finds them when walking through a tree. Since you want to remove empty folders, and also remove their parent if they are empty after you remove the empty folders, you need to use tail recursion instead, which processes the folders from the deepest child up to the root. By using tail recursion, there will be no need for repeated calls to the code that removes the empty folders -- one call will do it all for you.
Get-ChildItem does not return hidden files or folders by default. As a result you need to take extra steps to ensure that you don't remove folders that appear empty but that contain hidden files or folders. Get-Item and Get-ChildItem both have a -Force parameter which can be used to retrieve hidden files or folders as well as visible files or folders.
With those points in mind, here is a solution that uses tail recursion and that properly tracks hidden files or folders, making sure to remove hidden folders if they are empty and also making sure to keep folders that may contain one or more hidden files.
First this is the script block (anonymous function) that does the job:
# A script block (anonymous function) that will remove empty folders
# under a root folder, using tail-recursion to ensure that it only
# walks the folder tree once. -Force is used to be able to process
# hidden files/folders as well.
$tailRecursion = {
param(
$Path
)
foreach ($childDirectory in Get-ChildItem -Force -LiteralPath $Path -Directory) {
& $tailRecursion -Path $childDirectory.FullName
}
$currentChildren = Get-ChildItem -Force -LiteralPath $Path
$isEmpty = $currentChildren -eq $null
if ($isEmpty) {
Write-Verbose "Removing empty folder at path '${Path}'." -Verbose
Remove-Item -Force -LiteralPath $Path
}
}
If you want to test it here's code that will create interesting test data (make sure you don't already have a folder c:\a because it will be deleted):
# This creates some test data under C:\a (make sure this is not
# a directory you care about, because this will remove it if it
# exists). This test data contains a directory that is hidden
# that should be removed as well as a file that is hidden in a
# directory that should not be removed.
Remove-Item -Force -Path C:\a -Recurse
New-Item -Force -Path C:\a\b\c\d -ItemType Directory > $null
$hiddenFolder = Get-Item -Force -LiteralPath C:\a\b\c
$hiddenFolder.Attributes = $hiddenFolder.Attributes -bor [System.IO.FileAttributes]::Hidden
New-Item -Force -Path C:\a\b\e -ItemType Directory > $null
New-Item -Force -Path C:\a\f -ItemType Directory > $null
New-Item -Force -Path C:\a\f\g -ItemType Directory > $null
New-Item -Force -Path C:\a\f\h -ItemType Directory > $null
Out-File -Force -FilePath C:\a\f\test.txt -InputObject 'Dummy file'
Out-File -Force -FilePath C:\a\f\h\hidden.txt -InputObject 'Hidden file'
$hiddenFile = Get-Item -Force -LiteralPath C:\a\f\h\hidden.txt
$hiddenFile.Attributes = $hiddenFile.Attributes -bor [System.IO.FileAttributes]::Hidden
Here's how you use it. Note that this will remove the top folder (the C:\a folder in this example, which gets created if you generated the test data using the script above) if that folder winds up being empty after deleting all empty folders under it.
& $tailRecursion -Path 'C:\a'
You can use this:
$tdc="C:\a\c\d"
$dirs = gci $tdc -directory -recurse | Where { (gci $_.fullName).count -eq 0 } | select -expandproperty FullName
$dirs | Foreach-Object { Remove-Item $_ }
$dirs will be an array of empty directories returned from the Get-ChildItem command after filtering. You can then loop over it to remove the items.
Update
If you want to remove directories that contain empty directories, you just need to keep running the script until they're all gone. You can loop until $dirs is empty:
$tdc="C:\a\c\d"
do {
$dirs = gci $tdc -directory -recurse | Where { (gci $_.fullName).count -eq 0 } | select -expandproperty FullName
$dirs | Foreach-Object { Remove-Item $_ }
} while ($dirs.count -gt 0)
If you want to ensure that hidden files and folders will also be removed, include the -Force flag:
do {
$dirs = gci $tdc -directory -recurse | Where { (gci $_.fullName -Force).count -eq 0 } | select -expandproperty FullName
$dirs | Foreach-Object { Remove-Item $_ }
} while ($dirs.count -gt 0)
Get-ChildItem $tdc -Recurse -Force -Directory |
Sort-Object -Property FullName -Descending |
Where-Object { $($_ | Get-ChildItem -Force | Select-Object -First 1).Count -eq 0 } |
Remove-Item -Verbose
The only novel contribution here is using Sort-Object to reverse sort by the directory's FullName. This will ensure that we always process children before we process parents (i.e., "tail recursion" as described by Kirk Munro's answer). That makes it recursively remove empty folders.
Off hand, I'm not sure if the Select-Object -First 1 will meaningfully improve performance or not, but it may.
Just figured I would contribute to the already long list of answers here.
Many of the answers have quirks to them, like needing to run more than once. Others are overly complex for the average user (like using tail recursion to prevent duplicate scans, etc).
Here is a very simple one-liner that I've been using for years, and works great...
It does not account for hidden files/folders, but you can fix that by adding -Force to the Get-ChildItem command
This is the long, fully qualified cmdlet name version:
Get-ChildItem -Recurse -Directory | ? { -Not ($_.EnumerateFiles('*',1) | Select-Object -First 1) } | Remove-Item -Recurse
So basically...here's how it goes:
Get-ChildItem -Recurse -Directory - Start scanning recursively looking for directories
$_.EnumerateFiles('*',1) - For each directory...Enumerate the files
EnumerateFiles will output its findings as it goes, GetFiles will output when it is done....at least, that's how it is supposed to work in .NET...for some reason in PowerShell GetFiles starts spitting out immediately. But I still use EnumerateFiles because in testing it was reliably faster.
('*',1) means find ALL files recursively.
| Select-Object -First 1 - Stop at the first file found
This was difficult to test how much it helped. In some cases it helped tremendously, other times it didn't help at all, and in some cases it slowed it down by a small amount. So I really don't know. I guess this is optional.
| Remove-Item -Recurse - Remove the directory, recursively (ensures directories that contain empty sub directories gets removed)
If you're counting characters, this could be shortened to:
ls -s -ad | ? { -Not ($_.EnumerateFiles('*',1) | select -First 1) } | rm -Recurse
-s - alias for -Recurse
-ad - alias for -Directory
If you really don't care about performance because you don't have that many files....even more so to:
ls -s -ad | ? {!($_.GetFiles('*',1))} | rm -Recurse
Side note:
While playing around with this, I started testing various versions with Measure-Command against a server with millions of files and thousands of directories.
This is faster than the command I've been using (above):
(gi .).EnumerateDirectories('*',1) | ? {-Not $_.EnumerateFiles('*',1) } | rm -Recurse
ls c:\temp -rec |%{ if ($_.PSIsContainer -eq $True) {if ( (ls $_.fullname -rec | measure |select -expand count ) -eq "0" ){ ri $_.fullname -whatif} } }
Assuming you're inside the parent folder of interest
gci . -Recurse -Directory | % { if(!(gci -Path $_.FullName)) {ri -Force -Recurse $_.FullName} }
For your case with $tdc it'll be
gci $tdc -Recurse -Directory | % { if(!(gci -Path $_.FullName)) {ri -Force -Recurse $_.FullName} }
If you just want to make sure, that you delete only folders that may contain subfolders but no files within itself and its subfolders, this may be an easier an quicker way.
$Empty = Get-ChildItem $Folder -Directory -Recurse |
Where-Object {(Get-ChildItem $_.FullName -File -Recurse -Force).Count -eq 0}
Foreach ($Dir in $Empty)
{
if (test-path $Dir.FullName)
{Remove-Item -LiteralPath $Dir.FullName -recurse -force}
}
Recursively removing empty subdirectories can also be accomplished using a "For Loop".
Before we start, let's make some subdirectories & text files to work with in $HOME\Desktop\Test
MD $HOME\Desktop\Test\0\1\2\3\4\5
MD $HOME\Desktop\Test\A\B\C\D\E\F
MD $HOME\Desktop\Test\A\B\C\DD\EE\FF
MD $HOME\Desktop\Test\Q\W\E\R\T\Y
MD $HOME\Desktop\Test\Q\W\E\RR
"Hello World" > $HOME\Desktop\Test\0\1\Text1.txt
"Hello World" > $HOME\Desktop\Test\A\B\C\D\E\Text2.txt
"Hello World" > $HOME\Desktop\Test\A\B\C\DD\Text3.txt
"Hello World" > $HOME\Desktop\Test\Q\W\E\RR\Text4.txt
First, store the following Script Block in the variable $SB. The variable can be called later using the &SB command. The &SB command will output a list of empty subdirectories contained in $HOME\Desktop\Test
$SB = {
Get-ChildItem $HOME\Desktop\Test -Directory -Recurse |
Where-Object {(Get-ChildItem $_.FullName -Force).Count -eq 0}
}
NOTE: The -Force parameter is very important. It makes sure that directories which contain hidden files and subdirectories, but are otherwise empty, are not deleted in the "For Loop".
Now use a "For Loop" to recursively remove empty subdirectories in $HOME\Desktop\Test
For ($Empty = &$SB ; $Empty -ne $null ; $Empty = &$SB) {Remove-Item (&$SB).FullName}
Tested as working on PowerShell 4.0
I have adapted the script of RichardHowells.
It doesn't delete the folder if there is a thumbs.db.
##############
# Parameters #
##############
param(
$Chemin = "" , # Path to clean
$log = "" # Logs path
)
###########
# Process #
###########
if (($Chemin -eq "") -or ($log-eq "") ){
Write-Error 'Parametres non reseignes - utiliser la syntaxe : -Chemin "Argument" -log "argument 2" ' -Verbose
Exit
}
#loging
$date = get-date -format g
Write-Output "begining of cleaning folder : $chemin at $date" >> $log
Write-Output "------------------------------------------------------------------------------------------------------------" >> $log
<########################################################################
define a script block that will remove empty folders under a root folder,
using tail-recursion to ensure that it only walks the folder tree once.
-Force is used to be able to process hidden files/folders as well.
########################################################################>
$tailRecursion = {
param(
$Path
)
foreach ($childDirectory in Get-ChildItem -Force -LiteralPath $Path -Directory) {
& $tailRecursion -Path $childDirectory.FullName
}
$currentChildren = Get-ChildItem -Force -LiteralPath $Path
Write-Output $childDirectory.FullName
<# Suppression des fichiers Thumbs.db #>
Foreach ( $file in $currentchildren )
{
if ($file.name -notmatch "Thumbs.db"){break}
if ($file.name -match "Thumbs.db"){
Remove-item -force -LiteralPath $file.FullName}
}
$currentChildren = Get-ChildItem -Force -LiteralPath $Path
$isEmpty = $currentChildren -eq $null
if ($isEmpty) {
$date = get-date -format g
Write-Output "Removing empty folder at path '${Path}'. $date" >> $log
Remove-Item -Force -LiteralPath $Path
}
}
# Invocation of the script block
& $tailRecursion -Path $Chemin
#loging
$date = get-date -format g
Write-Output "End of cleaning folder : $chemin at $date" >> $log
Write-Output "------------------------------------------------------------------------------------------------------------" >> $log
Something like this works for me. The script delete empty folders and folders containing only folder (no files, no hidden files).
$items = gci -LiteralPath E:\ -Directory -Recurse
$dirs = [System.Collections.Generic.HashSet[string]]::new([string[]]($items |% FullName))
for (;;) {
$remove = $dirs |? { (gci -LiteralPath $_ -Force).Count -eq 0 }
if ($remove) {
$remove | rm
$dirs.ExceptWith( [string[]]$remove )
}
else {
break
}
}
I wouldn't take the comments/1st post to heart unless you also want to delete files that are nested more than one folder deep. You are going to end up deleting directories that may contain directories that may contain files. This is better:
$FP= "C:\Temp\"
$dirs= Get-Childitem -LiteralPath $FP -directory -recurse
$Empty= $dirs | Where-Object {$_.GetFiles().Count -eq 0 **-and** $_.GetDirectories().Count -eq 0} |
Select-Object FullName
The above checks to make sure the directory is in fact empty whereas the OP only checks to make sure there are no files. That in turn would result in files nexted a few folders deep also being deleted.
You may need to run the above a few times as it won't delete Dirs that have nested Dirs. So it only deletes the deepest level. So loop it until they're all gone.
Something else I do not do is use the -force parameter. That is by design. If in fact remove-item hits a dir that is not empty you want to be prompted as an additional safety.
$files = Get-ChildItem -Path c:\temp -Recurse -Force | where psiscontainer ; [array]::reverse($files)
[Array]::reverse($files) will reverse your items, so you get the lowest files in hierarchy first.
I use this to manipulate filenames that have too long filepaths, before I delete them.
This is a simple approach
dir -Directory | ? { (dir $_).Count -eq 0 } | Remove-Item
This will remove up all empty folders in the specified directory $tdc.
It is also a lot faster since there's no need for multiple runs.
$tdc = "x:\myfolder" # Specify the root folder
gci $tdc -Directory -Recurse `
| Sort-Object { $_.FullName.Length } -Descending `
| ? { $_.GetFiles().Count -eq 0 } `
| % {
if ($_.GetDirectories().Count -eq 0) {
Write-Host " Removing $($_.FullName)"
$_.Delete()
}
}
#By Mike Mike Costa Rica
$CarpetasVacias = Get-ChildItem -Path $CarpetaVer -Recurse -Force -Directory | Where {(gci $_.fullName).count -eq 0} | select Fullname,Name,LastWriteTime
$TotalCarpetas = $CarpetasVacias.Count
$CountSu = 1
ForEach ($UnaCarpeta in $CarpetasVacias){
$RutaCarp = $UnaCarpeta.Fullname
Remove-Item -Path $RutaCarp -Force -Confirm:$False -ErrorAction Ignore
$testCar = Test-Path $RutaCarp
if($testCar -eq $true){
$Datem = (Get-Date).tostring("MM-dd-yyyy HH:mm:ss")
Write-Host "$Datem ---> $CountSu de $TotalCarpetas Carpetas Error Borrando Directory: $RutaCarp" -foregroundcolor "red"
}else{
$Datem = (Get-Date).tostring("MM-dd-yyyy HH:mm:ss")
Write-Host "$Datem ---> $CountSu de $TotalCarpetas Carpetas Correcto Borrando Directory: $RutaCarp" -foregroundcolor "gree"
}
$CountSu += 1
}

Powershell compare-object

I trying to make a script which compare two directory ( source, destination) and if there are a difference on destination, copy files from source to destination.
The problem is that I don't know how copy the tree of files too.
Example:
$s = "C:\source\client"
$t = "C:\destination\client"
$target = Get-ChildItem $t -Recurse
$source = get-childitem $s -Recurse
Compare-Object $source $target -Property Name , Length |
Where-Object { $_.SideIndicator -eq '<=' } |
foreach-object -process{
copy-item $_.FullName -destination $t
}
If I have a file in source ( C:\source\client\bin\file.txt) and not in the destination folder, how is the code to copy the file in C:\destination\client\bin\file.txt ?
Thanks.
I am in the process of testing this more. From what i can see the logic of your code is sound.
Compare-Object $source $target -Property Name , Length |
Where-Object { $_.SideIndicator -eq '<=' } | Select-Object -ExpandProperty inputobject |
foreach-object -process{
copy-item $_.FullName -destination $t
}
Once you have the compare done pipe the results after the Where in Select-Object -ExpandProperty inputobject to extract the File item so that you can see the FullName property
copy-item has a -recurse parameter that will let you specify the root of a directory and then copy everything below it
copy-item c:\test d:\test -recurse -force
Edit:
The problem is for repeated tasks you can't stop it from trying to overwrite everything. You can add -force to make it do it, but it is not very efficient.
Alternatively (and probably a better and simpler way to go about this) you could call robocopy with the /mir switch
Thanks for sharing. Here is what I have done with everything I searched to compare MD5 and then copy only newly added and different files.
With [Compare contents of two folders using PowerShell Get-FileHash] from http://almoselhy.azurewebsites.net/2014/12/compare-contents-of-two-folders-using-powershell-get-filehash/
$LeftFolder = "D:\YFMS_Target"
$RightFolder = "D:\YFMS_Copy"
$LeftSideHash = #(Get-ChildItem $LeftFolder -Recurse | Get-FileHash -Algorithm MD5| select #{Label="Path";Expression={$_.Path.Replace($LeftFolder,"")}},Hash)
$RightSideHash = #(Get-ChildItem $RightFolder -Recurse | Get-FileHash -Algorithm MD5| select #{Label="Path";Expression={$_.Path.Replace($RightFolder,"")}},Hash)
robocopy $LeftFolder $RightFolder /e /xf *
Write-Host "robocopy LastExitCode: $LastExitCode"
if ($LastExitCode -gt 7) { exit $LastExitCode } else { $global:LastExitCode = $null }
Compare-Object $LeftSideHash $RightSideHash -Property Path,Hash | Where-Object { $_.SideIndicator -eq '<=' } | foreach { Copy-Item -LiteralPath (Join-Path $LeftFolder $_.Path) -Destination (Join-Path $RightFolder $_.Path) -verbose}

File extension while searching

I am trying to get a list of all my files with a specific extension.
(...)$_.Extension -eq ".$ext"
I read extension from console to script.
My question is how to find any file with an extension of .*?
Edit:
Here's the rest of the code:
$setOfFolders = (Get-ChildItem -Path D:\ -Directory).name
Write-host "Set last write date " -ForegroundColor Yellow -NoNewline
$ostZmiana= read-host $exten = read-host "Set extensions "
ForEach ($f in $setOfFolders)
{
$saveTofile = "C:\Users\pziolkowski\Desktop\Outs\$f.txt"
Get-ChildItem -Path D:\Urzad\Wspolny\$f -Recurse | ? {$_.LastAccessTime -lt $ostZmiana -and $_.Extension -eq ".$exten"} | % {Get-acl $_.FullName} |sort Owner | ft -AutoSize -Wrap Owner, #{Label="ShortPath"; Expression= $_.Path.Substring(38)}} > $saveToFile
}
You can also use the -filter on Get-ChildItem:
Get-ChildItem -Filter "*.txt"
And you can specifiy recursion too:
Get-ChildItem -Recurse -Filter "*.txt"
The $_.Extension will see the file as, (in the case of a text file) .txt
If $ext is currently a valid extension, then .$ext would look like ..txt echoed out.
The easiest way to get a list of files with a specific extension in PowerShell is one of two, really.
C like syntax:
$myList
Get-ChildItem |`
Foreach-Object {
if ($_.Extension -eq ".txt") { $myList += $_}
}
PowerShell style:
Get-ChildItem | Where-Object {$_.Extension -eq ".txt"} | Do stuff
To get all files, as most files have an extension, just use Get-ChildItem or GCI or ls. (GCI and LS are aliases for Get-ChildItem).
To get all files with an extension, but not a specific extension:
Get-ChildItem | Where-Object {$_.Extension}
This evaluates as a bool, so true or false.
These are off the cuff, but should get you going in the right direction.