Powershell Remove-Item IF file already exists after Copy-item

Question

I need to add a safety net in my script. I'm trying to do a copy job based on a list of users provided through a txt file. Copy the files from that users home directory to a new location. Once the files are copied, check if the file exists in the new location. If yes, then Remove-Item.

Can someone help me? I just don't know how to implement the "if file exists" logic.

$username = Get-Content '.\users.txt'
foreach ($un in $username)
{
  $dest = "\\server\homedirs\$un\redirectedfolders"
  $source = "\\server\homedirs\$un"
  New-Item -ItemType Directory -Path $dest\documents, $dest\desktop

  Get-ChildItem $source\documents -Recurse -Exclude '*.msg' | Copy-Item -Destination $dest\documents
  Get-ChildItem $source\desktop -Recurse -Exclude '*.msg' | Copy-Item -Destination $dest\desktop

  Get-ChildItem $source\mydocuments, $source\desktop -Recurse -Exclude '*.msg' | Remove-Item -Recurse
}

majkinetor · Accepted Answer · 2015-02-09 13:35:26Z

42

The shortest way to delete file if it doesn't exist is NOT to use Test-Path but:

rm my_file.zip -ea ig

This is short version of

rm my_file.zip -ErrorAction Ignore

which is much more readable and more DRY then

if (Test-Path my_file.zip) { rm my_file.zip }

answered Feb 9, 2015 at 13:35

majkinetor

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6 Comments

Ohad Schneider Over a year ago

Not only is this more readable, it is also more correct. The pattern of testing for existence first is wrong because by the time Test-Path returns with a positive answer, the folder might already have been deleted, at which point calling a vanilla Remove-Item will throw an error.

majkinetor Over a year ago

I wasn't even aware of that and and you are totally right. One additional benefit is that it also clearly states the intention of the programmer - if I want to delete, testing for something before is a noise.

Ohad Schneider Over a year ago

On second thought, the problem here is that it might hide a different error. For example, the file might be there, but a permissions issue prevents you from deleting it. I'm not a PS expert, but a quick search turns up ErrorVariable which may come in useful in disambiguating such cases.

majkinetor Over a year ago

ErrorVariable or use -ea 0 (silently continues but records error) and check Error afterwards.

Dan Z Over a year ago

Having to check ErrorVariable defeats the purpose of making it shorter than with Test-Path. I like to do it this way: Get-ChildItem * -Include my_file.zip | Remove-Item. It saves me having to specify the filename twice

|

Adi Inbar · Accepted Answer · 2014-04-22 06:00:53Z

To answer your question per se, you can do it like this:

Get-ChildItem $source\mydocuments, $source\desktop -Recurse -Exclude '*.msg' | %{
  if (Test-Path ($_. -replace "^$([regex]::escape($source))","$dest")) {
    Remove-Item $_ -Recurse
  }
}

Test-Path returns $true if the file at the given path exists, otherwise $false.
$_ -replace "^$([regex]::escape($source))","$dest" converts the path of each source item you're enumerating with the corresponding destination path, by replacing $source at the beginning of the path with $dest.
The basic regex for the first argument to the -replace operator is ^$source (which means "match the value of $source at the beginning of the string"). However, you need to use [regex]::escape in case $source contains any regex special characters, which is in fact extremely likely with Windows paths, since they contain backslashes. For example, the value you've given here for $source contains \s, which in a regex means "any whitespace character". $([regex]::escape($source)) will interpolate the value of $source with any regex special characters properly escaped, so that you're matching the explicit value.

That said, if your purpose is to copy each item to a new location, and remove the original only if the copy to the new location is successful, it seems like you're reinventing the wheel. Why not just use Move-Item instead of Copy-Item?

Not directly related to the question, but rather than repeating the same command for each subdirectory, you can use a foreach loop:

foreach ($subdir in (echo documents desktop)) {
  # Whatever command you end up using to copy or move the items, 
  # using "$source\$subdir" and "$dest\$subdir" as the paths
}

Knows Not Much · Accepted Answer · 2014-04-21 23:20:40Z

2

Test-Path commandlet will help you check if the file exists

http://technet.microsoft.com/en-us/library/ee177015.aspx

answered Apr 21, 2014 at 23:20

Knows Not Much

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Comments

Martin · Accepted Answer · 2021-10-13 17:40:27Z

@Adi Inbar, I need to use a function like this because I need to move files to a remote session, and the Move-Item does not work when I tried -ToSession... only Copy-Item. The Key is that if the power or internet goes down, the script will delete the file even if it wasn't copied.

$username = "name"
$password = ConvertTo-SecureString "password" -AsPlainText -Force
$credential = New-Object System.Management.Automation.PSCredential -ArgumentList ($username, $password)
$Session = New-PSSession -ComputerName "IPAdress" -Credential $credential 
Copy-Item -Path C:\userPC_1\csv-output\*.csv  -Destination C:\userPC_2\Documents\Test_Scripts -ToSession $Session -Verbose
Get-PSSession | Remove-PSSession
Get-ChildItem -Path C:\userPC_1\csv-output\*.csv | Remove-Item -Force

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