2

I wrote the below PowerShell script to compress logs older than 30 days:

$LastWrite=(get-date).AddDays(-30).ToString("MM/dd/yyyy")

Get-ChildItem -Filter "server.log*" -Recurse -File | Where-Object 
{$_.LastWriteTime -le $LastWrite}

Now, I am unable to get a compress command in PowerShell via which I can compress (zip/tar) the server.log* files older than 30 days. Expecting a single command which I can use by adding a pipe sign in the above command.

Luke Girvin
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user2781150
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2 Answers2

3

You can use the Compress-Archive cmdlet to zip files if you have PowerShell version 5 or above:

$LastWrite = (get-date).AddDays(-30)

$Files = Get-ChildItem -Filter "server.log*" -Recurse -File | Where-Object {$_.LastWriteTime -le $LastWrite}

ForEach ($File in $Files) {
    $File | Compress-Archive -DestinationPath "$($File.fullname).zip"
}
Mark Wragg
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    `.ToString("MM/dd/yyyy")` is not needed. `LastWriteTime` is a `DateTime` type, the same as the output of `Get-Date`, so they can be compared directly. – boxdog Dec 12 '18 at 10:41
  • The above answer is useful in case of powershell version 5 or above. For below version, I used below compress command:- $File | jar -cvMf "$($File.fullname).zip" $File – user2781150 Dec 18 '18 at 04:59
1

If you have an older version of Powershell you can use ZipFileExtensions' CreateEntryFromFile method, but there are a lot of considerations if you want a robust script that runs unattended.

In months of testing a script developed for this purpose, I encountered some issues that have made this small problem more complicated:

  1. Will any of the files be locked? CreateEntryFromFile may fail if so.
  2. Did you know that you can have multiple copies of the same file in a Zip archive? It's harder to extract them because you can't put them in the same folder. My script checks the file path and the archived file time stamp (+/- 2 seconds due to the lost date precision in Zip format) to determine if it's been already archived, and doesn't create a duplicate.
  3. Are the files created in a time zone with Daylight Savings? Zip format doesn't preserve that attribute, and may lose or gain an hour when uncompressed.
  4. Do you want to delete the original if it was successfully archived?
  5. If unsuccessful due to a locked/missing file or very long path, should the process continue?
  6. Will any error leave you with an unusable zip file? You need to Dispose() the archive to finalize it.
  7. How many archives do you want to keep? I prefer one per run-month, adding new entries to an existing zip.
  8. Do you want to preserve the relative path? Doing so will partially eliminate the problem of duplicates inside the zip file.

Mark Wragg's script should work if you don't care about these issues and you have Powershell 5, but it creates a zip for every log, which may not be what you want.

Here's the current version of the script - in case GitHub ever becomes unavailable:

#Sends $FileSpecs files to a zip archive if they match $Filter - deleting the original if $DeleteAfterArchiving is true. 
#Files that have already been archived will be ignored. 
param (
   [string] $ParentFolder = "$PSScriptRoot", #Files will be stored in the zip with path relative to this folder
   [string[]] $FileSpecs = @("*.log","*.txt","*.svclog","*.log.*"), 
   $Filter = { $_.LastWriteTime -lt (Get-Date).AddDays(-7)}, #a Where-Object function - default = older than 7 days
   [string] $ZipPath = "$PSScriptRoot\archive-$(get-date -f yyyy-MM).zip", #create one archive per run-month - it may contain older files 
   [System.IO.Compression.CompressionLevel]$CompressionLevel = [System.IO.Compression.CompressionLevel]::Optimal, 
   [switch] $DeleteAfterArchiving = $true,
   [switch] $Verbose = $true,
   [switch] $Recurse = $true
)
@( 'System.IO.Compression','System.IO.Compression.FileSystem') | % { [void][System.Reflection.Assembly]::LoadWithPartialName($_) }
Push-Location $ParentFolder #change to the folder so we can get relative path
$FileList = (Get-ChildItem $FileSpecs -File -Recurse:$Recurse  | Where-Object $Filter) #CreateEntryFromFile raises UnauthorizedAccessException if item is a directory
$totalcount = $FileList.Count
$countdown = $totalcount
$skipped = @()
Try{
    $WriteArchive = [IO.Compression.ZipFile]::Open( $ZipPath, [System.IO.Compression.ZipArchiveMode]::Update)
    ForEach ($File in $FileList){
        Write-Progress -Activity "Archiving files" -Status  "Archiving file $($totalcount - $countdown) of $totalcount : $($File.Name)"  -PercentComplete (($totalcount - $countdown)/$totalcount * 100)
        $ArchivedFile = $null
        $RelativePath = (Resolve-Path -LiteralPath "$($File.FullName)" -Relative) -replace '^.\\'
        $AlreadyArchivedFile = ($WriteArchive.Entries | Where-Object {#zip will store multiple copies of the exact same file - prevent this by checking if already archived. 
                (($_.FullName -eq $RelativePath) -and ($_.Length -eq $File.Length) )  -and 
                ([math]::Abs(($_.LastWriteTime.UtcDateTime - $File.LastWriteTimeUtc).Seconds) -le 2) #ZipFileExtensions timestamps are only precise within 2 seconds. 
            })     
        If($AlreadyArchivedFile -eq $null){
            If($Verbose){Write-Host "Archiving $RelativePath $($File.LastWriteTimeUtc -f "yyyyMMdd-HHmmss") $($File.Length)" }
            Try{
                $ArchivedFile = [System.IO.Compression.ZipFileExtensions]::CreateEntryFromFile($WriteArchive, $File.FullName, $RelativePath, $CompressionLevel)
            }Catch{
                Write-Warning  "$($File.FullName) could not be archived. `n $($_.Exception.Message)"  
                $skipped += [psobject]@{Path=$file.FullName; Reason=$_.Exception.Message}
            }
            If($File.LastWriteTime.IsDaylightSavingTime() -and $ArchivedFile){#HACK: fix for buggy date - adds an hour inside archive when the zipped file was created during PDT (files created during PST are not affected).  Not sure how to introduce DST attribute to file date in the archive. 
                $entry = $WriteArchive.GetEntry($RelativePath)    
                $entry.LastWriteTime = ($File.LastWriteTime.ToLocalTime() - (New-TimeSpan -Hours 1)) #TODO: This is better, but maybe not fully correct. Does it work in all time zones?
            }
        }Else{#Write-Warning "$($File.FullName) is already archived$(If($DeleteAfterArchiving){' and will be deleted.'}Else{'. No action taken.'})" 
            Write-Warning "$($File.FullName) is already archived - No action taken." 
            $skipped += [psobject]@{Path=$file.FullName; Reason="Already archived"}
        }
        If((($ArchivedFile -ne $null) -and ($ArchivedFile.FullName -eq $RelativePath)) -and $DeleteAfterArchiving) { #delete original if it's been successfully archived. 
            Try {
                Remove-Item $File.FullName -Verbose:$Verbose
            }Catch{
                Write-Warning "$($File.FullName) could not be deleted. `n $($_.Exception.Message)"
            }
        } 
        $countdown = $countdown -1
    }
}Catch [Exception]{
    Write-Error $_.Exception
}Finally{
    $WriteArchive.Dispose() #close the zip file so it can be read later 
    Write-Host "Sent $($totalcount - $countdown - $($skipped.Count)) of $totalcount files to archive: $ZipPath"
    $skipped | Format-Table -Autosize -Wrap
}
Pop-Location

Here's a command line that will compress all server.log* files older than 30 days under the current folder:

.\ArchiveOldLogs.ps1 -FileSpecs @("server.log*") -Filter { $_.LastWriteTime -lt (Get-Date).AddDays(-30)}
Rich Moss
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