Powershell script to delete oldest files (not relative to current date)

Usage: yourScript.ps1 -Path path\to\run\against [-NumberToSave N]

param([String]$Path,[Int32]$NumberToSave=5)

$items = Get-ChildItem "$Path\*.ext" |
    Where-Object Name -match "\d\d\d\d\d\d\d\d-\d\d\d\d\.ext" |
    Sort-Object Name -Descending

if ($NumberToSave -lt $items.Count)
{
    $items[$NumberToSave..($items.Count-1)] | Remove-Item
}

I don't expect this is really any better than @John's, I just made this to try parameters, regexp, and not using a loop. Doing a regex match does have the possible benefit of ruling out other files with .ext that don't match the format (e.g. 20130504-1200.txt.ext, 20.ext), but it's doubtful that applies.

I was bummed to find out that if $NumberToSave = $items.Count then the if statement is needed, otherwise it wouldn't be there. Technically:

$items[$numberToSave..$items.Count] | Remove-Item 

works fine (PowerShell doesn't seem to error if you reference past the array bounds, it just handles and ignores it?) but that seemed potentially confusing.

$n = x

$items = Get-ChildItem path_to_folder\*.ext

$items | 
  Sort-Object Name -Descending | 
  Select-Object -Last ($items.count - $n) | 
  Foreach-Object { Remove-Item $_ }

A friend provided this script:

# Defines how many files you want to keep?
$Keep = 5

# Specifies file mask
$FileMask = "*.ext"

# Defines base directory path
$Path = "F:\path\to\backups\"

# Creates a full path plus file mask value
$FullPath = $Path + $FileMask

# Creates an array of all files of a file type within a given folder, reverse sort.
$allFiles = @(Get-ChildItem $FullPath) | SORT Name -descending 

# Checks to see if there is even $Keep files of the given type in the directory.
If ($allFiles.count -gt $Keep) {

    # Creates a new array that specifies the files to delete, a bit ugly but concise.
    $DeleteFiles = $allFiles[$($allFiles.Count - ($allFiles.Count - $Keep))..$allFiles.Count]

    # ForEach loop that goes through the DeleteFile array
    ForEach ($DeleteFile in $DeleteFiles) {

        # Creates a full path and delete file value
        $dFile = $Path + $DeleteFile.Name

        # Deletes the specified file
        Remove-Item $dFile
    }
}

# Get all the items in `C:\Archive`
Get-ChildItem -Path 'C:\Archive' |

    # Skip directories
    Where-Object { -not $_.PsIsContainer } |

    # Only get files that match YYYYMMDD-HHMM.ext format
    Where-Object { $_.Name -match '\d{8}-\d{4}.ext' } |

    # Sort them by name, from most recent to oldest
    Sort-Object -Descending -Property Name |

    # Keep the first five items
    Select-Object -Skip 5 |

    Remove-Item -WhatIf

This works for me using powershell v5.1

Get-ChildItem -Path C:\Path\To\Logs\BaseName*.log | Sort-Object -Descending | Select-Object -Skip 5 | Remove-Item

I've done this in Bash before, and you may be able to translate it to PowerShell. Personally, I'm a Linux admin, and don't know enough about Windows/PowerShell to do so myself.

#!/bin/bash

# Directory with backups in need of cleaning
bkps_dir="/opt/bkps/hosting.madyork.com"

# Make sure that there are at least 7 days worth of backups to avoid removing
#   the only backups left.
if [ "$(/bin/find "${bkps_dir}" -maxdepth 1 -type d | /usr/bin/wc -l)" -lt 8 ]; then
    echo "Less than 8 backups found!"
    echo "Will not delete anything!"
    echo "Exiting..."
    exit 1
fi

/bin/find "${bkps_dir}" -maxdepth 1 -type d -mtime +7 -print0 | /usr/bin/xargs -0 /bin/rm -rf

Sorry that I could not be more helpful.

Edit: I also placed this here in case a Linux admin is in need of similar info.