PowerShell实现文件夹筛选、字符串匹配及TimeSpan时间转换的技术求助

Let’s break down your requirements step by step—filtering folders that match a specific string pattern, then using TimeSpan to extract days, hours, and minutes from their timestamp properties.

Step 1: Filter Folders with String Matching (Using ForEach-Object) #

Your existing command already retrieves folders starting with K, but we can enhance it with targeted string matching and process each item via PowerShell’s pipeline-based ForEach-Object.

For example, if you want to filter folders whose name contains "BK", add a Where-Object clause to narrow down results before processing:

cls
Get-ChildItem -Path '.\k*' -Recurse -Directory | 
    Where-Object { $_.Name -match "BK" } |  # Match folders with "BK" in their name
    Sort-Object -Property Name -Descending |
    ForEach-Object {
        # Capture folder details
        $folderName = $_.Name
        $creationTime = $_.CreationTime
        $lastWriteTime = $_.LastWriteTime
        
        # Calculate time elapsed since last modification (vs current time)
        $timeElapsed = (Get-Date) - $lastWriteTime
        
        # Extract days, hours, minutes directly from the TimeSpan object
        $days = $timeElapsed.Days
        $hours = $timeElapsed.Hours
        $minutes = $timeElapsed.Minutes
        
        # Output structured results
        [PSCustomObject]@{
            FolderName     = $folderName
            CreationTime   = $creationTime
            LastWriteTime  = $lastWriteTime
            DaysElapsed    = $days
            HoursElapsed   = $hours
            MinutesElapsed = $minutes
        }
    } | Format-Table -AutoSize

String Matching Options: #

• Use -match "BK" for regex-based matching (finds "BK" anywhere in the name). For exact matches, use -eq "ExactFolderName".
• PowerShell’s matching is case-insensitive by default; use -cmatch if you need case-sensitive regex matching.

Step 2: Correct TimeSpan Handling #

Your initial TimeSpan code had syntax errors (missing parentheses, incorrect variable assignments). The example above shows the proper approach:

• Subtract two datetime values (e.g., (Get-Date) - $lastWriteTime) to get a TimeSpan object directly.
• The TimeSpan object has built-in properties like Days, Hours, and Minutes—no need for manual truncation with Math::Truncate!

If you need to convert a raw decimal value (like total hours as a decimal) into a TimeSpan, use this method:

$totalHours = 123.75  # Example: 123 full hours + 45 minutes
$timeSpan = [TimeSpan]::FromHours($totalHours)
Write-Host "Days: $($timeSpan.Days), Hours: $($timeSpan.Hours), Minutes: $($timeSpan.Minutes)"

Step 3: Alternative: Traditional foreach Loop #

If you prefer a non-pipeline foreach loop instead of ForEach-Object, here’s how to structure it:

cls
# First, collect and filter the folders
$folders = Get-ChildItem -Path '.\k*' -Recurse -Directory | 
    Where-Object { $_.Name -match "BK" } |
    Sort-Object -Property Name -Descending

# Process each folder in a loop
foreach ($folder in $folders) {
    $timeElapsed = (Get-Date) - $folder.LastWriteTime
    [PSCustomObject]@{
        FolderName     = $folder.Name
        CreationTime   = $folder.CreationTime
        LastWriteTime  = $folder.LastWriteTime
        DaysElapsed    = $timeElapsed.Days
        HoursElapsed   = $timeElapsed.Hours
        MinutesElapsed = $timeElapsed.Minutes
    }
} | Format-Table -AutoSize

Key Notes: #

• Use [PSCustomObject] to create structured output that’s easy to read, sort, or export (e.g., to CSV with Export-Csv).
• If you need cumulative decimal values (like total days including hours/minutes), use TotalDays, TotalHours, or TotalMinutes properties of the TimeSpan object.

内容的提问来源于stack exchange，提问作者Arenas