Get-Tail

Author: ili101

Examples/Example1.png

@@ -0,0 +1,106 @@
+#requires -Version 3
+
+function Get-Tail
+{
+    <#
+            .SYNOPSIS
+            Tail command
+            .DESCRIPTION
+            Can tail files and wait on multiple files unlike Get-Content -Wait
+            .PARAMETER Path
+            Paths to log files
+            .PARAMETER Tail
+            number of lines to tail (0 for none)
+            .PARAMETER RefreshRate
+            Refresh interval
+    #>
+    [CmdletBinding()]
+    param
+    (
+        [Parameter(Mandatory, Position = 0,ValueFromPipeline=$true)]
+        [string[]]$Path,
+
+        [Parameter(Position = 1)]
+        [Int32]$Tail = 10,
+
+        [Parameter(Position = 2)]
+        [Int32]$RefreshRate = 100
+    )
+    
+    #check if pipeline or path variable
+    if ($Input)
+    {
+        [string[]]$Paths = $Input
+    }
+    else
+    {
+        $Paths = $Path
+    }
+
+    #create Readers
+    $Files = @{}
+    foreach ($Path in $Paths)
+    {
+        $Reader = New-Object -TypeName System.IO.StreamReader -ArgumentList (New-Object -TypeName IO.FileStream -ArgumentList ($Path, [System.IO.FileMode]::Open, [System.IO.FileAccess]::Read, [IO.FileShare]::ReadWrite))
+        #get end the file
+        $LastMaxOffset = $Reader.BaseStream.Length
+        #get encoding
+        $null = $Reader.Readline()
+        $Reader.DiscardBufferedData()
+        #seek to the last max offset
+        $null = $Reader.BaseStream.Seek($LastMaxOffset, [System.IO.SeekOrigin]::Begin)
+      
+        $Files.Add($Path, (New-Object -TypeName PSObject -Property (@{
+                        'Reader'      = $Reader
+                        'LastMaxOffset' = $LastMaxOffset
+        })))
+    }
+    
+    #tail existing lines
+    if ($Tail -gt 0)
+    {
+        foreach ($Path in $Paths)
+        {
+            Write-Host -ForegroundColor Green -Object $Path
+            Get-Content -Path $Path -Tail $Tail
+        }
+        $LastFile = $Path
+    }
+    else
+    {
+        $LastFile = $null
+    }
+    
+    #tail new lines
+    :ReaderLoop while ($true)
+    {
+        Start-Sleep -Milliseconds $RefreshRate
+        foreach ($File in $Files.GetEnumerator())
+        {
+            #if the file size has not changed, idle
+            if ($File.Value.Reader.BaseStream.Length -eq $File.Value.LastMaxOffset)
+            {
+                continue
+            }
+            
+            if ($LastFile -ne $File.name)
+            {
+                Write-Host -ForegroundColor Green -Object $File.name
+                $LastFile = $File.name
+            }
+            
+            #read out of the file until the EOF
+            while (($Line = $File.Value.Reader.ReadLine()) -ne $null)
+            {
+                $Line
+            }
+            #update the last max offset
+            $File.Value.LastMaxOffset = $File.Value.Reader.BaseStream.Position
+        }
+    }
+}
+
+<#
+Get-Tail -Path C:\Windows\WindowsUpdate.log,C:\Windows\win.ini
+Get-ChildItem -Path C:\Windows\win.ini,C:\Windows\*.log -Exclude PFRO.log | Get-Tail -Tail 5
+#>

Get-Tail.ps1

@@ -22,3 +22,12 @@ Get-PaddedCenter -Title 'End',(Get-Date)
 Get-PaddedCenter -Title 'Test' -Separator $null -Width 8 -Pad ([char]35)
 ##Test##
 ```
+
+## Get-Tail
+tail files and wait, support multiple files unlike Get-Content -Wait
+##### Examples
+```PowerShell
+Get-Tail -Path C:\Windows\WindowsUpdate.log,C:\Windows\win.ini
+Get-ChildItem -Path C:\Windows\win.ini,C:\Windows\*.log -Exclude PFRO.log | Get-Tail -Tail 5
+```
+![](https://raw.githubusercontent.com/ili101/PowerShell/master/Examples/Example1.png)