Unix tail equivalent command in Windows Powershell

Question

I have to look at the last few lines of a large file  typical size is 500MB-2GB   I am looking for a equivalent of Unix command tail for Windows Powershell  A few alternatives available on are   http   tailforwin32 sourceforge net   and  Get-Content  filename    Select-Object -Last 10  For me  it is not allowed to use the first alternative  and the second alternative is slow  Does anyone know of an efficient implementation of tail for PowerShell

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For completeness I ll mention that Powershell 3 0 now has a -Tail flag on Get-Content  Get-Content   log log -Tail 10   gets the last 10 lines of the file  Get-Content   log log -Wait -Tail 10   gets the last 10 lines of the file and waits for more  Also  for those  nix users  note that most systems alias cat to Get-Content  so this usually works  cat   log log -Tail 10

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try Windows Server 2003 Resource Kit Tools  it contains a tail exe which can be run on Windows system   https   www microsoft com en-us download details aspx id 17657

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Use the -wait parameter with Get-Content  which displays lines as they are added to the file  This feature was present in PowerShell v1  but for some reason not documented well in v2   Here is an example  Get-Content -Path  C  scripts test txt  -Wait   Once you run this  update and save the file and you will see the changes on the console

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It is possible to download all of the UNIX commands compiled for Windows from this GitHub repository  https   github com George-Ogden UNIX

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Just some additions to previous answers  There are aliases defined for Get-Content  for example if you are used to UNIX you might like cat  and there are also type and gc  So instead of   Get-Content -Path  lt Path gt  -Wait -Tail 10   you can write    Print whole file and wait for appended lines and print them cat  lt Path gt  -Wait   Print last 10 lines and wait for appended lines and print them cat  lt Path gt  -Tail 10 -Wait

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Very basic  but does what you need without any addon modules or PS version requirements   while   true   Clear-Host  gc E  test txt   select -last 3  sleep 2

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Probably too late for an answere but  try this one  Get-Content  lt filename gt  -tail  lt number of items wanted gt

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I took  hajamie s solution and wrapped it up into a slightly more convenient script wrapper    I added an option to start from an offset before the end of the file  so you can use the tail-like functionality of reading a certain amount from the end of the file  Note the offset is in bytes  not lines    There s also an option to continue waiting for more content    Examples  assuming you save this as TailFile ps1      TailFile ps1 -File   path to myfile log -InitialOffset 1000000   TailFile ps1 -File   path to myfile log -InitialOffset 1000000 -Follow  true   TailFile ps1 -File   path to myfile log -Follow  true   And here is the script itself     param        Parameter Mandatory  true HelpMessage  Enter the path to a file to tail    string  File            Parameter Mandatory  true HelpMessage  Enter the number of bytes from the end of the file    int  InitialOffset   10248       Parameter Mandatory  false HelpMessage  Continuing monitoring the file for new additions     boolean  Follow    false     ci   get-childitem  File  fullName    ci FullName   reader   new-object System IO StreamReader New-Object IO FileStream  fullName   System IO FileMode   Open   System IO FileAccess   Read   IO FileShare   ReadWrite    start at the end of the file  lastMaxOffset    reader BaseStream Length -  InitialOffset  while   true         if the file size has not changed  idle     if   reader BaseStream Length -ge  lastMaxOffset             seek to the last max offset          reader BaseStream Seek  lastMaxOffset   System IO SeekOrigin   Begin    out-null           read out of the file until the EOF          line              while    line    reader ReadLine    -ne  null                write-output  line                     update the last max offset          lastMaxOffset    reader BaseStream Position            if  Follow           Start-Sleep -m 100       else           break

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There have been many valid answers  however  none of them has the same syntax as tail in linux  The following function can be stored in your  Home Documents PowerShell Microsoft PowerShell profile ps1 for persistency  see powershell profiles documentation for more details    This allows you to call     tail server log tail -n 5 server log tail -f server log tail -Follow -Lines 5 -Path server log   which comes quite close to the linux syntax   function tail    lt        SYNOPSIS         Get the last n lines of a text file       PARAMETER Follow         output appended data as the file grows      PARAMETER Lines         output the last N lines  default  10       PARAMETER Path         path to the text file      INPUTS         System Int         IO FileInfo      OUTPUTS         System String      EXAMPLE         PS gt  tail c  server log      EXAMPLE         PS gt  tail -f -n 20 c  server log   gt       CmdletBinding         OutputType  System String        Param           Alias  f             parameter Mandatory  false            switch  Follow            Alias  n             parameter Mandatory  false            Int  Lines   10            parameter Mandatory  true  Position 5            ValidateNotNullOrEmpty             IO FileInfo  Path           if   Follow                Get-Content -Path  Path -Tail  Lines -Wait           else               Get-Content -Path  Path -Tail  Lines

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As of PowerShell version 3 0  the Get-Content cmdlet has a -Tail parameter that should help  See the technet library online help for Get-Content

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PowerShell Community Extensions  PSCX  provides the Get-FileTail cmdlet  It looks like a suitable solution for the task  Note  I did not try it with extremely large files but the description says it efficiently tails the contents and it is designed for large log files   NAME     Get-FileTail  SYNOPSIS     PSCX Cmdlet  Tails the contents of a file - optionally waiting on new content   SYNTAX     Get-FileTail  -Path   lt String   gt   -Count  lt Int32 gt    -Encoding  lt EncodingParameter gt    -LineTerminator  lt String gt    -Wait    lt CommonParameters gt        Get-FileTail  -LiteralPath   lt String   gt   -Count  lt Int32 gt    -Encoding  lt EncodingParameter gt    -LineTerminator  lt String gt    -Wait    lt CommonParameters gt    DESCRIPTION     This implentation efficiently tails the cotents of a file by reading lines from the end rather then processing the entire file  This behavior is crucial for ef     ficiently tailing large log files and large log files over a network   You can also specify the Wait parameter to have the cmdlet wait and display new content     as it is written to the file   Use Ctrl C to break out of the wait loop   Note that if an encoding is not specified  the cmdlet will attempt to auto-detect the      encoding by reading the first character from the file  If no character haven t been written to the file yet  the cmdlet will default to using Unicode encoding       You can override this behavior by explicitly specifying the encoding via the Encoding parameter

User · Answer

Using Powershell V2 and below  get-content reads the entire file  so it was of no use to me   The following code works for what I needed  though there are likely some issues with character encodings   This is effectively tail -f  but it could be easily modified to get the last x bytes  or last x lines if you want to search backwards for line breaks      filename     wherever your file is txt   reader   new-object System IO StreamReader New-Object IO FileStream  filename   System IO FileMode   Open   System IO FileAccess   Read   IO FileShare   ReadWrite    start at the end of the file  lastMaxOffset    reader BaseStream Length  while   true        Start-Sleep -m 100       if the file size has not changed  idle     if   reader BaseStream Length -eq  lastMaxOffset            continue              seek to the last max offset      reader BaseStream Seek  lastMaxOffset   System IO SeekOrigin   Begin    out-null       read out of the file until the EOF      line          while    line    reader ReadLine    -ne  null            write-output  line             update the last max offset      lastMaxOffset    reader BaseStream Position     I found most of the code to do this here

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I used some of the answers given here but just a heads up that   Get-Content -Path Yourfile log -Tail 30 -Wait    will chew up memory after awhile  A colleague left such a  tail  up over the last day and it went up to 800 MB   I don t know if Unix tail behaves the same way  but I doubt it    So it s fine to use for short term applications  but be careful with it

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