<#*,:&cls
@echo off
cd /d "%~dp0"
powershell -NoProfile -ExecutionPolicy RemoteSigned -Command ". ([ScriptBlock]::Create((Get-Content -LiteralPath \"%~0\" -ReadCount 0 | Out-String ))) "
pause
exit /b
#>
# 功能:删除文件的最后N行
# 大文件
$file = "largeFile.txt"
# 最后N行
$lastN = 7
# 换行分割符
$charDelims = 13

try {
  $stream1 = New-Object System.IO.FileStream -ArgumentList @($file, [System.IO.FileMode]::Open, [System.IO.FileAccess]::ReadWrite, [System.IO.FileShare]::None)
  $pos = $stream1.Seek(0, [System.IO.SeekOrigin]::End)
  $ctrLines = 0
  while ($ctrLines -lt $lastN -and $pos -gt 0) {
    $pos = $stream1.Seek(-1, [System.IO.SeekOrigin]::Current)
    $byte = $stream1.ReadByte()
    if ($byte -eq $charDelims) {
      $ctrLines++
    }
    $pos = $stream1.Seek(-1, [System.IO.SeekOrigin]::Current)
  }
  $stream1.SetLength($pos)
} catch {
  $_ | Write-Host -ForegroundColor Red
} finally {
  if ($stream1) {
    $stream1.Dispose()
  }
}
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#&@cls&powershell "gc %~0|out-string|iex"&pause&exit
$file="aa.txt"
$txt=gc $file -readcount 0
$txt7=$txt[0..($txt.length-1-7)]
sc -value $txt7 "new-$file"
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