按月将Windows日志导出至CSV文件

# 这个月的第一天
#..........................................到这里之前是取当年第一天
#(Get-Date 0).AddYears((Get-Date).Year - 1).AddMonths((Get-Date).Month - 2)
# 这个月的最后一天
#......................................................................到这里之前是次年第一天
#(Get-Date 0).AddYears((Get-Date).Year - 1).AddMonths((Get-Date).Month - 1).AddDays(-1)

$lognames = "Application","Security","System"
$lastmonthfirstday = (Get-Date 0).AddYears((Get-Date).Year - 1).AddMonths((Get-Date).Month - 2)
$lastmonthlastday = (Get-Date 0).AddYears((Get-Date).Year - 1).AddMonths((Get-Date).Month - 1).AddDays(-1)
foreach($logname in $lognames) {
    Get-EventLog -ComputerName $env:COMPUTERNAME -LogName $logname -After $lastmonthfirstday -Before $lastmonthlastday | Export-Csv -Path ("C:EventLog" + $lastmonthfirstday.Year + "_" + $lastmonthfirstday.Month + "_" + $env:COMPUTERNAME + "_" + $logname + ".CSV")
}