结合计划任务每天从Symantec官网下载离线病毒库

#三种方法,由初级到高级

$numbers = 1..40 | Foreach {"{0:D3}" -f $_}
#将数字类型格式化并转换为字符串类型使用-f字符串操作符
ForEach ($number in $numbers) {
$Source = 'http://definitions.symantec.com/defs/' + ((Get-Date -Format yyyyMMdd) - 1) + '-' + $number + '-v5i32.exe'
$Destination = "F:\" + ((Get-Date -Format yyyyMMdd) - 1) + "-" + $number + ".exe"
Invoke-WebRequest -uri $Source -OutFile $Destination
}

$webreq = Invoke-WebRequest http://www.symantec.com/security_response/definitions/download/detail.jsp?gid=savce
$webreq.Content | Out-File C:\output.txt -Force
$txt = (Get-Content -Path C:\output.txt -TotalCount 924)[-1]
$src = $txt.Substring(59,59)
$des = "c:\" + $txt.Substring(96,22)
Invoke-WebRequest -uri $src -OutFile $des

$webreq = Invoke-WebRequest http://www.symantec.com/security_response/definitions/download/detail.jsp?gid=savce
$gc = $webreq.Content
$src = [regex]::Matches("$gc",'http://definitions.symantec.com/defs/.{0,20}\.exe') | Foreach-object {$_.value}        #正则表达式
$des = "c:\" + $src[0].substring(37,22)
Invoke-WebRequest -uri $src[0] -OutFile $des