你可以做到的

$myString = "C:\Users\testinguser\OneDrive - Company\Desktop\Hello\Jobs\Testing-Online\_vti_history\101376\Shared Documents\Global PKI\Legacy Stuff\Vehicle Credential Trackers\Tracker_JLN_records_USE.xlsx" -split "(\\_)"
Write-Output $myString[2]

输出：vti_history\101376\Shared Documents\Global PKI\Legacy Stuff\Vehicle Credential Trackers\Tracker_JLN_records_USE.xlsx

有几件事是错的。由于[2]的运算符优先级较高，您在$NULL上拆分，因为(‘_’)只有2个字符。括号是不必要的，但没有坏处，因为拆分不是一个函数。在'\_'上拆分会产生正则表达式解析错误，因此必须转义反斜杠。对'(\\_)'进行拆分，并将括号放在引号内，将在结果中包括分隔符。

$Path = 'C:\Users\testinguser\OneDrive - Company\Desktop\Hello\Jobs\Testing-Online\_vti_history\101376\Shared Documents\Global JLN\Legacy Stuff\Vehicle Credential Trackers\Tracker_JLN_records_USE.xlsx'

($Path -split '\\_')[1]

vti_history\101376\Shared Documents\Global JLN\Legacy Stuff\Vehicle Credential Trackers\Tracker_JLN_records_USE.xlsx

$Path -split '\_'

parsing "\_" - Unrecognized escape sequence \_.
At line:1 char:1
+ $Path -split '\_'
+ ~~~~~~~~~~~~~~~~~
    + CategoryInfo          : OperationStopped: (:) [], ArgumentException
    + FullyQualifiedErrorId : System.ArgumentException

$Path -split '(\\_)'

C:\Users\testinguser\OneDrive - Company\Desktop\Hello\Jobs\Testing-Online
\_
vti_history\101376\Shared Documents\Global JLN\Legacy Stuff\Vehicle Credential Trackers\Tracker_JLN_records_USE.xlsx

'\_'[2] -eq $null

True

在字符串数组是第一个参数(而不是字符数组)的情况下，您可以使用字符串拆分.Net函数重载之一，但它需要第二个参数。这样您就不必担心如何转义正则表达式字符。使用单个字符分隔符会更容易。

# string[] Split(string[] separator, System.StringSplitOptions options)

$path.split([string[]]'\_','None')

# $path.split((,'\_'),0)

C:\Users\testinguser\OneDrive - Company\Desktop\Hello\Jobs\Testing-Online
vti_history\101376\Shared Documents\Global JLN\Legacy Stuff\Vehicle Credential Trackers\Tracker_JLN_records_USE.xlsx

查看所有重载：

$path.split

OverloadDefinitions
-------------------
string[] Split(Params char[] separator)
string[] Split(char[] separator, int count)
string[] Split(char[] separator, System.StringSplitOptions options)
string[] Split(char[] separator, int count, System.StringSplitOptions options)
string[] Split(string[] separator, System.StringSplitOptions options)
string[] Split(string[] separator, int count, System.StringSplitOptions options)