#include <StringConstants.au3> ; to declare the Constants of StringRegExp
#include <Array.au3> ; UDF needed for _ArrayDisplay and _ArrayConcatenate
Local $sRegex = "(?m)(.*?_){3}(?<container>[^_]+)"
Local $sString = "k8s_jenkins_jenkins-16-mrlz4_tau-ops_eb099c1d-6d70-11ea-8ba8-001a4a160104_0" & @CRLF & _
"k8s_datadog-agent_datadog-agent-t4dlc_clusteradmin_dd5f238b-6a16-11ea-8ef9-566f4e1c0167_351" & @CRLF & _
"k8s_core-order-service_core-order-service-deployment-1-t9b29_fltc-ods-uit_b10cf94d-64b1-11ea-8ef9-566f4e1c0167_3513"
Local $aArray = StringRegExp($sString, $sRegex, $STR_REGEXPARRAYGLOBALFULLMATCH)
Local $aFullArray[0]
For $i = 0 To UBound($aArray) -1
_ArrayConcatenate($aFullArray, $aArray[$i])
Next
$aArray = $aFullArray
; Present the entire match result
_ArrayDisplay($aArray, "Result")
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for AutoIt, please visit: https://www.autoitscript.com/autoit3/docs/functions/StringRegExp.htm