To indicate the current session, specify WTS_CURRENT_SESSION. To retrieve the identifiers of all sessions on a specified terminal server, use the WTSEnumerateSessions function.

static extern int WTSEnumerateSessions(

static extern void WTSEnumerateSessions(

    WTSEnumerateSessions(hServer,0,1,ppSessionInfo,pCount);

public static extern int WTSEnumerateSessions(

    static extern Int32 WTSEnumerateSessions(

        Int32 retval = WTSEnumerateSessions(server, 0, 1, ref ppSessionInfo, ref count);

public static extern int WTSEnumerateSessions(

$wtsenum = add-type -MemberDefinition $wtsenumsig -Name PSWTSEnumerateSessions -Namespace GetLoggedOnUsers -PassThru

[long]$retval = $wtsenum::WTSEnumerateSessions($server,0,1,[ref]$ppSessionInfo,[ref]$count)

    EntryPoint:="WTSEnumerateSessions", _

    Private Shared Function WTSEnumerateSessions( _

    EntryPoint:="WTSEnumerateSessions", _

    Private Shared Function WTSEnumerateSessions( _

        FRetVal = WTSEnumerateSessions(ptrOpenedServer, 0, 1, ppSessionInfo, Count)