WEBVTT 00:03.060 --> 00:08.250 Windows PowerShell uses the tri catch finally construct to implement error handling. 00:09.090 --> 00:13.440 Note Windows PowerShell also uses the trap construct for error handling. 00:14.250 --> 00:20.340 This construct was introduced in Windows PowerShell 1.0 and is more difficult and less flexible than 00:20.340 --> 00:21.240 try catch. 00:21.270 --> 00:25.560 Finally, you should use try catch finally in new scripts. 00:26.460 --> 00:30.300 As the name implies, the construct consists of up to three sections. 00:31.200 --> 00:34.080 The try section contains commands that may have an error. 00:35.010 --> 00:40.410 These commands must have their error actions set to stop, or the error action preference variable must 00:40.410 --> 00:41.310 be set to stop. 00:42.180 --> 00:43.590 This section is required. 00:44.460 --> 00:48.570 The catch section is optional and will run if an error happens in the try section. 00:49.410 --> 00:54.630 The final section is optional and will run regardless of whether an error happens in the try section 00:55.470 --> 00:56.340 if it is used. 00:56.370 --> 00:58.080 Finally must come after catch. 00:58.980 --> 01:00.660 You do not have to use both catch. 01:00.660 --> 01:04.320 And finally, however, you must use at least one of them. 01:05.160 --> 01:10.230 You can have multiple catch sections configured so that each section handles a different kind of error. 01:11.130 --> 01:15.420 For more information about how to do this, read the above underscore try underscore. 01:15.420 --> 01:16.200 Catch underscore. 01:16.200 --> 01:18.420 Finally help file in Windows PowerShell. 01:19.290 --> 01:20.400 Here is an example. 01:21.250 --> 01:28.660 Try get WMI object class win32 underscore service computer name dollars name error action. 01:28.660 --> 01:29.080 Stop. 01:29.920 --> 01:30.400 Catch. 01:31.260 --> 01:31.590 Right. 01:31.590 --> 01:33.600 Verbose error connecting to dollar name. 01:34.440 --> 01:37.920 Note The final section of this construct is rarely used. 01:38.820 --> 01:42.720 That is why the construct is known as tri catch instead of tri catch. 01:42.750 --> 01:48.780 Finally, remember that setting error action to stop will turn any error into a terminating error. 01:49.680 --> 01:52.320 That means the command will not continue to process. 01:53.280 --> 01:58.230 For this reason, you will usually write your script so that the command is processing only one thing 01:58.230 --> 01:58.830 at a time. 01:59.610 --> 02:04.140 In this example, that means the name would contain only one computer name at a time. 02:04.410 --> 02:08.190 So if one computer name fails, the command is not skipping anything.