WEBVTT 1 00:00:00.000 --> 00:00:01.380 In this lesson, 2 00:00:01.380 --> 00:00:03.690 we will learn about PowerShell. 3 00:00:03.690 --> 00:00:06.660 PowerShell is a powerful scripting language 4 00:00:06.660 --> 00:00:10.800 and command line shell designed for automating tasks 5 00:00:10.800 --> 00:00:14.970 and managing configurations in Windows environments. 6 00:00:14.970 --> 00:00:19.530 In PowerShell, data structures such as variables, arrays, 7 00:00:19.530 --> 00:00:24.420 hash tables, strings, and objects are used to store 8 00:00:24.420 --> 00:00:26.730 and manipulate complex data, 9 00:00:26.730 --> 00:00:29.880 making it easy to handle system information 10 00:00:29.880 --> 00:00:32.190 and configuration details. 11 00:00:32.190 --> 00:00:35.310 Script control structures, including loops 12 00:00:35.310 --> 00:00:38.430 like for, foreach, and while, 13 00:00:38.430 --> 00:00:42.330 and conditional statements like, if and switch, 14 00:00:42.330 --> 00:00:45.990 allows scripts to execute repetitive tasks 15 00:00:45.990 --> 00:00:49.860 and make decisions based on specific conditions. 16 00:00:49.860 --> 00:00:53.490 Let's learn more about PowerShell data structures 17 00:00:53.490 --> 00:00:55.560 and control structures. 18 00:00:55.560 --> 00:00:58.860 First, we have PowerShell data structures. 19 00:00:58.860 --> 00:01:02.550 In PowerShell, data structures play a key role 20 00:01:02.550 --> 00:01:05.550 in managing and organizing data, 21 00:01:05.550 --> 00:01:10.550 variables, arrays, hash tables and objects are all tools 22 00:01:10.950 --> 00:01:14.340 that make it easy to store and manipulate data 23 00:01:14.340 --> 00:01:16.410 with PowerShell scripts. 24 00:01:16.410 --> 00:01:19.620 For example, in a PowerShell script, 25 00:01:19.620 --> 00:01:23.400 a variable could store something like a log file path 26 00:01:23.400 --> 00:01:27.030 or even specific log on failure details. 27 00:01:27.030 --> 00:01:29.610 Overall, PowerShell allows us 28 00:01:29.610 --> 00:01:33.043 to manage data efficiently through cmdlets. 29 00:01:33.043 --> 00:01:38.043 A cmdlet is a lightweight verb-noun formatted command 30 00:01:38.070 --> 00:01:39.720 that performs an action, 31 00:01:39.720 --> 00:01:44.190 and typically returns a microsoft.net object. 32 00:01:44.190 --> 00:01:47.970 Now let's take a look at some PowerShell code. 33 00:01:47.970 --> 00:01:52.890 In this case, the output of the Get-EventLog cmdlet 34 00:01:52.890 --> 00:01:57.540 is a collection of objects that represent log entries, 35 00:01:57.540 --> 00:01:59.970 with each one containing properties 36 00:01:59.970 --> 00:02:02.610 like timewritten and message. 37 00:02:02.610 --> 00:02:05.850 These are microsoft.net objects, 38 00:02:05.850 --> 00:02:09.030 and they act as a powerful data structure 39 00:02:09.030 --> 00:02:12.330 allowing us to easily access and process 40 00:02:12.330 --> 00:02:14.700 specific pieces of data. 41 00:02:14.700 --> 00:02:17.460 In this snippet, PowerShell is retrieving 42 00:02:17.460 --> 00:02:22.140 the five most recent log entries from the security log 43 00:02:22.140 --> 00:02:26.580 that match the instance ID of 4625, 44 00:02:26.580 --> 00:02:30.120 which corresponds to log-on failures. 45 00:02:30.120 --> 00:02:32.940 The data is output as objects 46 00:02:32.940 --> 00:02:35.700 and sent through the pipe operator, 47 00:02:35.700 --> 00:02:38.910 which is represented by that vertical line. 48 00:02:38.910 --> 00:02:42.540 A pipe operator takes the output from the command 49 00:02:42.540 --> 00:02:45.510 on its left and sends it as input 50 00:02:45.510 --> 00:02:48.180 to the command on its right. 51 00:02:48.180 --> 00:02:51.780 The properties timewritten and messages 52 00:02:51.780 --> 00:02:54.180 are selected from the log entries 53 00:02:54.180 --> 00:02:57.090 on the left side of the pipe operator, 54 00:02:57.090 --> 00:03:02.090 and they are passed as input into the out file cmdlet, 55 00:03:02.310 --> 00:03:07.310 which writes this information to a file called log-fail.txt. 56 00:03:08.580 --> 00:03:12.960 This demonstrates how PowerShell handles complex data 57 00:03:12.960 --> 00:03:17.340 by turning log entries into objects that can be filtered, 58 00:03:17.340 --> 00:03:21.000 manipulated, and stored with minimal effort. 59 00:03:21.000 --> 00:03:24.600 PowerShell also uses other data structures, 60 00:03:24.600 --> 00:03:28.440 such as arrays, to store lists of items. 61 00:03:28.440 --> 00:03:31.320 For example, an array could be used 62 00:03:31.320 --> 00:03:33.690 to store multiple log entries 63 00:03:33.690 --> 00:03:37.320 or a list of user accounts for auditing. 64 00:03:37.320 --> 00:03:39.780 Arrays can be looped through easily, 65 00:03:39.780 --> 00:03:43.560 as we'll see when discussing control structures, 66 00:03:43.560 --> 00:03:45.990 making them a flexible tool 67 00:03:45.990 --> 00:03:48.840 for managing collections of data. 68 00:03:48.840 --> 00:03:53.460 Overall, Powershell's built-in support for handling objects 69 00:03:53.460 --> 00:03:57.780 and structured data makes it particularly well-suited 70 00:03:57.780 --> 00:04:00.900 for system administration tasks. 71 00:04:00.900 --> 00:04:04.980 Second, we have PowerShell control structures. 72 00:04:04.980 --> 00:04:08.610 Control structures in PowerShell enables scripts 73 00:04:08.610 --> 00:04:12.060 to handle repetitive tasks, make decisions, 74 00:04:12.060 --> 00:04:15.900 and respond dynamically to different conditions. 75 00:04:15.900 --> 00:04:20.670 These structures allow for efficient automation of tasks, 76 00:04:20.670 --> 00:04:23.280 such as gathering system data, 77 00:04:23.280 --> 00:04:26.460 iterating over collections of information, 78 00:04:26.460 --> 00:04:30.600 and performing actions based on specific criteria. 79 00:04:30.600 --> 00:04:34.500 For example, when using the right host cmdlet, 80 00:04:34.500 --> 00:04:37.080 a message can be printed to the screen 81 00:04:37.080 --> 00:04:41.310 to inform the user about the progress of the script. 82 00:04:41.310 --> 00:04:45.900 This feedback is used in scripts that may take time to run, 83 00:04:45.900 --> 00:04:50.490 or involve multiple steps, ensuring the user understands 84 00:04:50.490 --> 00:04:53.640 what is being executed as it occurs. 85 00:04:53.640 --> 00:04:57.840 Next, the if and else control structures are used 86 00:04:57.840 --> 00:05:00.960 for decision making, allowing a script 87 00:05:00.960 --> 00:05:04.440 to take different actions based on whether a condition 88 00:05:04.440 --> 00:05:06.360 is true or false. 89 00:05:06.360 --> 00:05:09.180 For instance, a script might check 90 00:05:09.180 --> 00:05:11.520 whether a user is an administrator, 91 00:05:11.520 --> 00:05:14.040 and display a message accordingly. 92 00:05:14.040 --> 00:05:19.040 Additionally, loops like for and foreach make it possible 93 00:05:19.110 --> 00:05:22.770 to repeat tasks over a series of elements, 94 00:05:22.770 --> 00:05:26.760 such as a long list of log entries or users. 95 00:05:26.760 --> 00:05:28.980 The loops work hand in hand 96 00:05:28.980 --> 00:05:31.740 with cmdlets like a Get-EventLog, 97 00:05:31.740 --> 00:05:34.680 allowing the script to dynamically retrieve 98 00:05:34.680 --> 00:05:38.430 and process system data, such as checking for 99 00:05:38.430 --> 00:05:42.330 log-on failures or specific event IDs. 100 00:05:42.330 --> 00:05:46.650 Next, using loops to iterate over collections of data 101 00:05:46.650 --> 00:05:50.280 allows PowerShell scripts to automate tasks 102 00:05:50.280 --> 00:05:54.480 that would otherwise be time-consuming or prone to error 103 00:05:54.480 --> 00:05:55.980 if done manually. 104 00:05:55.980 --> 00:05:59.280 For example, a foreach loop can go through 105 00:05:59.280 --> 00:06:01.950 all the log entries in a collection, 106 00:06:01.950 --> 00:06:04.980 checking each one for a specific condition, 107 00:06:04.980 --> 00:06:07.110 like being a failed log-on. 108 00:06:07.110 --> 00:06:09.180 If a failure is found, 109 00:06:09.180 --> 00:06:11.790 the script can take appropriate action, 110 00:06:11.790 --> 00:06:14.880 such as printing out a message to the screen, 111 00:06:14.880 --> 00:06:18.960 or saving those details to a file for further review. 112 00:06:18.960 --> 00:06:21.960 This automated decision-making process 113 00:06:21.960 --> 00:06:24.750 makes PowerShell scripts highly flexible 114 00:06:24.750 --> 00:06:27.300 and powerful for system management. 115 00:06:27.300 --> 00:06:29.880 Finally, we have a switch statement. 116 00:06:29.880 --> 00:06:33.600 This is another important control structure in PowerShell. 117 00:06:33.600 --> 00:06:36.090 It provides a more efficient way 118 00:06:36.090 --> 00:06:38.130 to handle multiple conditions 119 00:06:38.130 --> 00:06:41.340 compared to using multiple if statements. 120 00:06:41.340 --> 00:06:45.090 When a variable can have several possible values, 121 00:06:45.090 --> 00:06:47.490 a switch statement allows the script 122 00:06:47.490 --> 00:06:50.850 to match the variable against each value, 123 00:06:50.850 --> 00:06:54.450 and then execute the appropriate block of code. 124 00:06:54.450 --> 00:06:57.540 By combining conditional statements, loops, 125 00:06:57.540 --> 00:07:01.200 and cmdlets, PowerShell control structures provide 126 00:07:01.200 --> 00:07:04.590 the tools needed to automate and simplify 127 00:07:04.590 --> 00:07:06.930 complex system tasks. 128 00:07:06.930 --> 00:07:09.420 Now let's take a look at a script, 129 00:07:09.420 --> 00:07:11.640 and I know this is a long one. 130 00:07:11.640 --> 00:07:15.900 The script on the screen uses PowerShell control structures 131 00:07:15.900 --> 00:07:20.790 like if, else, for, foreach, and switch 132 00:07:20.790 --> 00:07:25.230 to automate tasks, handle data, and make decisions 133 00:07:25.230 --> 00:07:27.540 based on different conditions. 134 00:07:27.540 --> 00:07:30.750 Let's take a look at each control structure. 135 00:07:30.750 --> 00:07:34.320 The script first checks if the logged in user 136 00:07:34.320 --> 00:07:38.280 is an administrator using the if else statement. 137 00:07:38.280 --> 00:07:42.450 If the user is admin, a welcome message is printed. 138 00:07:42.450 --> 00:07:46.740 Otherwise it displays an access denied message. 139 00:07:46.740 --> 00:07:49.020 Next, a for loop is used 140 00:07:49.020 --> 00:07:51.690 to iterate through a series of numbers, 141 00:07:51.690 --> 00:07:55.620 printing the number of the iteration each time. 142 00:07:55.620 --> 00:08:00.420 This is a simple but repetitive task often used in scripts. 143 00:08:00.420 --> 00:08:04.260 Next, in the script, a foreach loop iterates 144 00:08:04.260 --> 00:08:08.250 through a list of users, printing out each user's name 145 00:08:08.250 --> 00:08:10.080 as it processes them. 146 00:08:10.080 --> 00:08:13.530 This is useful when working with collections, like arrays 147 00:08:13.530 --> 00:08:15.720 or lists in PowerShell. 148 00:08:15.720 --> 00:08:17.970 And finally, a switch statement 149 00:08:17.970 --> 00:08:20.910 checks the value of the role variable, 150 00:08:20.910 --> 00:08:24.690 and performs actions based on the match to value. 151 00:08:24.690 --> 00:08:27.780 For example, if the role is admin, 152 00:08:27.780 --> 00:08:30.540 the user gets admin privileges. 153 00:08:30.540 --> 00:08:35.280 Or if the role is user or guest, appropriate messages 154 00:08:35.280 --> 00:08:37.530 are printed out to the screen. 155 00:08:37.530 --> 00:08:40.710 As you can see, PowerShell control structures, 156 00:08:40.710 --> 00:08:45.710 like if, else, for, foreach, and switch provide tools 157 00:08:46.080 --> 00:08:51.080 for automating complex tasks and handling data efficiently. 158 00:08:51.120 --> 00:08:53.580 By combining these control structures 159 00:08:53.580 --> 00:08:56.640 with cmdlets, scripts can make decisions, 160 00:08:56.640 --> 00:08:58.650 perform repetitive actions 161 00:08:58.650 --> 00:09:02.190 and respond dynamically to various conditions, 162 00:09:02.190 --> 00:09:06.330 making PowerShell highly effective for system management. 163 00:09:06.330 --> 00:09:11.330 So remember, PowerShell is a powerful scripting language 164 00:09:11.760 --> 00:09:16.320 designed for automating tasks and managing configurations 165 00:09:16.320 --> 00:09:18.390 in a Windows environment. 166 00:09:18.390 --> 00:09:22.650 It uses various data structures, such as variables, 167 00:09:22.650 --> 00:09:25.770 arrays, hash tables, and objects 168 00:09:25.770 --> 00:09:30.000 to efficiently store and manipulate complex data. 169 00:09:30.000 --> 00:09:34.530 Control structures like if, else, for, foreach, 170 00:09:34.530 --> 00:09:37.740 and switch enable PowerShell scripts 171 00:09:37.740 --> 00:09:39.990 to perform repetitive tasks 172 00:09:39.990 --> 00:09:44.010 and make decisions based on specific conditions. 173 00:09:44.010 --> 00:09:47.760 By combining these control structures with cmdlets, 174 00:09:47.760 --> 00:09:50.640 PowerShell scripts can dynamically retrieve, 175 00:09:50.640 --> 00:09:53.910 process, and act upon system data. 176 00:09:53.910 --> 00:09:58.110 This flexibility and functionality make PowerShell 177 00:09:58.110 --> 00:10:01.770 an effective tool for automating and managing 178 00:10:01.770 --> 00:10:04.503 complex system tasks.