1 00:00:01,640 --> 00:00:05,220 The environment provider has numerous built‑in variables that stores 2 00:00:05,220 --> 00:00:08,640 information about the operating system environment. 3 00:00:08,640 --> 00:00:13,840 These information are accessed by OS, scripts, and programs. 4 00:00:13,840 --> 00:00:17,200 These variables provide information like the Windows directory, 5 00:00:17,200 --> 00:00:20,940 OS installation path, temporary directory path, 6 00:00:20,940 --> 00:00:26,340 user's OneDrive, and many such details, which we will look further in demo. 7 00:00:26,340 --> 00:00:29,640 Almost all these variables are self‑explanatory, 8 00:00:29,640 --> 00:00:32,670 and we won't feel the need to emphasize much on each 9 00:00:32,670 --> 00:00:34,840 and every environment variable. 10 00:00:34,840 --> 00:00:40,240 We'll try to cover most of them and especially the ones that are used widely. 11 00:00:40,240 --> 00:00:44,240 So now, we will quickly jump into our demo environment. 12 00:00:44,240 --> 00:00:49,040 In this demo, we will look into the significance of environment variables. 13 00:00:49,040 --> 00:00:53,920 We will then see how to extract values out of these environment variables. 14 00:00:53,920 --> 00:00:57,540 To list all the environment variables. 15 00:00:57,540 --> 00:01:01,590 I will run Get‑ChildItem and enter env:\ drive. 16 00:01:01,590 --> 00:01:06,140 On the left side, we have the list of environment variables, 17 00:01:06,140 --> 00:01:10,840 and on the right side, we have the values that are stored in those variables. 18 00:01:10,840 --> 00:01:16,740 The first one is ALLUSERSPROFILE that points to c:\ProgramData folder. 19 00:01:16,740 --> 00:01:21,340 The second one is APPDATA that points to Users, Roaming folder. 20 00:01:21,340 --> 00:01:25,940 So, if in a script, I want to change my directory to this path, 21 00:01:25,940 --> 00:01:29,570 I can easily mention ALLUSERSPROFILE variable instead of 22 00:01:29,570 --> 00:01:32,340 typing the entire Roaming folder path. 23 00:01:32,340 --> 00:01:35,510 We then have ProgramFiles variable that provides 24 00:01:35,510 --> 00:01:38,440 details about ProgramFiles folders. 25 00:01:38,440 --> 00:01:42,670 Next is one of the widely used variable COMPUTERNAME. That 26 00:01:42,670 --> 00:01:45,240 provides the hostname of the system. 27 00:01:45,240 --> 00:01:49,900 Imagine you are extracting some data from hundreds of computers and 28 00:01:49,900 --> 00:01:52,940 exporting their data in their respective text file. 29 00:01:52,940 --> 00:01:54,950 If you bring all those files together, 30 00:01:54,950 --> 00:01:57,540 how will you differentiate between each file? 31 00:01:57,540 --> 00:02:02,040 The solution to this is that you can use COMPUTERNAME variable in the script, 32 00:02:02,040 --> 00:02:06,940 extract the hostname, and save the text file with the hostname in it. 33 00:02:06,940 --> 00:02:09,540 This would look something like this. 34 00:02:09,540 --> 00:02:12,320 The ComSpec variable specifies and points to the 35 00:02:12,320 --> 00:02:14,750 command‑line interpreter of the OS. 36 00:02:14,750 --> 00:02:19,010 DriverData variable gives information about DriverData folder path. 37 00:02:19,010 --> 00:02:21,170 The HOMEDRIVE, HOMEPATH, 38 00:02:21,170 --> 00:02:25,490 and LOCALAPPDATA variables points to the Users home drive, 39 00:02:25,490 --> 00:02:29,330 Users home directory, and AppData\Local folder. 40 00:02:29,330 --> 00:02:33,420 We then have LOGONSERVER variable that basically tells us which 41 00:02:33,420 --> 00:02:36,320 domain controller the system has logged on to. 42 00:02:36,320 --> 00:02:40,640 In case of non‑domain joined machine or local user login, 43 00:02:40,640 --> 00:02:43,440 local computers name will be shown here. 44 00:02:43,440 --> 00:02:47,640 We then have some variables that gives information about processor. 45 00:02:47,640 --> 00:02:52,350 The OneDrive variable specifies the path to Users OneDrive location. 46 00:02:52,350 --> 00:02:55,520 The Path variable specifies group of directories where 47 00:02:55,520 --> 00:02:59,640 executable programs are located. 48 00:02:59,640 --> 00:03:04,740 PSModulePath specifies the paths where PowerShell modules resides. 49 00:03:04,740 --> 00:03:07,310 Then we have the variable for PUBLIC folder, 50 00:03:07,310 --> 00:03:11,640 SystemDrive, SystemRoot, and Temp folders. 51 00:03:11,640 --> 00:03:15,430 We then have variables that provides information about Users domain, 52 00:03:15,430 --> 00:03:19,040 Users account, and Users profile. 53 00:03:19,040 --> 00:03:19,600 Lastly, 54 00:03:19,600 --> 00:03:25,560 we have windir variable that specifies the drive where Windows is installed. 55 00:03:25,560 --> 00:03:29,400 I'll now show you how to extract values from these variables. 56 00:03:29,400 --> 00:03:32,670 The syntax to use environment variable is to start with 57 00:03:32,670 --> 00:03:37,180 dollar sign and then and enter env:colon, 58 00:03:37,180 --> 00:03:42,620 followed by variable name, First, I'll take an example of COMPUTERNAME variable. 59 00:03:42,620 --> 00:03:46,840 When I hit Enter, it will return COMPUTERNAME. 60 00:03:46,840 --> 00:03:50,410 The example which we saw earlier where COMPUTERNAME was served 61 00:03:50,410 --> 00:03:53,490 in the file can be achieved by doing this. 62 00:03:53,490 --> 00:03:59,240 In the FilePath parameter of Out‑File command, once you enter the FileName, 63 00:03:59,240 --> 00:04:01,940 you can append the COMPUTERNAME. 64 00:04:01,940 --> 00:04:04,940 This will extract hostname from COMPUTERNAME environment 65 00:04:04,940 --> 00:04:08,440 variable and append it to the FileName. 66 00:04:08,440 --> 00:04:12,480 I'll now show you the file that is created. Here, 67 00:04:12,480 --> 00:04:16,330 it has the FileName, followed by the hostname. 68 00:04:16,330 --> 00:04:17,240 Similarly, 69 00:04:17,240 --> 00:04:24,040 I can use USERPROFILE variable to save the file directly in the Users directory. 70 00:04:24,040 --> 00:04:28,320 I can fetch my Log‑on server using LOGONSERVER variable. I 71 00:04:28,320 --> 00:04:31,980 can also get the details of my Active Directory domain using 72 00:04:31,980 --> 00:04:35,110 USERDNSDOMAIN variable; likewise, 73 00:04:35,110 --> 00:04:43,000 you can make use of these env variables in a number of places, and that totally depends on your script requirement.