WEBVTT 00:01.070 --> 00:08.900 To get the most from your Linux system, you need to understand environment variables and be adept adept 00:08.900 --> 00:13.430 at managing them for optimal performance, convenience and even stealth. 00:13.940 --> 00:19.730 So among the areas that the Linux newcomers find problematic, however, managing the user environment 00:19.730 --> 00:23.060 variables might be the most difficult to master. 00:23.600 --> 00:25.940 So technically, there are two types of variables. 00:26.600 --> 00:29.960 The first is shell, and the second is environment. 00:30.800 --> 00:37.010 So environment variables are system wide variables built into your system and interface that control 00:37.010 --> 00:44.840 the way your system looks, acts and feels the to the user and they are inherited by end charge shills 00:44.840 --> 00:45.710 or processors. 00:46.730 --> 00:54.500 Social variables, on the other hand, are typically listed listed in lowercase and are only valid in 00:54.500 --> 00:55.220 their shell. 00:55.250 --> 00:56.480 They are set in. 00:57.140 --> 01:04.130 So to avoid over explanation, I just, uh, cover some of the most basic and useful skills for environment 01:04.130 --> 01:10.460 and shell variables in this lectures and don't go too deeply into the differences between them. 01:11.240 --> 01:15.890 So variables are simple strings in key value pairs. 01:16.460 --> 01:28.100 So again, or generally, each pair will look like this, for example, key and value key here and add 01:28.100 --> 01:28.940 value here. 01:29.750 --> 01:30.200 So. 01:32.520 --> 01:42.750 In cases where there are multiple values, they will look like this is a value one value to and value 01:42.760 --> 01:44.610 three and vice versa here. 01:45.450 --> 01:53.790 So as with most things in Linux, if there are spaces in the value, it needs to be contained in a quotation 01:53.790 --> 01:54.870 marks here. 01:56.710 --> 01:57.410 Like that? 01:58.800 --> 02:00.290 While the fourth. 02:02.720 --> 02:03.140 So. 02:08.140 --> 02:12.640 So in in your environment, in your shell is your best shell. 02:12.910 --> 02:19.540 So each user, including ruled, has a different set of environment variables that determine how the 02:19.540 --> 02:21.280 system looks, acts and. 02:22.060 --> 02:28.570 So you can change the values for these variables to make your system work more efficiently. 02:28.810 --> 02:33.970 Tailor your work environment to best meet your individual needs and potentially cover your tracks if 02:33.970 --> 02:34.660 you need to. 02:35.740 --> 02:42.100 So leaving and modifying environment variables so you can be while your default environment variables 02:42.100 --> 02:49.060 by entering any V into your terminal from any directory like so here. 02:49.960 --> 02:54.010 So as you can see, there is a light environment variables here. 02:57.660 --> 03:03.660 So environment variables are always upper case, as you can see here. 03:05.190 --> 03:12.570 So, including shell variables, local variables and show functions such as any user defined variables 03:12.570 --> 03:20.050 and command aliases, some use a set common this command will list all environment variables. 03:20.520 --> 03:28.410 Um, on environment variables unique to your system, which is the most cases will give you an output 03:28.410 --> 03:33.660 so long you won't be able to view it, uh, on a single screen here. 03:34.230 --> 03:35.430 So you can see here. 03:36.360 --> 03:40.410 We have so many environment variables here. 03:43.680 --> 03:51.660 As you can see here, we can see, because it's so many here, so, uh, we can do like that, sit here. 03:52.620 --> 03:53.070 Said. 03:54.260 --> 03:55.880 And more here. 03:57.220 --> 04:00.100 Now we can see like that by pressing enter. 04:00.430 --> 04:02.040 We can see a sequential. 04:02.400 --> 04:10.990 So let's see more more and, uh, press in one time control and save or exit or quit here. 04:11.980 --> 04:17.740 So now the last three of us here, as you can see here, feel, uh, will fill up on a screen line by 04:17.740 --> 04:18.880 line and then stop. 04:19.330 --> 04:26.940 Uh, when you press enter like that, uh, or space or, uh, spin in space and you will see more here. 04:28.160 --> 04:36.020 Uh, so, uh, taking you to the next variable so you can scroll through pressing or holding, enter 04:36.020 --> 04:36.560 like that. 04:37.190 --> 04:37.580 So. 04:39.490 --> 04:46.990 As you might recall, from previous chapters and elections, whenever you you use, the more common 04:46.990 --> 04:59.380 for output you can enter key it to or exit and return command to like that or control plus easier. 05:00.190 --> 05:03.490 So filtering for particular variables? 05:03.910 --> 05:06.160 Let me, uh, see here. 05:06.170 --> 05:14.440 So, uh, I'll talk to you using sent, uh, with more gifts, more, uh, manageable results than working 05:14.440 --> 05:20.950 through the whole chunk of variable names you get with this sit along like that. 05:22.030 --> 05:23.020 Uh, so. 05:24.740 --> 05:28.580 It can still be a rather tedious if you are looking for a particular variable. 05:28.880 --> 05:35.540 Instead, you can use the filtering command grant, um to find your variable of interest. 05:35.960 --> 05:39.350 So let's use the variable his size as an example. 05:39.770 --> 05:46.070 So this variable contains his size on this variable contains the maximum number of comments you were. 05:46.070 --> 05:48.470 Common history of a file was stored. 05:49.190 --> 05:58.310 So his size is the maximum and number of commands your command history file will start to his commands 05:58.550 --> 06:06.070 or any was previously typed into your command prompt in the session and can be recalled with your up 06:06.080 --> 06:10.760 here, up and down, uh, keywords like that. 06:13.440 --> 06:19.710 So you're not at his size, doesn't store the comments themselves, just a number of them that can be 06:19.720 --> 06:29.580 stored so popular, sit here said, Oh crap, actually cramp his size. 06:29.970 --> 06:30.300 Yeah. 06:30.980 --> 06:33.870 Well, as you can see, his size is 1000. 06:34.200 --> 06:39.840 As you can see, the common finds the variable, his size, and this place is its value. 06:40.230 --> 06:45.570 The default value of this variable is probably set to one thousand here, as you can see on your system, 06:45.570 --> 06:45.900 too. 06:46.230 --> 06:52.080 So this indicates the terminal this storage would last 1000 commands by default.