WEBVTT 00:00.900 --> 00:03.390 Changing variable values for a session. 00:03.930 --> 00:09.270 So now now let's see how the changing variables value as not adhered to. 00:09.270 --> 00:14.880 His side's variable contains the value of the number of commands to store in the history file. 00:15.390 --> 00:21.120 Sometimes you won't want your system to save past commands, perhaps because you don't want to leave 00:21.120 --> 00:25.560 any evidence of your activity on your own system or the target system. 00:25.890 --> 00:29.580 So in that case, you can set the his size variable to zero. 00:29.850 --> 00:35.670 So the system will install any of your past commands because this variable has a single value to change 00:35.670 --> 00:40.470 it, you assign it a new value in the familiar way here. 00:40.950 --> 00:43.440 So he's size here. 00:43.710 --> 00:45.940 Uh, his size, for example. 00:45.940 --> 00:46.350 Zero. 00:47.750 --> 00:56.920 And so we assigned it now when you try to use up here, up and down arrows to, uh, wrinkle your comments, 00:56.930 --> 01:03.170 nothing happens, happens because the system no longer stores them here, as you can see, and nothing 01:03.170 --> 01:03.860 happens here. 01:04.790 --> 01:08.010 So this is stealthy, although it can be inconvenience. 01:08.030 --> 01:12.920 So I will change this to one thousand back. 01:14.820 --> 01:22.370 So we're making variable value chains permanent, so we are watching an environment variable that change 01:22.440 --> 01:25.090 only occurs in that particular environment. 01:25.110 --> 01:28.410 In this case, the environment is the best shell station. 01:28.680 --> 01:32.340 So this means that you when you close the terminal here, for example. 01:33.120 --> 01:34.830 So when you close the terminal. 01:35.840 --> 01:38.720 Um, any chance you made are lost. 01:38.900 --> 01:44.740 So we were able to set back to their default, so for example, his size one, as you can see in the 01:44.880 --> 01:46.130 last months, is not working. 01:46.430 --> 01:53.100 When they closed that and open it again, for example, as you can see here, we can see ours. 01:53.130 --> 01:54.050 Yes, I see it. 01:54.860 --> 01:59.930 So now we will, uh, change in permanently so. 02:02.080 --> 02:08.200 If you want to make the changes permanent, so you need to use the export command. 02:10.100 --> 02:14.030 So this command will export a new value from your current environment. 02:14.060 --> 02:20.630 This is the best shell to the rest of the system, though, making it available in every environment 02:20.960 --> 02:23.900 until the oil change and export it again. 02:24.710 --> 02:26.060 So variables are strings. 02:26.060 --> 02:33.050 So if you run on the country's side, it's it isn't a bad idea to say the contents of a variable to 02:33.050 --> 02:34.850 it takes one before you modify it. 02:35.270 --> 02:41.840 So, for example, since we were about to change, the P is one variable, uh, which controls the information 02:41.840 --> 02:43.070 we will display in the prompt. 02:43.340 --> 02:50.270 So the first run, the command to save the existing files to have NEG text while in the current user's 02:50.270 --> 02:51.170 home directory. 02:51.440 --> 02:58.720 So Echo here is size and then, uh, this is them. 02:58.730 --> 03:08.150 This means our home directory and the value of our own value of my keys is that the exterior? 03:10.740 --> 03:11.170 Oops! 03:11.950 --> 03:16.050 I actually write and exploit it, so we don't need expert. 03:16.400 --> 03:21.510 So unless unless you can see the value of my, his size is here. 03:21.510 --> 03:25.770 So let's read it with cat common value of my his size. 03:25.770 --> 03:32.040 As you can see, there's a 1000 right at it, so we can open it with MOSFET as well. 03:33.010 --> 03:33.780 Uh, here. 03:34.910 --> 03:37.520 Well, the off my side, as you can see it, let's open it. 03:37.970 --> 03:41.090 And as you can see, there is a one thousand year. 03:42.460 --> 03:43.400 So let's close it. 03:43.420 --> 03:50.830 I will show more examples this way you can always undo your changes if you want to be ever more catalyst 03:50.830 --> 03:57.010 to create a text file with all the current settings, you can save the output of the said commonplace 03:57.010 --> 04:09.970 text file with command like this, for example, set up here the value of all and, for example, time 04:10.330 --> 04:16.480 or oh, let's write our party at eleven forty nine here. 04:17.440 --> 04:21.220 Eleven forty nine and texting. 04:22.230 --> 04:32.730 So let's open it again, or we can add value of all, as you can see, and we printed all of these variables 04:32.730 --> 04:32.970 here. 04:33.330 --> 04:41.700 We can open it with our text for you as well as you can the value of files I can see here we have almost 04:42.090 --> 04:47.200 two hundred thirty eight lines of these set files. 04:48.480 --> 04:55.280 So now that he says, variable is still be set to zero when you live this, uh, environment and international 04:55.410 --> 05:00.710 environment, if you want to raise it here, let's actually change it first to here. 05:01.170 --> 05:08.220 Uh, clear, clear and export Keast size here. 05:09.290 --> 05:13.160 So now that he says variable was said, uh, to zero. 05:13.580 --> 05:18.350 So when you leave this environment and the interim environment, if you want to raise it to his size, 05:18.800 --> 05:29.000 uh, to variable to one thousand, simply enter this, for example, um, his his size as in one thousand 05:29.570 --> 05:32.840 and then export his size. 05:35.500 --> 05:41.110 So this court will set your his side's variables value to one thousand. 05:42.160 --> 05:45.910 And export it to all your environments here.