1 00:00:00,900 --> 00:00:03,390 Changing variable values for a session. 2 00:00:03,930 --> 00:00:09,270 So now now let's see how the changing variables value as not adhered to. 3 00:00:09,270 --> 00:00:14,880 His side's variable contains the value of the number of commands to store in the history file. 4 00:00:15,390 --> 00:00:21,120 Sometimes you won't want your system to save past commands, perhaps because you don't want to leave 5 00:00:21,120 --> 00:00:25,560 any evidence of your activity on your own system or the target system. 6 00:00:25,890 --> 00:00:29,580 So in that case, you can set the his size variable to zero. 7 00:00:29,850 --> 00:00:35,670 So the system will install any of your past commands because this variable has a single value to change 8 00:00:35,670 --> 00:00:40,470 it, you assign it a new value in the familiar way here. 9 00:00:40,950 --> 00:00:43,440 So he's size here. 10 00:00:43,710 --> 00:00:45,940 Uh, his size, for example. 11 00:00:45,940 --> 00:00:46,350 Zero. 12 00:00:47,750 --> 00:00:56,920 And so we assigned it now when you try to use up here, up and down arrows to, uh, wrinkle your comments, 13 00:00:56,930 --> 00:01:03,170 nothing happens, happens because the system no longer stores them here, as you can see, and nothing 14 00:01:03,170 --> 00:01:03,860 happens here. 15 00:01:04,790 --> 00:01:08,010 So this is stealthy, although it can be inconvenience. 16 00:01:08,030 --> 00:01:12,920 So I will change this to one thousand back. 17 00:01:14,820 --> 00:01:22,370 So we're making variable value chains permanent, so we are watching an environment variable that change 18 00:01:22,440 --> 00:01:25,090 only occurs in that particular environment. 19 00:01:25,110 --> 00:01:28,410 In this case, the environment is the best shell station. 20 00:01:28,680 --> 00:01:32,340 So this means that you when you close the terminal here, for example. 21 00:01:33,120 --> 00:01:34,830 So when you close the terminal. 22 00:01:35,840 --> 00:01:38,720 Um, any chance you made are lost. 23 00:01:38,900 --> 00:01:44,740 So we were able to set back to their default, so for example, his size one, as you can see in the 24 00:01:44,880 --> 00:01:46,130 last months, is not working. 25 00:01:46,430 --> 00:01:53,100 When they closed that and open it again, for example, as you can see here, we can see ours. 26 00:01:53,130 --> 00:01:54,050 Yes, I see it. 27 00:01:54,860 --> 00:01:59,930 So now we will, uh, change in permanently so. 28 00:02:02,080 --> 00:02:08,200 If you want to make the changes permanent, so you need to use the export command. 29 00:02:10,100 --> 00:02:14,030 So this command will export a new value from your current environment. 30 00:02:14,060 --> 00:02:20,630 This is the best shell to the rest of the system, though, making it available in every environment 31 00:02:20,960 --> 00:02:23,900 until the oil change and export it again. 32 00:02:24,710 --> 00:02:26,060 So variables are strings. 33 00:02:26,060 --> 00:02:33,050 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 34 00:02:33,050 --> 00:02:34,850 it takes one before you modify it. 35 00:02:35,270 --> 00:02:41,840 So, for example, since we were about to change, the P is one variable, uh, which controls the information 36 00:02:41,840 --> 00:02:43,070 we will display in the prompt. 37 00:02:43,340 --> 00:02:50,270 So the first run, the command to save the existing files to have NEG text while in the current user's 38 00:02:50,270 --> 00:02:51,170 home directory. 39 00:02:51,440 --> 00:02:58,720 So Echo here is size and then, uh, this is them. 40 00:02:58,730 --> 00:03:08,150 This means our home directory and the value of our own value of my keys is that the exterior? 41 00:03:10,740 --> 00:03:11,170 Oops! 42 00:03:11,950 --> 00:03:16,050 I actually write and exploit it, so we don't need expert. 43 00:03:16,400 --> 00:03:21,510 So unless unless you can see the value of my, his size is here. 44 00:03:21,510 --> 00:03:25,770 So let's read it with cat common value of my his size. 45 00:03:25,770 --> 00:03:32,040 As you can see, there's a 1000 right at it, so we can open it with MOSFET as well. 46 00:03:33,010 --> 00:03:33,780 Uh, here. 47 00:03:34,910 --> 00:03:37,520 Well, the off my side, as you can see it, let's open it. 48 00:03:37,970 --> 00:03:41,090 And as you can see, there is a one thousand year. 49 00:03:42,460 --> 00:03:43,400 So let's close it. 50 00:03:43,420 --> 00:03:50,830 I will show more examples this way you can always undo your changes if you want to be ever more catalyst 51 00:03:50,830 --> 00:03:57,010 to create a text file with all the current settings, you can save the output of the said commonplace 52 00:03:57,010 --> 00:04:09,970 text file with command like this, for example, set up here the value of all and, for example, time 53 00:04:10,330 --> 00:04:16,480 or oh, let's write our party at eleven forty nine here. 54 00:04:17,440 --> 00:04:21,220 Eleven forty nine and texting. 55 00:04:22,230 --> 00:04:32,730 So let's open it again, or we can add value of all, as you can see, and we printed all of these variables 56 00:04:32,730 --> 00:04:32,970 here. 57 00:04:33,330 --> 00:04:41,700 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 58 00:04:42,090 --> 00:04:47,200 two hundred thirty eight lines of these set files. 59 00:04:48,480 --> 00:04:55,280 So now that he says, variable is still be set to zero when you live this, uh, environment and international 60 00:04:55,410 --> 00:05:00,710 environment, if you want to raise it here, let's actually change it first to here. 61 00:05:01,170 --> 00:05:08,220 Uh, clear, clear and export Keast size here. 62 00:05:09,290 --> 00:05:13,160 So now that he says variable was said, uh, to zero. 63 00:05:13,580 --> 00:05:18,350 So when you leave this environment and the interim environment, if you want to raise it to his size, 64 00:05:18,800 --> 00:05:29,000 uh, to variable to one thousand, simply enter this, for example, um, his his size as in one thousand 65 00:05:29,570 --> 00:05:32,840 and then export his size. 66 00:05:35,500 --> 00:05:41,110 So this court will set your his side's variables value to one thousand. 67 00:05:42,160 --> 00:05:45,910 And export it to all your environments here.