1 00:00:00,000 --> 00:00:01,290 Being assistant administrator, 2 00:00:01,290 --> 00:00:03,540 you're going to have to do a lot of different tasks. 3 00:00:03,540 --> 00:00:04,590 So it's very important 4 00:00:04,590 --> 00:00:08,010 to be able to automate these tasks using scripts. 5 00:00:08,010 --> 00:00:10,050 So we're going to go through it in this walk through 6 00:00:10,050 --> 00:00:12,810 of how to customize first, our environment 7 00:00:12,810 --> 00:00:16,020 to make it productive for the scripts that we want to run. 8 00:00:16,020 --> 00:00:18,593 So the first command we'll use is environment command. 9 00:00:19,487 --> 00:00:21,150 This is going to give us a list of all the variables 10 00:00:21,150 --> 00:00:23,100 relative to our environment. 11 00:00:23,100 --> 00:00:25,110 The one we're going to focus on here 12 00:00:25,110 --> 00:00:27,213 is the history size, just for an example. 13 00:00:29,640 --> 00:00:30,690 Move towards the top. 14 00:00:31,680 --> 00:00:34,800 So you can see the history size is 1000, 15 00:00:34,800 --> 00:00:37,950 meaning that's going to store the last 1000 commands 16 00:00:37,950 --> 00:00:39,360 but we're going to change that. 17 00:00:39,360 --> 00:00:42,690 Now, another way to view variables, 18 00:00:42,690 --> 00:00:44,370 is just use the dollar sign. 19 00:00:44,370 --> 00:00:46,440 I'm going to use this command, echo. 20 00:00:46,440 --> 00:00:48,000 And it's going to tell us exactly 21 00:00:48,000 --> 00:00:50,850 what the value of that variable is 22 00:00:50,850 --> 00:00:54,453 because how the variables are set up are key value pairs. 23 00:00:55,500 --> 00:00:58,110 So the key is going to be histsize, 24 00:00:58,110 --> 00:01:01,053 the value is going to be 1000 and we're about to change that. 25 00:01:02,288 --> 00:01:03,363 We see the history. 26 00:01:05,489 --> 00:01:07,640 We see we have a lot of different commands. 27 00:01:08,520 --> 00:01:11,100 So in order to change the variable, 28 00:01:11,100 --> 00:01:13,203 we're going to use the export command. 29 00:01:16,024 --> 00:01:17,850 Now we're just going to use a low value 30 00:01:17,850 --> 00:01:19,983 just to make the demonstration easier. 31 00:01:21,360 --> 00:01:22,860 So just going to run a few commands. 32 00:01:22,860 --> 00:01:27,463 We're going to do echo one. 33 00:01:38,635 --> 00:01:40,823 All right, so if we scroll up with our arrow, 34 00:01:43,080 --> 00:01:45,120 we see we only stop at three, 35 00:01:45,120 --> 00:01:47,070 'cause clear is also a command, right? 36 00:01:47,070 --> 00:01:51,660 So, one, two, three, four, five. 37 00:01:51,660 --> 00:01:53,010 Can't go anymore than that. 38 00:01:53,010 --> 00:01:55,710 So test that out. 39 00:01:55,710 --> 00:01:57,690 So next thing we're going to do, we're going to make a directory 40 00:01:57,690 --> 00:01:59,140 to actually hold our scripts. 41 00:02:04,710 --> 00:02:06,060 Okay. 42 00:02:06,060 --> 00:02:09,000 And I have a script currently in my directory. 43 00:02:09,000 --> 00:02:11,693 We're going to move it to the scripts folder. 44 00:02:11,693 --> 00:02:12,690 Okay, going to do sudo, 45 00:02:12,690 --> 00:02:14,343 since it's in the root directory. 46 00:02:24,180 --> 00:02:25,480 Make sure they went there. 47 00:02:30,390 --> 00:02:32,730 Now, one thing that's important to note, 48 00:02:32,730 --> 00:02:35,250 we need to change the permissions on here 49 00:02:35,250 --> 00:02:37,353 if we're going to execute this script. 50 00:02:38,340 --> 00:02:40,403 So just going to do a change mod really quick. 51 00:02:49,380 --> 00:02:51,003 Going to do 775 right now. 52 00:02:52,020 --> 00:02:53,550 All right. 53 00:02:53,550 --> 00:02:55,320 Now, one thing we have to worry about 54 00:02:55,320 --> 00:02:58,290 when we're using scripts is the path variable. 55 00:02:58,290 --> 00:03:01,320 So the path variable lets the system know 56 00:03:01,320 --> 00:03:04,320 where are these commands located when you just type them up. 57 00:03:05,310 --> 00:03:10,310 So for example, when we type in just clear or last log, 58 00:03:10,890 --> 00:03:12,750 these commands are stored somewhere. 59 00:03:12,750 --> 00:03:14,670 And in order for the system to know where it's located, 60 00:03:14,670 --> 00:03:17,850 we must set that in our path variable. 61 00:03:17,850 --> 00:03:18,690 So first let's just see 62 00:03:18,690 --> 00:03:20,730 what our path variable looks like now. 63 00:03:20,730 --> 00:03:22,880 It's going to be a list of multiple variables. 64 00:03:24,540 --> 00:03:26,250 So these are all the possible locations 65 00:03:26,250 --> 00:03:30,480 that Linux will look to see how to execute that command. 66 00:03:30,480 --> 00:03:31,680 All right, now to change that for us, 67 00:03:31,680 --> 00:03:34,080 we're going to look at our bash profile command. 68 00:03:34,080 --> 00:03:36,633 So we're going to vim. 69 00:03:41,100 --> 00:03:43,200 All right, so we need to export this path. 70 00:03:48,600 --> 00:03:49,433 And we're going to make sure 71 00:03:49,433 --> 00:03:51,080 that we include the current variable. 72 00:03:52,590 --> 00:03:54,880 And then we're also going to add the scripts 73 00:03:56,550 --> 00:03:58,020 'cause that's where the script 74 00:03:58,020 --> 00:04:01,080 that we just moved to the scripts folder is located. 75 00:04:01,080 --> 00:04:02,190 So by the end of this, 76 00:04:02,190 --> 00:04:05,370 we're going to be able to type echo.sh 77 00:04:05,370 --> 00:04:07,530 and the system's going to know where to locate it 78 00:04:07,530 --> 00:04:08,880 and how to run it. 79 00:04:08,880 --> 00:04:13,710 Okay, now one thing we must do is use this source command 80 00:04:13,710 --> 00:04:17,490 and that's going to pretty much reload the bash.profile 81 00:04:17,490 --> 00:04:19,200 so the system knows to re-look 82 00:04:19,200 --> 00:04:21,300 at the new configuration file. 83 00:04:21,300 --> 00:04:24,217 Okay, now let's look at the path variable now. 84 00:04:26,320 --> 00:04:28,950 Okay, now we see what's added at the bottom. 85 00:04:28,950 --> 00:04:31,743 You see after the last colon, we see a /scripts. 86 00:04:32,730 --> 00:04:34,170 Now let's try that bad boy out. 87 00:04:34,170 --> 00:04:35,640 Do echo.sh. 88 00:04:35,640 --> 00:04:39,030 All right, well we see that went through successfully. 89 00:04:39,030 --> 00:04:42,480 Again, that script simply just prints out different lines 90 00:04:42,480 --> 00:04:44,133 just for the sake of the example. 91 00:04:45,390 --> 00:04:47,550 So if you want to check it out, see what it looks like, 92 00:04:47,550 --> 00:04:48,383 you just do cat. 93 00:04:51,935 --> 00:04:54,120 And you see that's how a script looks. 94 00:04:54,120 --> 00:04:55,770 And again, if you just look at the lines 95 00:04:55,770 --> 00:04:58,170 after the first one, where you see echo commands, 96 00:04:58,170 --> 00:04:59,340 just print out things 97 00:04:59,340 --> 00:05:00,810 and then see that the system will run it 98 00:05:00,810 --> 00:05:03,543 just by typing in the command without anything prior. 99 00:05:04,980 --> 00:05:07,920 Now the last one we'll go over is how to create an alias 100 00:05:07,920 --> 00:05:11,130 for a lengthy command that we typically use. 101 00:05:11,130 --> 00:05:14,730 So for example, I'm going to use this last log command 102 00:05:14,730 --> 00:05:18,210 which shows the last login for all the users. 103 00:05:18,210 --> 00:05:21,280 The tail, meaning that we're going to start 104 00:05:23,160 --> 00:05:24,250 with the second line 105 00:05:25,965 --> 00:05:27,480 and we're going to sort it 106 00:05:27,480 --> 00:05:29,480 by the first line in alphabetical order. 107 00:05:31,380 --> 00:05:32,213 Okay. 108 00:05:35,910 --> 00:05:37,710 Typically we have the header at the top, 109 00:05:37,710 --> 00:05:39,930 the username and the time, 110 00:05:39,930 --> 00:05:41,130 but we just want the information 111 00:05:41,130 --> 00:05:43,350 so that's why we started with line number two. 112 00:05:43,350 --> 00:05:44,670 And we see this in the alphabetical order 113 00:05:44,670 --> 00:05:46,563 based off the username or process. 114 00:05:50,160 --> 00:05:52,410 Now we don't want to have to type it all the time. 115 00:05:52,410 --> 00:05:56,253 So what we can do is run a change in our .bashrc file. 116 00:06:00,630 --> 00:06:02,160 If you look at the last section 117 00:06:02,160 --> 00:06:04,590 as user specific aliases and functions, 118 00:06:04,590 --> 00:06:06,023 that's where we're going to input that. 119 00:06:07,320 --> 00:06:08,223 Type in alias. 120 00:06:09,720 --> 00:06:10,680 Going to name it ulog. 121 00:06:13,830 --> 00:06:15,383 This where we're going to type in the command. 122 00:06:33,570 --> 00:06:35,470 Again, we must run our source command. 123 00:06:38,160 --> 00:06:40,650 All right, now we have reloaded that configuration 124 00:06:40,650 --> 00:06:41,750 and now let's type it. 125 00:06:43,290 --> 00:06:46,410 And you can see the alias ran the full command for us. 126 00:06:46,410 --> 00:06:47,670 So we just walked through a quick way 127 00:06:47,670 --> 00:06:49,470 of how to set up our shell environment 128 00:06:49,470 --> 00:06:51,810 to make scripts and alias for different commands 129 00:06:51,810 --> 00:06:53,520 to make it easier for us to run 130 00:06:53,520 --> 00:06:56,760 and make our jobs easier as system administrators. 131 00:06:56,760 --> 00:06:58,170 Thank you for sticking with this walkthrough 132 00:06:58,170 --> 00:06:59,970 and I'll see you in the next lesson.