WEBVTT 1 00:00:00.120 --> 00:00:02.680 Okay, So for anyone trying to get their head around 2 00:00:02.680 --> 00:00:07.639 Linux system administration, you know, it can feel like this 3 00:00:07.799 --> 00:00:10.160 huge amount of information right, almost. 4 00:00:09.839 --> 00:00:11.839 Overwhelming, totally, it's amazing. 5 00:00:11.960 --> 00:00:14.679 Yeah, and you need to get up to speed, like fast, 6 00:00:14.960 --> 00:00:17.120 but cut through all the noise really get to the 7 00:00:17.120 --> 00:00:20.239 heart of it. Well, today, that's what we're doing. We're 8 00:00:20.239 --> 00:00:22.679 taking a deep dive into a stack of sources that 9 00:00:22.719 --> 00:00:26.000 are designed to help you not just you know, learn Linux, 10 00:00:26.079 --> 00:00:28.239 but actually start thinking like a linux's admin. 11 00:00:28.359 --> 00:00:30.559 And what's really cool about these sources, I think is 12 00:00:30.600 --> 00:00:34.159 they don't just give you the what, the commands and tasks. 13 00:00:34.280 --> 00:00:35.600 They dig into the. 14 00:00:35.479 --> 00:00:39.920 Why, the philosophy behind it, exactly why does Linux work 15 00:00:39.960 --> 00:00:42.560 this way, We're going to explore that core philosophy, look 16 00:00:42.560 --> 00:00:45.240 at the really essential tools, and even touch on the 17 00:00:46.000 --> 00:00:49.000 mindset you need. It's like a shortcut, kind of yeah, 18 00:00:49.200 --> 00:00:52.439 a shortcut to not just knowing facts, but actually understanding 19 00:00:52.479 --> 00:00:55.840 this whole critical ecosystem that, let's face it, runs a 20 00:00:55.920 --> 00:00:57.479 huge chunk of our modern world. 21 00:00:57.799 --> 00:01:00.679 Okay, So our mission here then is to really boil 22 00:01:00.759 --> 00:01:04.319 down these essential principles, the key tools, the best practices 23 00:01:04.560 --> 00:01:08.680 for linuxes admen. We want to give you insights, practical 24 00:01:08.680 --> 00:01:11.879 stuff you can use that goes way beyond just scratching 25 00:01:11.920 --> 00:01:14.319 the surface. Well, look at why Linux is built like 26 00:01:14.359 --> 00:01:16.640 it is, how that design gives you so much control, 27 00:01:16.959 --> 00:01:19.640 and what it actually means to work with a system 28 00:01:19.640 --> 00:01:23.879 that's fundamentally built on trust and openness. So kicking off 29 00:01:24.159 --> 00:01:28.200 the source material jumps right into this really interesting comparison 30 00:01:28.799 --> 00:01:31.519 the whole black box versus open box thing in software. 31 00:01:31.640 --> 00:01:32.760 Yeah, that's fundamental. 32 00:01:32.920 --> 00:01:35.959 I mean, can you imagine relying on tools where you just, yeah, 33 00:01:36.040 --> 00:01:38.480 you can't see inside, you can't really understand how they 34 00:01:38.560 --> 00:01:39.480 work exactly. 35 00:01:40.120 --> 00:01:44.159 And the sources talk about this black box syndrome you 36 00:01:44.200 --> 00:01:48.079 often find in proprietary software, you know, like Windows for example. Right, 37 00:01:48.239 --> 00:01:51.079 the insides are basically hidden. Something goes wrong, and what's 38 00:01:51.120 --> 00:01:52.280 the usual advice. 39 00:01:52.000 --> 00:01:53.879 As you tried turning it off and on again. 40 00:01:53.599 --> 00:01:56.640 Pretty much just reboot because you can't actually figure out 41 00:01:56.680 --> 00:01:58.359 what's really happening in there. It's sealed off. 42 00:01:58.439 --> 00:01:58.760 Okay. 43 00:01:58.920 --> 00:02:02.319 Now, contrast that with the open box idea of open source. 44 00:02:02.599 --> 00:02:05.519 You can see the code precisely, you get the source code, 45 00:02:05.599 --> 00:02:07.480 you can look at it, you can understand it, you 46 00:02:07.519 --> 00:02:09.960 can even fix it yourself if you need to Wow, 47 00:02:10.080 --> 00:02:12.800 there's a great little story and the sources about openofice 48 00:02:12.800 --> 00:02:16.680 dot org. When the ownership changed and things went in 49 00:02:16.680 --> 00:02:20.479 a direction some developers didn't like what happened. Well, because 50 00:02:20.520 --> 00:02:22.879 it was open source, they could just take the code, 51 00:02:23.120 --> 00:02:25.680 fork it and start a new project LibreOffice. 52 00:02:26.000 --> 00:02:28.439 Ah right, I use libra office. 53 00:02:28.560 --> 00:02:30.439 Yeah. They just picked up the code and kept going. 54 00:02:30.759 --> 00:02:33.159 That's the power of having that open box. You're not 55 00:02:33.199 --> 00:02:33.680 locked in. 56 00:02:33.919 --> 00:02:36.879 And that leads right into what the source is called 57 00:02:36.879 --> 00:02:40.319 the Linux Truth, which sounds quite grand. 58 00:02:40.439 --> 00:02:43.080 It does, doesn't it, But the core idea is simple. Really, 59 00:02:43.439 --> 00:02:45.479 the operating system has to trust the user. 60 00:02:45.800 --> 00:02:48.280 Unlike systems that maybe try to protect you from yourself 61 00:02:48.280 --> 00:02:49.199 too much exactly. 62 00:02:49.240 --> 00:02:52.560 Some systems put up guardrails, they limit what you can access, 63 00:02:52.560 --> 00:02:55.800 what you can change. Linux fundamentally doesn't. 64 00:02:55.919 --> 00:02:59.840 It trusts you, which gives a cisadmin huge flexibility. 65 00:02:59.360 --> 00:03:02.000 Immense stability. Even as the sources kind of joke when 66 00:03:02.039 --> 00:03:04.599 you do stupid things. It assumes you know what you're doing, 67 00:03:04.680 --> 00:03:07.319 or that you're willing to learn from mistakes. It gives 68 00:03:07.360 --> 00:03:08.039 you the power. 69 00:03:08.159 --> 00:03:11.159 And this goes way back right to the very beginning. 70 00:03:11.199 --> 00:03:15.120 Oh yeah, absolutely, it's bigd in Linus Torvald's back in 71 00:03:15.199 --> 00:03:17.800 ninety one. He started Linux because he wasn't happy with 72 00:03:17.879 --> 00:03:22.080 Minnix's limitations right and crucially he shared it openly from 73 00:03:22.120 --> 00:03:24.759 the get go. But even that wasn't totally new. It 74 00:03:24.840 --> 00:03:28.719 really followed the spirit of UNIXI Okay, Ken Thompson, Dennis Ritchie. 75 00:03:29.280 --> 00:03:32.479 They designed Unix to be open accessible right from its 76 00:03:32.520 --> 00:03:35.520 own start. It's a philosophical lineage, not just code. 77 00:03:35.840 --> 00:03:38.879 So that openness it connects to this idea of freedom 78 00:03:39.000 --> 00:03:42.199 in open source, which isn't just about cost, is it? 79 00:03:42.400 --> 00:03:46.120 No, definitely not. It's the classic distinction free as in freedom, 80 00:03:46.199 --> 00:03:47.199 not just free as in. 81 00:03:47.159 --> 00:03:49.319 Beer, meaning you can use it, change. 82 00:03:49.080 --> 00:03:52.080 It, use it, study it, modify it, share it. That 83 00:03:52.199 --> 00:03:56.080 freedom has real world consequences like what well, For one, 84 00:03:56.120 --> 00:03:58.479 it fights against planned ops lescence. 85 00:03:58.120 --> 00:04:01.319 Ah, when things are designed to break or come outdated. 86 00:04:01.080 --> 00:04:05.000 Exactly the sources mentioned, keeping like twelve year old laptops 87 00:04:05.080 --> 00:04:08.080 or ten year old netbooks perfectly usable. 88 00:04:07.759 --> 00:04:10.439 Because you can run up to date secure software on 89 00:04:10.639 --> 00:04:11.400 older hardware. 90 00:04:11.560 --> 00:04:14.919 Precisely, you're not forced into hardware upgrades just to run 91 00:04:14.960 --> 00:04:18.680 the latest os. And this philosophy, this power. Look where 92 00:04:18.680 --> 00:04:22.279 Linux is now everywhere pretty much since twenty seventeen. It 93 00:04:22.360 --> 00:04:26.439 runs one hundred percent of the world's top five hundred supercomputers. Wow, 94 00:04:26.639 --> 00:04:29.839 it's on the International Space Station. It's the base for 95 00:04:29.959 --> 00:04:33.120 Android on billions of phones. It's in your smart TV. 96 00:04:33.360 --> 00:04:35.199 It's the engine driving the Internet. 97 00:04:35.360 --> 00:04:38.639 So it scales from tiny devices to massive. 98 00:04:38.279 --> 00:04:42.600 Systems, effortlessly watches to supercomputers. It's incredibly versatile. 99 00:04:42.639 --> 00:04:46.000 Okay, and shifting gears slightly, but still related to efficiency. 100 00:04:46.560 --> 00:04:49.680 The sources talk about this lazy cisadmin philosophy, which sounds 101 00:04:49.759 --> 00:04:51.560 bad but isn't. 102 00:04:51.680 --> 00:04:55.079 Huh, Yeah, it sounds wrong, but it's actually about being smart, 103 00:04:55.120 --> 00:04:58.600 really smart. Also, lazy here means you automate everything if 104 00:04:58.639 --> 00:05:00.959 you do a task more than once script it it 105 00:05:01.000 --> 00:05:04.879 means you test things thoroughly, early and often and controversially. 106 00:05:04.920 --> 00:05:07.399 Maybe it even means sometimes you test in production. 107 00:05:07.800 --> 00:05:09.560 Really isn't that risky? 108 00:05:09.720 --> 00:05:12.399 It can be, but the idea is the real world 109 00:05:12.439 --> 00:05:15.199 often shows you things a sterilab environment won't. It's about 110 00:05:15.199 --> 00:05:19.279 building robust, self healing systems that don't need constant manual poking. 111 00:05:19.720 --> 00:05:22.480 So the laziness is about reducing future. 112 00:05:22.160 --> 00:05:25.800 Work exactly, freeing yourself up from firefighting to do more 113 00:05:25.839 --> 00:05:29.240 strategic work. And it even comes down to simple things 114 00:05:29.279 --> 00:05:33.199 like common sense naming for files and commands to save typing, 115 00:05:33.319 --> 00:05:37.279 to save typing, and crucially to reduce errors, less typing, 116 00:05:37.600 --> 00:05:38.480 fewer mistakes. 117 00:05:38.800 --> 00:05:43.680 So thinking about all this, this philosophy, this mindset, maybe 118 00:05:43.720 --> 00:05:46.920 you listening right now should reflect do you have some 119 00:05:47.000 --> 00:05:47.720 of these traits? 120 00:05:48.079 --> 00:05:49.199 Yeah, it's a good question. 121 00:05:49.519 --> 00:05:52.600 Are you naturally curious? Do you like taking things apart 122 00:05:52.680 --> 00:05:53.639 just to see how they tick? 123 00:05:53.839 --> 00:05:55.480 Not just what they are, but how they work? 124 00:05:55.800 --> 00:06:00.639 Right? Do you find computers maybe more logical or predict people? 125 00:06:00.680 --> 00:06:02.920 Sometimes a common CIS admin trade. 126 00:06:02.959 --> 00:06:05.800 Perhaps do you really like having control over your tools, 127 00:06:05.839 --> 00:06:08.639 your environment? And do you actually get what open source 128 00:06:08.720 --> 00:06:10.560 means beyond just free stuff? 129 00:06:10.720 --> 00:06:13.560 If those resonate, maybe you've got the CIS admin's spark. 130 00:06:13.839 --> 00:06:16.160 Okay, So building on that philosophy, let's dig into the 131 00:06:16.199 --> 00:06:21.079 actual components. What is Linux under the hood? Because the 132 00:06:21.120 --> 00:06:24.920 sources are clear, that graphical desktop the thing most people see, 133 00:06:25.240 --> 00:06:26.279 that's just the surface. 134 00:06:26.519 --> 00:06:30.399 Absolutely, it's just the visible part. The real power lies beneath. 135 00:06:30.680 --> 00:06:32.000 So what are the fundamentals? 136 00:06:32.279 --> 00:06:37.600 Well, any os basically manages hardware, right, your CPU, your RAM, 137 00:06:37.639 --> 00:06:40.519 that's the fast volatile memory that forgets everything when you 138 00:06:40.560 --> 00:06:43.759 power off, right versus storage exactly. Yeah, and your hard 139 00:06:43.839 --> 00:06:48.240 drives or SSDs, the non volatile storage. The OS coordinates 140 00:06:48.279 --> 00:06:48.560 all that. 141 00:06:48.920 --> 00:06:50.600 And in Linux, the core, the. 142 00:06:50.600 --> 00:06:54.680 Absolute heart is the Linux kernel. That's Linus Torvald's original creation, 143 00:06:54.920 --> 00:06:58.000 constantly evolving. Okay, but the kernel alone isn't enough to 144 00:06:58.079 --> 00:07:00.240 do much. You need the tools, and that's where the 145 00:07:00.319 --> 00:07:01.959 G and U core utilities come. 146 00:07:01.800 --> 00:07:03.759 In, developed by Richard Stallman and others. 147 00:07:03.879 --> 00:07:07.079 That's right, an enormous collection of essential command line tools. 148 00:07:07.399 --> 00:07:11.000 The kernel plus these utilities working together, that's what really 149 00:07:11.040 --> 00:07:13.279 makes up the Linux operating system you interact with. 150 00:07:13.560 --> 00:07:17.199 Okay, now, for maybe one of the weirdest but coolest 151 00:07:17.680 --> 00:07:20.759 Linux ideas, everything is a file. 152 00:07:21.120 --> 00:07:23.800 Huh Yeah. It bends your brain a bit at first. 153 00:07:23.839 --> 00:07:26.360 What does that actually mean? How can hardware be a file? 154 00:07:26.480 --> 00:07:29.680 It's a really powerful abstraction. It means the system represents 155 00:07:29.720 --> 00:07:34.439 almost everything hardware, devices, network connections, processes, you name it, 156 00:07:34.759 --> 00:07:36.199 using the same file interface. 157 00:07:36.279 --> 00:07:38.519 So you interact with them like files pretty much. 158 00:07:38.839 --> 00:07:41.680 Think about devices. They show up as special files in 159 00:07:41.720 --> 00:07:44.920 the dev directory. Okay, so your hard drive might be DESDA, 160 00:07:45.079 --> 00:07:48.160 a partition devsdo one, and because it looks like a file, 161 00:07:48.560 --> 00:07:51.720 you can do things directly to it, like what well 162 00:07:51.839 --> 00:07:54.639 The sources mentioned treating an entire hard drive as a 163 00:07:54.639 --> 00:07:57.560 single file. This makes things like making a perfect byte 164 00:07:57.560 --> 00:08:01.120 for byte copy or securely wiping data using commands like 165 00:08:01.240 --> 00:08:03.959 DD or shred surprisingly straightforward. 166 00:08:04.240 --> 00:08:06.759 You're just writing data to a file exactly. 167 00:08:06.600 --> 00:08:09.279 Or reading from it. The sources even point to de 168 00:08:09.519 --> 00:08:12.160 random and de random. These are literally files you can 169 00:08:12.199 --> 00:08:14.480 read from to get a stream of random numbers. 170 00:08:14.519 --> 00:08:17.639 That's wild. So if the gy isn't the main way 171 00:08:17.639 --> 00:08:20.959 in and everything's a file, how do we actually talk 172 00:08:21.000 --> 00:08:22.680 to linox? How does sisadmins work? 173 00:08:22.879 --> 00:08:26.439 Good question? The command line is key, and there are 174 00:08:26.480 --> 00:08:28.600 basically three main ways to get to it. 175 00:08:28.639 --> 00:08:29.000 Okay. 176 00:08:29.040 --> 00:08:32.799 First, you've got your graphical terminal emulators. These are applications 177 00:08:32.799 --> 00:08:37.240 that run inside your desktop environment, like as four terminal. 178 00:08:37.360 --> 00:08:41.000 The sources like its tabs or others like tillicks or console. 179 00:08:40.759 --> 00:08:42.360 Right the little black window pretty much. 180 00:08:42.720 --> 00:08:46.440 Second, there are virtual consoles. These are text only logins 181 00:08:46.440 --> 00:08:48.759 you can switch to even if your graphical system isn't running. 182 00:08:49.240 --> 00:08:53.440 Super useful for fixing things. Third, for connecting to other machines. 183 00:08:53.519 --> 00:08:58.360 You use remote login primarily SSH secure shell. It's replaced 184 00:08:58.440 --> 00:09:00.799 older insecure things like telnet. 185 00:09:00.799 --> 00:09:05.759 Got it, And there's some specific terminology here terminal console shell. 186 00:09:05.960 --> 00:09:08.120 Yeah, it can be confusing, but it helps to be precise. 187 00:09:08.279 --> 00:09:12.120 Think of the terminal as maybe the physical keyboard and screen. Historically, 188 00:09:12.519 --> 00:09:15.320 the console is often used for that primary direct interface. 189 00:09:15.840 --> 00:09:18.639 The shell is the program that actually interprets your commands. 190 00:09:19.480 --> 00:09:22.120 Bash is the most common one. Bash okay, and a 191 00:09:22.279 --> 00:09:25.080 session is your entire interaction from the moment you log 192 00:09:25.120 --> 00:09:27.879 in until you log out. Knowing the difference helps you 193 00:09:27.919 --> 00:09:29.480 diagnose where a problem might be. 194 00:09:29.679 --> 00:09:33.799 And Bash itself the default shell. It uses those short 195 00:09:33.840 --> 00:09:36.960 command names fitting that leezy admin idea. 196 00:09:36.720 --> 00:09:40.279 Absolutely, LSE for list, CP for copy, MV for move. 197 00:09:40.919 --> 00:09:42.600 It's all about efficiency, and. 198 00:09:42.519 --> 00:09:45.759 These commands come from those core utilities you mentioned primarily. 199 00:09:45.879 --> 00:09:48.600 Yes, they fall into two main buckets, the G and 200 00:09:48.679 --> 00:09:52.799 U core utilities basic stuff for files, text shell operations, 201 00:09:53.200 --> 00:09:56.559 and the utel Linux package open that one. More system 202 00:09:56.639 --> 00:09:59.559 level things like mount for file systems, f disc or 203 00:09:59.759 --> 00:10:04.039 LA BLK for discs, wellicle for a calendar. Really fundamental 204 00:10:04.080 --> 00:10:07.879 tools indispensable basically totally. The sources say flat out without 205 00:10:07.879 --> 00:10:10.720 them it is not possible to accomplish any useful work. 206 00:10:10.960 --> 00:10:14.039 You literally can't run a Linux system without them. Digging 207 00:10:14.080 --> 00:10:15.960 into them with the info command is a great way 208 00:10:16.000 --> 00:10:16.360 to learn. 209 00:10:16.559 --> 00:10:18.799 Okay, so we have the philosophy, the core parts, the 210 00:10:18.799 --> 00:10:21.600 basic tools. Now how do you actually use all this 211 00:10:21.600 --> 00:10:23.600 to solve problems? What's the cysadmin process? 212 00:10:23.840 --> 00:10:27.000 The sources lay out a nice, almost scientific algorithm for 213 00:10:27.080 --> 00:10:27.919 problem solving. 214 00:10:28.200 --> 00:10:29.840 Oh really, like a formula sort of. 215 00:10:29.879 --> 00:10:34.480 It goes knowledge, observation, hypothesize, test, conclude. 216 00:10:34.799 --> 00:10:36.000 Okay, break that down right. 217 00:10:36.120 --> 00:10:39.440 So knowledge is what you already know about how systems work. 218 00:10:39.919 --> 00:10:43.240 Observation is gathering data. What are the symptoms, what do 219 00:10:43.320 --> 00:10:46.399 the logs say? What are the monitoring tools showing. 220 00:10:46.159 --> 00:10:47.919 Like using top maybe exactly? 221 00:10:48.679 --> 00:10:52.879 Then you hypothesize, based on your knowledge and observations, what 222 00:10:52.960 --> 00:10:56.120 do you think the cause is. Then you test your hypothesis, 223 00:10:56.320 --> 00:11:00.240 try a fix, change a setting, and finally you conclude 224 00:11:00.440 --> 00:11:03.759 did the test work? Did it confirm or deny your hypothesis? 225 00:11:03.799 --> 00:11:05.279 And it's not always linear. 226 00:11:05.240 --> 00:11:08.600 Oh definitely not. It's iterative. You often loop back. Your 227 00:11:08.639 --> 00:11:12.000 test might give you new observations leading to a new hypothesis, 228 00:11:12.320 --> 00:11:14.360 or you realize your initial knowledge was incomplete. 229 00:11:14.480 --> 00:11:14.759 Right. 230 00:11:14.879 --> 00:11:17.480 There's actually a funny anecdote in the sources about fixing 231 00:11:17.519 --> 00:11:20.320 a big old mainframe but sitting on the Prinker control 232 00:11:20.399 --> 00:11:23.320 unit sitting on it. Yeah, turns out a cable was 233 00:11:23.399 --> 00:11:27.000 loose and the weight receded it. It's a slightly silly example, 234 00:11:27.000 --> 00:11:30.799 but it underlines how crucial observation is sometimes in unexpected ways. 235 00:11:31.080 --> 00:11:34.840 Huh okay, So observation is key. What are the go 236 00:11:34.879 --> 00:11:38.000 to tools for that? For a monitoring system health. 237 00:11:37.879 --> 00:11:40.879 Well, for real time process monitoring, TOP is the classic, 238 00:11:41.240 --> 00:11:44.039 but EAH TOP and a cop are often preferred now 239 00:11:44.080 --> 00:11:46.200 they're more user friendly, more informative. 240 00:11:46.279 --> 00:11:47.399 What are you looking for with those? 241 00:11:47.639 --> 00:11:51.720 Key things? Are CPUs with zero percent idle time? That 242 00:11:51.799 --> 00:11:55.440 means they're totally swamped. High memory usage is another flag, 243 00:11:55.639 --> 00:11:58.440 especially if the system starts using swap space heavily. 244 00:11:58.639 --> 00:12:02.080 Swamp is like emergency re on the hard drive right, slows. 245 00:12:01.799 --> 00:12:05.519 Things down exactly. It's slow, so high swap usage usually 246 00:12:05.519 --> 00:12:08.399 means you're running out of RAM. These tools also help 247 00:12:08.440 --> 00:12:12.159 you spot specific CPU hog processes that might be causing 248 00:12:12.200 --> 00:12:12.840 the slow. 249 00:12:12.559 --> 00:12:14.320 Down, and once you find a hog. 250 00:12:14.279 --> 00:12:16.759 You can use commands like kill to terminate it if 251 00:12:16.799 --> 00:12:19.840 necessary or re nice to lower its priority, making it 252 00:12:19.879 --> 00:12:23.399 play nicer with others. Gives you direct control over resource usage. 253 00:12:23.480 --> 00:12:26.519 Okay, this next one sounds fascinating looking inside the running 254 00:12:26.559 --> 00:12:28.919 system using PROC like reading its mind. 255 00:12:29.120 --> 00:12:30.960 That's a great way to think about it. PROC is 256 00:12:31.000 --> 00:12:34.159 a virtual filesystem, a window into the kernel. 257 00:12:34.320 --> 00:12:36.639 The sources call it, and it uses that everything is 258 00:12:36.679 --> 00:12:38.559 a file idea again perfectly. 259 00:12:38.720 --> 00:12:41.159 You don't need special tools. You can just use standard 260 00:12:41.159 --> 00:12:43.320 commands like cat to read files directly out. 261 00:12:43.159 --> 00:12:44.759 Of prock like what kind of files? 262 00:12:44.879 --> 00:12:48.399 Things like proc meminfo gives you detailed memory stats. PROC 263 00:12:48.480 --> 00:12:52.720 and winfo tells you all about your processor. Proclodav shows 264 00:12:52.720 --> 00:12:55.120 the system load. It's real time info straight from the 265 00:12:55.159 --> 00:12:57.960 kernel just by reading a file. Incredibly elegant. 266 00:12:58.039 --> 00:13:02.559 Wow. Okay. Switching from the live system to hardware health, 267 00:13:02.600 --> 00:13:05.879 specifically hard drives. They fail eventually. How can we predict that? 268 00:13:06.080 --> 00:13:08.360 Yeah, drive failure is a big one. That's where smart 269 00:13:08.360 --> 00:13:12.960 comes in, self monitoring, analysis, and reporting technology built into 270 00:13:13.000 --> 00:13:16.679 most drives, most modern drives. Yeah, and utilities like smartphone 271 00:13:16.679 --> 00:13:19.480 will let you query that smart data. The goal is 272 00:13:19.519 --> 00:13:21.799 to predict hard drive failures before they happen. 273 00:13:21.960 --> 00:13:22.879 How reliable is that? 274 00:13:23.279 --> 00:13:25.720 Well? The sources mentioned a study by a cloud storage 275 00:13:25.720 --> 00:13:29.559 company looking at tens of thousands of drives. They pinpointed 276 00:13:29.679 --> 00:13:32.039 five specific smart attributes. 277 00:13:32.120 --> 00:13:32.519 Just five. 278 00:13:32.600 --> 00:13:35.399 Yeah, smart ads five, one eighty seven, one eighty eight, 279 00:13:35.480 --> 00:13:38.200 one ninety seven, and one ninety eight. If the raw 280 00:13:38.279 --> 00:13:42.320 values for these start showing high numbers or increasing quickly, yeah, 281 00:13:42.360 --> 00:13:45.200 it's a strong sign that the drive is degrading. Time 282 00:13:45.240 --> 00:13:48.759 to back up and plan a replacement, probably sooner rather 283 00:13:48.799 --> 00:13:51.360 than later. It's not fool proof, but it's a very 284 00:13:51.480 --> 00:13:53.120 valuable early warning. 285 00:13:53.279 --> 00:13:58.080 Good to know. Okay, Beyond monitoring data day systemin work 286 00:13:58.080 --> 00:14:01.679 involves a lot of text file manipulation from the command line. 287 00:14:01.879 --> 00:14:04.840 Oh absolutely, it's bread and butter. Linux is brilliant at this. 288 00:14:05.320 --> 00:14:07.919 You've got data streams and pipes. The little vertical bar 289 00:14:08.039 --> 00:14:11.600 symbol A that lets you chain commands, cat a file 290 00:14:11.679 --> 00:14:14.559 to display it, then pipe its output into WC to 291 00:14:14.679 --> 00:14:18.399 count words or lines. Super powerful for transforming data on 292 00:14:18.440 --> 00:14:18.720 the fly. 293 00:14:18.960 --> 00:14:21.519 And redirection The angle brackets. 294 00:14:21.159 --> 00:14:25.039 YEP redirects output to a file overwriting. It appends to 295 00:14:25.120 --> 00:14:28.360 a file and feeds a file into a command as input. 296 00:14:28.679 --> 00:14:31.159 Essential for saving results or processing data files. 297 00:14:31.200 --> 00:14:32.840 Then there's matching filemames. 298 00:14:32.440 --> 00:14:35.759 File globbing using wild cards like for any characters, for 299 00:14:35.799 --> 00:14:38.759 a single character, for range of characters, or for specific options. 300 00:14:39.039 --> 00:14:41.080 Lets you work on groups of files really. 301 00:14:40.840 --> 00:14:43.080 Efficiently, and searching inside files. 302 00:14:43.399 --> 00:14:46.519 That's rep It's indispensable. You feed it a pattern and 303 00:14:46.600 --> 00:14:49.799 it finds lines containing that pattern in files. You can 304 00:14:49.799 --> 00:14:55.559 search multiple files, ignore case use complex patterns. It's incredibly versatile. 305 00:14:55.600 --> 00:14:58.879 Okay, And if GRIP is for file content, what about 306 00:14:58.960 --> 00:15:02.480 finding files based on other things like size or date. 307 00:15:02.399 --> 00:15:05.240 For that you need find It's a bit more complex, 308 00:15:05.320 --> 00:15:09.440 but extremely powerful. You can search for files based on name, yes, 309 00:15:09.559 --> 00:15:14.559 but also size, modification, time, permissions, owner, almost any attribute 310 00:15:14.559 --> 00:15:16.600 you can think of. It's like a database query tool 311 00:15:16.679 --> 00:15:17.559 for your file system. 312 00:15:17.720 --> 00:15:21.399 Got it? All these tools manage the system as it is. Yeah, 313 00:15:21.440 --> 00:15:25.399 but what about installing new software, updating things, removing old stuff? 314 00:15:25.559 --> 00:15:26.399 Package management? 315 00:15:26.559 --> 00:15:28.799 Yeah, that's crucial and it used to be painful. 316 00:15:28.960 --> 00:15:30.440 Dependency hell, exactly. 317 00:15:31.039 --> 00:15:33.919 The sources mentioned early systems like RPM, you'd try to 318 00:15:33.960 --> 00:15:37.120 install something and it would say needs library X. So 319 00:15:37.159 --> 00:15:38.960 you'd find library X, try to install it and it 320 00:15:39.000 --> 00:15:41.399 would say needs library Y version two, but you have 321 00:15:41.519 --> 00:15:43.000 version one. It was a nightmare. 322 00:15:43.080 --> 00:15:43.720 Sounds awful. 323 00:15:43.879 --> 00:15:46.919 It was, but modern package managers like DNF, which is 324 00:15:46.960 --> 00:15:50.600 common now, have mostly solved this. They handle dependencies automatically. 325 00:15:50.759 --> 00:15:54.519 You say install package Z, and DNF figures out everything 326 00:15:54.559 --> 00:15:57.639 else Z needs, fetches it all and installs it in 327 00:15:57.679 --> 00:16:01.279 the right order. It does updates, removal, handles conflicts. It 328 00:16:01.320 --> 00:16:02.879 makes life so much easier. 329 00:16:02.919 --> 00:16:04.440 That's a huge improvement. 330 00:16:04.159 --> 00:16:08.360 Massive, And DNF is smart enough to keep multiple kernels installed. 331 00:16:08.840 --> 00:16:11.159 Ah. You mentioned that for recovery. 332 00:16:10.799 --> 00:16:15.159 Right, If a kernel update causes boot problems, the bootloader 333 00:16:15.279 --> 00:16:19.519 grub usually lets you select an older working kernel. It's 334 00:16:19.519 --> 00:16:22.480 a built in safety net provided by the package management system. 335 00:16:22.559 --> 00:16:26.440 Makes sense, and clearly, all these skills monitoring, file handling, 336 00:16:26.519 --> 00:16:30.360 package management, they aren't just for emergencies, not at all. 337 00:16:30.440 --> 00:16:34.279 This is the daily toolkit for anyone working seriously with Linux. 338 00:16:34.399 --> 00:16:37.639 Right, so we've seen the tools, the philosophy. Let's trace 339 00:16:37.679 --> 00:16:39.879 the actual journey of a Linux system. Yeah, from hitting 340 00:16:39.879 --> 00:16:42.480 the power button to being ready to use. Understand that 341 00:16:42.559 --> 00:16:44.039 whole boot process seems key. 342 00:16:44.279 --> 00:16:47.080 It really is. Knowing what happens when DUA can be 343 00:16:47.159 --> 00:16:50.600 crucial for troubleshooting. The sources break it down into three 344 00:16:50.679 --> 00:16:51.360 main phases. 345 00:16:51.480 --> 00:16:53.279 Okay, Phase one hardware boot. 346 00:16:53.759 --> 00:16:57.639 This is your computer's basic firmware, the BIOS or the 347 00:16:57.720 --> 00:17:01.600 newer UA FI doing its power on se heelf, test PST, 348 00:17:02.120 --> 00:17:04.640 checking memory, initializing basic. 349 00:17:04.319 --> 00:17:06.960 Hardware, standard stuff for any computer pretty much. 350 00:17:07.480 --> 00:17:11.519 Then comes Phase two, the Linux boot. This is where 351 00:17:11.640 --> 00:17:13.039 GRUP usually takes. 352 00:17:12.759 --> 00:17:14.559 Over the grain unified bootloader. 353 00:17:14.640 --> 00:17:17.960 That's the one gr Read's job is to find and 354 00:17:18.039 --> 00:17:21.319 load the Linux kernel itself into memory. It does this 355 00:17:21.400 --> 00:17:25.079 in stages. Stage one is tiny, usually in the master 356 00:17:25.160 --> 00:17:27.440 boot record of the disc MBR. Then it loads a 357 00:17:27.519 --> 00:17:30.759 slightly bigger stage one point five to understand filesystems. Then 358 00:17:30.799 --> 00:17:33.799 the main stage two, which presents the menu, loads the 359 00:17:33.880 --> 00:17:37.119 chosen kernel and an initial RAM disc image called insured 360 00:17:37.200 --> 00:17:37.880 or any trams. 361 00:17:38.079 --> 00:17:41.039 And that grub menu is where you can choose older kernels. 362 00:17:40.720 --> 00:17:43.599 Of needed exactly. That's a critical function of GRRP during 363 00:17:43.640 --> 00:17:44.720 the Linux boot phase. 364 00:17:44.759 --> 00:17:45.759 Okay, kernels loaded. 365 00:17:45.920 --> 00:17:48.680 Phase three Linux startup. Now the kernel is running, but 366 00:17:48.720 --> 00:17:50.400 it needs to start everything else. This is where the 367 00:17:50.400 --> 00:17:53.039 innit system comes in. Historically this was simpler, but now 368 00:17:53.039 --> 00:17:54.160 it's usually systems. 369 00:17:53.880 --> 00:17:55.039 System seems to be everywhere. 370 00:17:55.079 --> 00:17:59.359 Now it is. It's powerful but complex. System is responsible 371 00:17:59.400 --> 00:18:02.920 for starting all the background services, mounting file systems setting 372 00:18:03.000 --> 00:18:07.319 up networking basically preparing the entire host system for you 373 00:18:07.359 --> 00:18:08.200 to log in and use. 374 00:18:08.480 --> 00:18:10.880 And system decides if you get a graphical log in 375 00:18:11.039 --> 00:18:12.559 or just a text console. Yeah. 376 00:18:12.680 --> 00:18:14.759 It uses something called a default dot target. 377 00:18:14.880 --> 00:18:15.119 Yeah. 378 00:18:15.119 --> 00:18:17.680 One target might be graphical dot target, which brings up 379 00:18:17.680 --> 00:18:21.279 the whole desktop environment. Another might be multi user dot target, 380 00:18:21.319 --> 00:18:23.000 which just gives you text consoles. 381 00:18:23.119 --> 00:18:25.039 Okay, and one system has done its thing. 382 00:18:25.200 --> 00:18:28.839 If you're booting graphically, a display manager like GDM for 383 00:18:29.039 --> 00:18:32.480 Genome or SDDM for a KDE or light DM takes over, 384 00:18:32.880 --> 00:18:34.119 showing you the login screen. 385 00:18:34.279 --> 00:18:34.400 Right. 386 00:18:34.519 --> 00:18:37.720 If you're in text mode, you'll interact with aged, which 387 00:18:37.799 --> 00:18:41.119 manages logins on the virtual consoles. It's cyclical. It waits 388 00:18:41.119 --> 00:18:43.559 for a username, runs log in, and when you log out, 389 00:18:43.599 --> 00:18:45.599 it starts over waiting for the next user. 390 00:18:45.720 --> 00:18:47.839 Makes sense. So now the system's up. You log in 391 00:18:48.319 --> 00:18:50.799 and you land in your shell, which needs its own. 392 00:18:50.680 --> 00:18:54.480 Configuration exactly, And there's a hierarchy here. System Wide settings 393 00:18:54.480 --> 00:18:57.400 that affect everyone are often in etceter profile or files 394 00:18:57.400 --> 00:18:58.559 in etceterprofile dot. 395 00:18:58.440 --> 00:18:59.960 D okay for all users. 396 00:19:00.279 --> 00:19:03.319 Then you have your personal configuration files in your home directory, 397 00:19:03.720 --> 00:19:10.160 like bash profile for login shells or bash arch for interactive, 398 00:19:10.279 --> 00:19:12.720 non log in shells, like when you open a terminal window. 399 00:19:12.880 --> 00:19:15.119 Bash arts are the one most people edit right often. 400 00:19:15.240 --> 00:19:18.319 Yeah, for things like setting environment variables. Path is a 401 00:19:18.400 --> 00:19:18.880