WEBVTT 1 00:00:00.080 --> 00:00:03.160 Welcome back to the deep dive. Today, we're jumping into 2 00:00:03.240 --> 00:00:07.480 something really essential, getting a handle on red Hat Enterprise 3 00:00:07.559 --> 00:00:13.160 Lenox nine rh A nine. We're basically mining the Enterprise 4 00:00:13.240 --> 00:00:16.839 Lenox nine Certification Study Guide, the RHGSA one from twenty 5 00:00:16.879 --> 00:00:18.839 twenty four for the absolute core stuff. 6 00:00:18.920 --> 00:00:21.199 Exactly. The mission really is to pull out those key 7 00:00:21.280 --> 00:00:24.679 ideas about RHGL nine administration, make it clear maybe even 8 00:00:24.760 --> 00:00:27.800 you know, engaging, avoid just drowning you in information. 9 00:00:28.079 --> 00:00:30.440 Yeah, think of it as a shortcut. We're not replacing 10 00:00:30.440 --> 00:00:32.399 the guide obviously, No, no, definitely not. 11 00:00:32.679 --> 00:00:35.320 But it's like a focused look at the must nose. 12 00:00:36.119 --> 00:00:39.359 So whether you're just kind of RHL curious or you're 13 00:00:39.359 --> 00:00:41.000 actually you know, needing to work with. 14 00:00:40.920 --> 00:00:42.960 It, right, we hope this helps you nail down those 15 00:00:43.000 --> 00:00:46.320 fundamentals and maybe you uncover a few surprising bits along 16 00:00:46.320 --> 00:00:48.840 the way. So useful. Okay, let's kick off part one, 17 00:00:49.759 --> 00:00:52.479 getting started setting things up, and then the command line itself. 18 00:00:53.039 --> 00:00:58.359 So groundwork first, hardware. Now, the actual RHCSA exam. It 19 00:00:58.439 --> 00:00:59.880 doesn't test hardware. 20 00:00:59.520 --> 00:01:02.000 Knowledge, but you need something to run it on, obviously, 21 00:01:02.560 --> 00:01:03.479 Exactly it. 22 00:01:03.399 --> 00:01:04.840 Has to be a six to four bit system. That's 23 00:01:04.879 --> 00:01:09.200 a must. And if you're using virtual machines for practice, which, 24 00:01:09.519 --> 00:01:11.760 let's be honest, is probably how most people learn this stuff. 25 00:01:11.840 --> 00:01:13.159 Yeah, highly recommended. 26 00:01:13.799 --> 00:01:17.920 The guide suggests aiming for at least eight GB of RAM. 27 00:01:18.959 --> 00:01:21.680 That's if you want to run a couple of vms comfortably, right, like. 28 00:01:21.640 --> 00:01:25.079 A server and maybe a client, or just two practice machines. 29 00:01:25.239 --> 00:01:29.920 It mentions VMware workstation players specifically, which is a solid choice. 30 00:01:29.959 --> 00:01:32.680 Yeah, but KVM is another great one, especially if you're 31 00:01:32.680 --> 00:01:34.480 already comfortable in a Linux environment. 32 00:01:34.879 --> 00:01:37.599 They're just different ways to get that virtual sandbox set up, 33 00:01:37.719 --> 00:01:37.920 you know. 34 00:01:38.079 --> 00:01:40.560 Yeah, and having that good practice setup is key. It 35 00:01:40.640 --> 00:01:42.840 just avoids a lot of frustration down the line if 36 00:01:42.879 --> 00:01:44.879 your base system can actually handle it. 37 00:01:45.040 --> 00:01:49.159 Okay, so installation itself. You've got your boot, media, DBD, maybe. 38 00:01:49.079 --> 00:01:51.000 USB, uh huh, the usual suspects. 39 00:01:51.079 --> 00:01:54.640 Then you hit partitioning. This is where you're dividing up 40 00:01:54.680 --> 00:01:55.319 your disc. 41 00:01:55.319 --> 00:01:57.760 Think of it like setting up drawers in a filing 42 00:01:57.799 --> 00:02:01.439 cabinet before you put files in. Create the partitions, assign 43 00:02:01.599 --> 00:02:05.359 mount points like the main slash for the root directory 44 00:02:05.599 --> 00:02:09.280 or home for user files exactly, and the way richil 45 00:02:09.400 --> 00:02:14.159 nine organizes files within those partitions. The default file system 46 00:02:14.560 --> 00:02:17.120 is excess. That gets the main focus in. 47 00:02:17.080 --> 00:02:19.439 The guide, right, So you set up your partitions, choose 48 00:02:19.439 --> 00:02:24.919 your software, and for learning, the guide points towards server 49 00:02:25.120 --> 00:02:26.159 with uy. Yeah. 50 00:02:26.199 --> 00:02:28.520 That gives you both the command line and a graphical desktop, 51 00:02:28.520 --> 00:02:30.120 which can be handy when you're starting. 52 00:02:30.199 --> 00:02:32.840 You set the root passwords super important, that's the master key. 53 00:02:32.919 --> 00:02:34.400 Don't lose that, huh. 54 00:02:34.520 --> 00:02:37.039 Yeah, and then there's a little initial setup after the 55 00:02:37.039 --> 00:02:37.599 first boot. 56 00:02:37.800 --> 00:02:38.919 Pretty straightforward stuff. 57 00:02:38.919 --> 00:02:41.439 Okay, So you're logged in now the command line that's 58 00:02:41.439 --> 00:02:42.120 where the action. 59 00:02:42.039 --> 00:02:44.280 Is pretty much, and the default language the shell you're 60 00:02:44.280 --> 00:02:45.080 talking to is. 61 00:02:45.280 --> 00:02:47.280 Bash, right BSh. Yeah. 62 00:02:47.319 --> 00:02:50.840 There are others like KSh, tcs ZISH, yeah, you might 63 00:02:50.840 --> 00:02:53.800 see them, but Bash is the default you'll find yourself in. 64 00:02:54.039 --> 00:02:57.800 You can have multiple command lines open these virtual consoles. 65 00:02:57.360 --> 00:02:59.439 Oh yeah, like having different text based screens. You can 66 00:02:59.479 --> 00:03:02.759 flip between them seatrawl alt F three, seatrawl alt f four, 67 00:03:02.840 --> 00:03:04.680 things like that. Each one can be a separate log 68 00:03:04.680 --> 00:03:05.120 in session. 69 00:03:05.360 --> 00:03:09.479 Handy. Okay, course skills finding your way around. 70 00:03:09.360 --> 00:03:14.039 First up PWD print working directory tells you where you 71 00:03:14.039 --> 00:03:14.879 are right now. 72 00:03:14.719 --> 00:03:17.759 And CD to move change directory. 73 00:03:17.439 --> 00:03:21.000 Exactly, and you need to get the difference between absolute paths. 74 00:03:21.039 --> 00:03:22.639 Starting from the root like a full. 75 00:03:22.479 --> 00:03:23.879 Address all major documents. 76 00:03:24.039 --> 00:03:27.120 Yeah, and relative paths which are based on your current location, 77 00:03:27.280 --> 00:03:30.479 like go up one level CD, or go into this 78 00:03:30.639 --> 00:03:32.520 directory here's CD, durnet, we. 79 00:03:32.520 --> 00:03:36.039 Got it, and this path variable ah path. 80 00:03:36.159 --> 00:03:38.680 That's basically a list of directories the system checks whenever 81 00:03:38.719 --> 00:03:41.520 you just type of command name like l's or p doud. 82 00:03:41.879 --> 00:03:42.960 It's how it finds the program. 83 00:03:43.039 --> 00:03:44.800 Okay, and the tilled. 84 00:03:44.879 --> 00:03:47.319 Oh, the tildy that's just a shortcut always takes you 85 00:03:47.360 --> 00:03:49.560 back to your own home directory. Super useful. 86 00:03:49.680 --> 00:03:52.639 Nice okay. Dealing with files and directories. 87 00:03:52.479 --> 00:03:56.199 Listing them l's that's your basic listing command, but the 88 00:03:56.199 --> 00:03:57.919 real power is in the options like. 89 00:03:57.919 --> 00:04:02.439 Aero for the long listing, shows missions, size, date, right. 90 00:04:02.560 --> 00:04:05.479 And a to see all files, including the hidden ones 91 00:04:05.520 --> 00:04:07.960 that start with a dot. Then you've got at to 92 00:04:08.000 --> 00:04:10.080 sort by time. It shows the inn number like a 93 00:04:10.159 --> 00:04:12.639 unique id for the file on the disc. R R 94 00:04:12.759 --> 00:04:16.800 reverses the sort order, and MSR capital r that lists 95 00:04:16.959 --> 00:04:20.000 everything recursively like all the subdirectories too. 96 00:04:20.199 --> 00:04:20.519 Wow. 97 00:04:20.680 --> 00:04:23.120 Okay, so l's is pretty powerful. 98 00:04:23.319 --> 00:04:27.600 Definitely worth learning those options. Creating directories mm deer make 99 00:04:27.639 --> 00:04:29.720 directory and the optic option is great. It creates parent 100 00:04:29.720 --> 00:04:34.160 directories if they don't already exist. So mm ear MmpD one, 101 00:04:34.360 --> 00:04:37.120 deer two, deer three works even if deer one and 102 00:04:37.199 --> 00:04:38.319 deer two aren't there yet. 103 00:04:38.360 --> 00:04:40.199 Saves time and empty files. 104 00:04:40.360 --> 00:04:43.079 Touch just touch file name, or you can update the 105 00:04:43.079 --> 00:04:44.639 timestamp of an existing file. 106 00:04:44.439 --> 00:04:46.959 With it too. Okay, Copying, moving, removing. 107 00:04:46.879 --> 00:04:50.480 CP for copy, MV for move, which also renames files 108 00:04:50.480 --> 00:04:52.639 by the way, and RM for remove. 109 00:04:52.959 --> 00:04:55.079 And this is the one to be careful with, right, No. 110 00:04:55.120 --> 00:04:58.439 Trash bin exactly. Once you arm something, it's generally gone. 111 00:04:58.480 --> 00:05:00.399 So yeah, double check before you hit enter. 112 00:05:00.639 --> 00:05:03.480 Good advice. What about links? Hard link soft links? 113 00:05:03.639 --> 00:05:06.800 Right, So MMn file name link name creates a hard link. 114 00:05:07.199 --> 00:05:09.959 Think of it as two directory entries pointing to the 115 00:05:10.000 --> 00:05:12.480 exact same data block on the disc. If you delete 116 00:05:12.519 --> 00:05:14.759 one name, the data is still there under the other name. 117 00:05:15.040 --> 00:05:19.319 Soft links or symbolic links are made with LNNSS. That's 118 00:05:19.360 --> 00:05:21.360 more like a shortcut. It just points to the name 119 00:05:21.360 --> 00:05:23.480 of the original file. If the original file moves or 120 00:05:23.519 --> 00:05:25.040 gets deleted, the soft link breaks. 121 00:05:25.399 --> 00:05:27.639 Gotcha. So hard links point to the data. Soft links 122 00:05:27.639 --> 00:05:28.240 point to the name. 123 00:05:28.319 --> 00:05:28.800 Pretty much. 124 00:05:28.879 --> 00:05:30.959 Yeah, all right, permissions, This looks important. 125 00:05:31.439 --> 00:05:36.079 Chwud very important schmad changes the mode the permissions. You 126 00:05:36.079 --> 00:05:38.560 can use numbers like schmod six forty file. 127 00:05:38.480 --> 00:05:40.279 Six four zero. What does that mean? 128 00:05:40.360 --> 00:05:44.319 It's octal. Each number represents permissions for user, group and others. 129 00:05:44.639 --> 00:05:47.160 Six is read and write, four plus two four is 130 00:05:47.199 --> 00:05:49.199 read only. Zero is no permissions. 131 00:05:49.279 --> 00:05:51.600 Ah. Okay, r as four w is two. 132 00:05:51.639 --> 00:05:54.399 X is one exactly. Or you can use the symbolic 133 00:05:54.480 --> 00:05:58.279 mode you gore x like schmod g plus w file 134 00:05:58.399 --> 00:06:01.160 adds right permission for the group g com for user 135 00:06:01.199 --> 00:06:02.160 G group oh others. 136 00:06:02.240 --> 00:06:04.800 Okay, that seems more intuitive, Maybe it can be. 137 00:06:04.879 --> 00:06:09.319 The guide also mentions special dits sgid G plus s 138 00:06:09.399 --> 00:06:12.480 on a director means new files created inside it get 139 00:06:12.519 --> 00:06:15.920 the directory's group, not the user's primary group, and the 140 00:06:15.959 --> 00:06:20.079 sticky bit O plus T on a shared directory like 141 00:06:20.160 --> 00:06:23.079 tm tem it means only the owner of a file 142 00:06:23.120 --> 00:06:25.839 can delete it, even if others have right permission to 143 00:06:25.839 --> 00:06:26.439 the directory. 144 00:06:26.720 --> 00:06:28.600 Ah. Useful for shared spaces. 145 00:06:28.680 --> 00:06:32.480 Yeah. Then chound changes the owner th hg RP changes 146 00:06:32.519 --> 00:06:37.319 the group pretty straightforward, and the ooh mask that sets 147 00:06:37.360 --> 00:06:40.879 the default permissions. When you create a new file or directory, 148 00:06:41.199 --> 00:06:44.399 the system starts with full permissions and then subtracts whatever 149 00:06:44.480 --> 00:06:47.959 the mask specifies, so it controls how things are created initially. 150 00:06:48.040 --> 00:06:50.360 Okay, kind of like a template for new file permissions 151 00:06:50.399 --> 00:06:50.720 sort of. 152 00:06:50.800 --> 00:06:52.759 Yeah, it masks off permissions. 153 00:06:52.759 --> 00:06:54.279 Then chatter file attributes. 154 00:06:54.399 --> 00:06:57.040 Yeah, that's another layer chatter. Let's you say, attributes like 155 00:06:57.079 --> 00:07:00.759 immutable plus I. If a file is immutable, nobody can 156 00:07:00.839 --> 00:07:02.519 change or delete it, not even root. 157 00:07:02.639 --> 00:07:03.839 Seriously, not even root. 158 00:07:03.920 --> 00:07:06.480 Nope, you have to remove the immutable flag first. With 159 00:07:06.600 --> 00:07:09.720 chat r, there's also a pend only plus a where 160 00:07:09.720 --> 00:07:11.240 you can add to the end of a file but 161 00:07:11.279 --> 00:07:13.240 can't delete or change existing content. 162 00:07:13.439 --> 00:07:16.920 Interesting, okay. Working with text dot redirection super useful. 163 00:07:17.360 --> 00:07:21.600 The greater then sign redirects output to a file overwriting 164 00:07:21.639 --> 00:07:25.319 it double greater than a pens to the file. Less 165 00:07:25.360 --> 00:07:28.079 then feeds a file as input to a command, and 166 00:07:28.120 --> 00:07:30.959 the pipe sends the output of one command directly as 167 00:07:31.040 --> 00:07:31.519 input to. 168 00:07:31.439 --> 00:07:33.680 The next, Say chaining commands together. 169 00:07:33.439 --> 00:07:35.839 Exactly and two redirects error messages. 170 00:07:35.839 --> 00:07:39.560 Specifically, good to know searching text dot rep rep. 171 00:07:39.360 --> 00:07:43.519 Is your best friend for searching dot GP pattern file name, 172 00:07:43.920 --> 00:07:47.199 and it gets really powerful with regular expressions. Those special 173 00:07:47.279 --> 00:07:51.240 characters like dot for any character, square brackets for set 174 00:07:51.240 --> 00:07:56.079 of characters, question mark plus plus star for matching repetitions. 175 00:07:56.240 --> 00:07:58.120 Let's you do really complex pattern matching. 176 00:07:58.439 --> 00:08:00.680 Absolutely, and if you just need to compare two files, 177 00:08:00.720 --> 00:08:02.639 see what's different, use diff. 178 00:08:02.759 --> 00:08:06.240 Defall one file two simple enough YEP editing files. Okay, VI, 179 00:08:06.720 --> 00:08:07.879 this one has a reputation. 180 00:08:08.040 --> 00:08:10.160 It does, it's powerful, it's everywhere. But yeah, it had 181 00:08:10.199 --> 00:08:13.000 a learning curve. The key is understanding its modes, especially 182 00:08:13.040 --> 00:08:13.639 command mode. 183 00:08:13.720 --> 00:08:16.120 Right, we're not typing text directly exactly. 184 00:08:16.160 --> 00:08:19.360 You use keys like to search forward, to search backward right, 185 00:08:19.480 --> 00:08:23.560 followed by commands like W to wright, save, q to quit, 186 00:08:23.920 --> 00:08:25.600 or to buq to save and quit. 187 00:08:25.800 --> 00:08:30.240 Okay. And these special versions VBO, VG pseudo. 188 00:08:29.920 --> 00:08:34.440 Ah, yeah, those are wrappers around V, specifically for editing 189 00:08:34.440 --> 00:08:37.320 critical system files like et cetubas, food, et cetera, group 190 00:08:37.360 --> 00:08:40.879 and etcetera. Pseudos they add safeguards like file locking to 191 00:08:40.919 --> 00:08:43.759 prevent multiple people editing at once or messing things up 192 00:08:43.799 --> 00:08:47.480 too badly. Definitely use those when editing those specific files. 193 00:08:47.559 --> 00:08:50.759 But if V is just too much at first, well, 194 00:08:50.799 --> 00:08:53.000 you can actually change your default editor. You set the 195 00:08:53.080 --> 00:08:56.480 editor environment variable and the guide mentions NANO, which is 196 00:08:56.600 --> 00:08:59.559 much simpler and more like a standard notepad style editor, 197 00:09:00.000 --> 00:09:02.200 and you at the bottom pretty intuitive. 198 00:09:01.799 --> 00:09:04.519 Good alternative to know about definitely. Lastly, for this section, 199 00:09:04.600 --> 00:09:07.279 getting help documentation crucial. 200 00:09:07.480 --> 00:09:10.120 Man pages are the first stop man command name read 201 00:09:10.159 --> 00:09:10.679 the manual. 202 00:09:10.799 --> 00:09:11.840 People always say that. 203 00:09:11.799 --> 00:09:14.679 Because it's true, especially check the example section at the 204 00:09:14.720 --> 00:09:16.519 end of many men pages. Super helpful. 205 00:09:16.559 --> 00:09:17.799 Okay, what is an apropos? 206 00:09:18.080 --> 00:09:20.159 What shared as gives you just a quick one line 207 00:09:20.159 --> 00:09:23.799 summary of what a command does. Apropos keyword searches those summaries, 208 00:09:23.799 --> 00:09:25.519 so if you can't remember the command name but know 209 00:09:25.600 --> 00:09:27.399 what it does, apropos can help you find it. 210 00:09:27.639 --> 00:09:33.080 Nice and infodocs oser doc Info is another documentation system, 211 00:09:33.320 --> 00:09:35.919 sometimes more detailed than man pages, but maybe less used 212 00:09:35.960 --> 00:09:39.879 now and yeah, asha doc often has rehabiens examples, extra 213 00:09:39.919 --> 00:09:42.919 docs provided by the software package itself always worth a look. 214 00:09:42.919 --> 00:09:43.799 If you're stuck. 215 00:09:44.039 --> 00:09:46.600 Lots of places to find help, then for sure. Okay, 216 00:09:46.679 --> 00:09:51.600 let's shift gears part two, Managing the system itself. Starting 217 00:09:51.600 --> 00:09:52.759 with software right. 218 00:09:52.919 --> 00:09:56.679 So RHL uses RPM packages. That's the underlying format, But 219 00:09:56.759 --> 00:10:00.240 the main tool you'll use to install, update remove software 220 00:10:00.279 --> 00:10:00.919 is DNF. 221 00:10:01.080 --> 00:10:03.200 DNF okay you replace YM right. 222 00:10:03.279 --> 00:10:06.480 Yeah. DNF is the modern version. It talks to repositories 223 00:10:06.519 --> 00:10:09.879 basically online collections of software packages. These are configured in 224 00:10:09.919 --> 00:10:12.600 files under ETCM, DOT Repo, dot D and. 225 00:10:12.679 --> 00:10:14.200 Red Hat subscription management. 226 00:10:14.320 --> 00:10:16.679 That's how your system proves it's allowed to access the 227 00:10:16.720 --> 00:10:20.000 official red Hat repositories and get updates in software. And 228 00:10:20.120 --> 00:10:22.960 DNF handles dependencies automatically. 229 00:10:22.559 --> 00:10:25.320 Meaning if you install program A and needs library B 230 00:10:25.440 --> 00:10:28.200 to work, DNF figures that out and installs library B 231 00:10:28.240 --> 00:10:29.080 too exactly. 232 00:10:29.159 --> 00:10:29.879 Saves a ton of. 233 00:10:29.840 --> 00:10:31.679 Hassle so common DNF commands. 234 00:10:31.759 --> 00:10:36.200 DNF List shows available or installed packages. DNF install package name, 235 00:10:36.440 --> 00:10:41.960 DNF update updates everything or just one package. DNF remove package. 236 00:10:41.639 --> 00:10:43.960 Name, okay, install update, remove what else. 237 00:10:44.039 --> 00:10:46.799 DNF info package name gives you details about a package. 238 00:10:47.039 --> 00:10:51.279 DNF repolist shows you which repositories your system is actually using, 239 00:10:51.679 --> 00:10:54.039 and DNF provides file name as useful, it tells you 240 00:10:54.159 --> 00:10:57.159 which package owns a specific file like a SERB and. 241 00:10:57.200 --> 00:10:59.240 Mash ah handy for tracking things down. 242 00:10:59.519 --> 00:11:01.639 And While DNF is the main tool, you can sometimes 243 00:11:01.679 --> 00:11:03.200 interact with RPM files. 244 00:11:02.919 --> 00:11:05.000 Directly using the RPM command. 245 00:11:04.759 --> 00:11:09.200 Right rpmdshis package dot RPM installs a specific RPM file, 246 00:11:09.279 --> 00:11:12.679 I install viver bose h hash marks for progress. RPM 247 00:11:12.759 --> 00:11:16.600 dosh qa lists all installed packages, rpmdsh QL package name 248 00:11:16.639 --> 00:11:19.360 lists all the files inside and installed package okay, and 249 00:11:19.519 --> 00:11:22.919 RPM dash K package dot RPM verifies the package's digital 250 00:11:22.960 --> 00:11:27.159 signature using gpgkeys usually stored in et cetera, KERPM, DOUSHDPG 251 00:11:27.440 --> 00:11:29.559 to make sure it's legitimate and hasn't been tampered with. 252 00:11:29.840 --> 00:11:34.720 Security check good. What about module streams ah modules? 253 00:11:35.240 --> 00:11:38.600 There a way? Our HL offers different versions of software 254 00:11:38.639 --> 00:11:41.120 like maybe Python three point nine and Python three point 255 00:11:41.200 --> 00:11:44.639 one one on the same system without conflicts. You can 256 00:11:44.720 --> 00:11:48.840 use DNF module list and DNF module infotasy what's available? Okay. 257 00:11:48.840 --> 00:11:53.240 It provides flexibility exactly right. System startup the boot process. 258 00:11:53.279 --> 00:11:54.080 How does that work? 259 00:11:54.399 --> 00:11:58.159 It's a sequence. First, the bios or UA five firmware 260 00:11:58.279 --> 00:12:01.840 initializes the hardware. Then and it hands off to the bootloader. 261 00:12:01.360 --> 00:12:04.200 Which is GRB two and RHL nine correct. 262 00:12:04.519 --> 00:12:07.600 GRB two then loads the Linux kernel into memory. The 263 00:12:07.679 --> 00:12:11.120 kernel starts up, mounts a temporary initial filesystem called the 264 00:12:11.159 --> 00:12:14.480 INNA tramps, and finally the kernel starts the very first 265 00:12:14.559 --> 00:12:18.480 real process, which is systemed. System gets process ID one 266 00:12:18.600 --> 00:12:21.039 and it takes over managing the rest of the system. 267 00:12:21.080 --> 00:12:22.720 Startup system does the big boss. 268 00:12:22.759 --> 00:12:25.600 Then pretty much the conductor, As the guide. 269 00:12:25.320 --> 00:12:27.919 Says, what about GRB two itself? Anything we need to know? 270 00:12:28.159 --> 00:12:30.159 You'll see its menu at boot. You can choose different 271 00:12:30.200 --> 00:12:33.279 kernels if you have them. Pressing E lets you temporarily 272 00:12:33.480 --> 00:12:37.159 edit the kernel boot parameters useful for troubleshooting. Sometimes its 273 00:12:37.200 --> 00:12:41.200 main config file is etc default grub a key setting. 274 00:12:41.200 --> 00:12:43.679 There is jur rub time out how long the menu 275 00:12:43.679 --> 00:12:45.720 waits before booting the default entry? 276 00:12:45.879 --> 00:12:48.399 Right. So, systemed you said it manages everything. 277 00:12:48.600 --> 00:12:53.440 It manages services, devices, mount points, almost everything using units. 278 00:12:53.720 --> 00:12:56.200 These are just configuration files telling a system to how 279 00:12:56.200 --> 00:12:56.960 to manage something. 280 00:12:57.200 --> 00:12:58.360 Where are these unit files? 281 00:12:58.440 --> 00:13:01.480 System Wide defaults are in e U solob systemed system 282 00:13:01.679 --> 00:13:05.039 and your customizations or locally installed ones go in its 283 00:13:05.039 --> 00:13:09.440 systems system Targets. Targets are special units that group other units. 284 00:13:09.480 --> 00:13:11.279 Think of them like run levels in the old days. 285 00:13:11.600 --> 00:13:15.000 Multi user dot target is your typical command line server state. 286 00:13:15.360 --> 00:13:18.320 Graphical dot target adds the graphical desktop on top of that. 287 00:13:18.759 --> 00:13:20.399 How do you control these units and. 288 00:13:20.360 --> 00:13:22.840 Targets with the system's statle command? 289 00:13:23.120 --> 00:13:24.679 It's central, okay, What can I do? 290 00:13:24.960 --> 00:13:30.519 System statle start service name stop, restart, reload to reread 291 00:13:30.519 --> 00:13:33.200 config without a full restart status to see if it's 292 00:13:33.279 --> 00:13:34.639 running and get recent logs. 293 00:13:34.679 --> 00:13:37.200 Basic service control Yeah. 294 00:13:36.759 --> 00:13:39.879 Then system tell'll enable service name makes it start automatically 295 00:13:39.919 --> 00:13:44.000 at boot disabled, stops that is enabled, checks the current setting, 296 00:13:44.240 --> 00:13:48.159 and list units shows everything system is currently managing. 297 00:13:48.519 --> 00:13:51.240 Can you change the default state like boot to command 298 00:13:51.320 --> 00:13:52.799 line instead of graphical Yep. 299 00:13:52.919 --> 00:13:56.120 You can set the default target using system teleset default. 300 00:13:56.200 --> 00:13:59.399 Okay, what if things go wrong during boot? How do 301 00:13:59.440 --> 00:14:01.200 you see messages journal? 302 00:14:01.240 --> 00:14:04.480 Telll that's the command to view the system journal, which 303 00:14:04.480 --> 00:14:06.559 collects logs from pretty much everywhere. 304 00:14:06.720 --> 00:14:08.840 So system lugs are centralized now largely. 305 00:14:08.919 --> 00:14:11.879 Yes, And for troubleshooting, you can manually boot to a 306 00:14:11.919 --> 00:14:15.240 specific target by adding like system d dot unit multi 307 00:14:15.320 --> 00:14:18.080 user dot target to the kernel line in grub. Okay, 308 00:14:18.120 --> 00:14:20.000 and there's dart dot break. You can add two, which 309 00:14:20.039 --> 00:14:22.919 interrupts the boot process very early, drops you into a shell. 310 00:14:23.360 --> 00:14:26.799 Useful for things like receiving a lost root password. Power 311 00:14:26.799 --> 00:14:30.080 for stuff can be a lifesaver. Oh and interestingly, commands 312 00:14:30.080 --> 00:14:33.480 like shut down, reboot, halt they're mostly just links pointing 313 00:14:33.519 --> 00:14:34.440 back to system. 314 00:14:34.159 --> 00:14:36.000 Techle Now, system really took over? 315 00:14:36.360 --> 00:14:39.879 It really did. And for time management, time detectal shows 316 00:14:39.879 --> 00:14:42.759 and sets the system time and time zone, and cronid 317 00:14:42.879 --> 00:14:45.240 is the service that sinks your clock over the network 318 00:14:45.320 --> 00:14:46.000 using NTP. 319 00:14:46.440 --> 00:14:48.200 Got it? Okay? Users in groups. 320 00:14:48.000 --> 00:14:50.000 Right, You generally don't want to be logged in as 321 00:14:50.080 --> 00:14:54.159 route all the time, bad practice. So you create regular 322 00:14:54.279 --> 00:14:54.960 user accounts. 323 00:14:55.120 --> 00:14:56.679 Where is user info store? 324 00:14:56.759 --> 00:15:01.639 It's mainly in Etcetera's user info etc. Shadow, Secure password info, etc. 325 00:15:01.919 --> 00:15:06.279 Group info and etcetera Shadow secure group info. Defaults for 326 00:15:06.320 --> 00:15:08.840 new users come from at clog in dot DEFs. 327 00:15:08.600 --> 00:15:10.039 And the commands to manage them. 328 00:15:10.200 --> 00:15:13.799 User AD creates a user, User MOD modifies an existing user. 329 00:15:14.200 --> 00:15:17.279 You can use options like EDES to change their shell 330 00:15:17.440 --> 00:15:21.399 AOD for home directory, DAD them to supplementary groups. User 331 00:15:21.440 --> 00:15:24.279 at deletes a user. Use ther option with user del 332 00:15:24.320 --> 00:15:25.080 to remove their. 333 00:15:24.919 --> 00:15:26.919 Home directory too important detail. 334 00:15:27.039 --> 00:15:30.639 Yeah, Password username changes the user's password. You can also 335 00:15:30.720 --> 00:15:33.240 use password batstin to pipe a password in maybe from 336 00:15:33.240 --> 00:15:36.440 a script. Password atch l username locks an account, you 337 00:15:36.679 --> 00:15:38.679 unlocks it ato E sets and expiration date. 338 00:15:38.840 --> 00:15:40.519 Lots of control their end groups plant. 339 00:15:40.320 --> 00:15:44.120 Group, AD, group, mod, group del. Simple enough. Users have 340 00:15:44.159 --> 00:15:47.559 one primary group but can be members of many supplementary groups. 341 00:15:47.840 --> 00:15:49.000 That's all defined in et cetera. 342 00:15:49.039 --> 00:15:52.200 Group. Okay, what about getting root privileges when you need them. 343 00:15:52.360 --> 00:15:54.679 Well, they're sue switch user. You can sue to become 344 00:15:54.799 --> 00:15:57.200 root if you know the root password. But the more 345 00:15:57.240 --> 00:15:59.360 common and generally better way. 346 00:15:59.240 --> 00:16:02.039 Is pseudo right super rousers do Yeah. 347 00:16:02.080 --> 00:16:05.360 It lets specific users run specific commands as route without 348 00:16:05.440 --> 00:16:08.799 needing the root password. It's configured in et ceter Suitors 349 00:16:08.879 --> 00:16:11.919 use the pseudo command to edit this safely, or by 350 00:16:11.960 --> 00:16:14.240 adding files in et cetera suters dot and. 351 00:16:14.200 --> 00:16:17.120 You can grant permissions to groups like the Wheel group exactly. 352 00:16:17.320 --> 00:16:19.440 Often admins are just added to the Wheel group and 353 00:16:19.480 --> 00:16:22.320 that group is given pseudo access in the configuration. You 354 00:16:22.360 --> 00:16:25.279 can also allow passwordless pseudo for certain commands with the 355 00:16:25.519 --> 00:16:27.600 no pay SSWD tag okay. 356 00:16:27.639 --> 00:16:31.080 Flexible user environment files like Bash RCI. 357 00:16:31.080 --> 00:16:33.720 Yeah, those control your shell environment, et Cetera profile and 358 00:16:33.799 --> 00:16:37.120 etceterashard are system wide. Then each user has their own 359 00:16:37.200 --> 00:16:40.879 Bash profile for login shells and augershar for interactive shells. 360 00:16:41.399 --> 00:16:44.480 There's also etceeter profile dot d, which contains scripts run 361 00:16:44.480 --> 00:16:48.039 at log in good place for system wide customizations. 362 00:16:47.519 --> 00:16:50.840 Setting aliases, environment variables, that kind of thing exactly, okay, 363 00:16:50.879 --> 00:16:53.039 storty deep dive partitions again. 364 00:16:53.240 --> 00:16:56.360 Tools you've got f disc, which is older works well 365 00:16:56.360 --> 00:16:59.200 for MBR discs. Then gie disc is for modern GPT 366 00:16:59.440 --> 00:17:03.000 partition discs, and parted is another powerful tool works with 367 00:17:03.080 --> 00:17:05.880 Both can be used interactively or scripted. 368 00:17:06.039 --> 00:17:06.960 What can you do with them? 369 00:17:07.200 --> 00:17:11.200 The basics Print the partition table, P create new partitions 370 00:17:11.240 --> 00:17:14.839 and delete them D change the partition type to use 371 00:17:14.960 --> 00:17:17.240 LDC the type codes like a E for Linux, LBM 372 00:17:17.599 --> 00:17:21.279 eighty two for swap, write changes to disc w or 373 00:17:21.400 --> 00:17:22.319 quit without saving Q. 374 00:17:22.839 --> 00:17:25.000 And you mentioned needing to tell the kernel about changes. 375 00:17:25.200 --> 00:17:28.799 Yes, crucial step after using f disc or g disc 376 00:17:28.960 --> 00:17:31.640 or parted to change partitions on a disc that's in use, 377 00:17:31.839 --> 00:17:34.599 the kunnel might not see the changes. Immediately, run part 378 00:17:34.640 --> 00:17:37.079 probe to ask the kernel to reread the partition table 379 00:17:37.319 --> 00:17:38.000 or just reboot. 380 00:17:38.039 --> 00:17:40.039 Okay, reboot, got it. Formatting. 381 00:17:40.160 --> 00:17:44.039 Once you have a partition, you need a filesystem. Use mkfs, 382 00:17:44.200 --> 00:17:47.119 mkfs dot, XFS dev's day one formats that partition with 383 00:17:47.279 --> 00:17:50.720 XFS or mkfs dot, ext fours dB two for. 384 00:17:50.839 --> 00:17:53.160 EXT four and mounting making it usable. 385 00:17:53.480 --> 00:17:56.960 Right, you mount the filesystem onto a directory a mount point. 386 00:17:57.160 --> 00:17:59.400 For permanent mounts that happen at boot, you can figure 387 00:17:59.440 --> 00:18:00.480 them in etcetera. 388 00:18:00.559 --> 00:18:01.480 Snet what's in there? 389 00:18:01.519 --> 00:18:04.680 Each line defines a mount the device, often by UUID, 390 00:18:05.079 --> 00:18:08.319 the mount point directory, the filesystem type like x SpaceX 391 00:18:08.319 --> 00:18:11.079 to four, NFS mount options, and then two numbers for 392 00:18:11.119 --> 00:18:13.319 backup dump and filesystem check. 393 00:18:13.240 --> 00:18:16.720 Order pass okay, and you find the UIDs with ball kid. 394 00:18:17.119 --> 00:18:20.480 Great command shows uoids and filesystem types for all your 395 00:18:20.519 --> 00:18:23.839 block devices. Using UIDs and haf STAB is better than 396 00:18:23.839 --> 00:18:26.160 device names like devs to one because the device names 397 00:18:26.160 --> 00:18:28.119 can sometimes change, but uaeds don't. 398 00:18:28.400 --> 00:18:30.799 Good. Tip and manual mounting. 399 00:18:30.599 --> 00:18:35.119 Mount device, mount point and mount mountpoint or device simple okay. 400 00:18:35.160 --> 00:18:38.799 Now, LVM Logical Volume Manager sounds complicated. 401 00:18:38.920 --> 00:18:41.599