WEBVTT 1 00:00:00.080 --> 00:00:02.640 The Linux command line. You know, for a lot of people, 2 00:00:02.680 --> 00:00:06.480 it's this incredibly powerful, but yeah, often intimidating gateway to 3 00:00:06.559 --> 00:00:09.400 controlling your system. You just stare at that blinking cursor 4 00:00:09.800 --> 00:00:11.560 and it feels a bit like a secret language you 5 00:00:11.560 --> 00:00:13.800 haven't quite cracked yet. But what if I told you 6 00:00:13.839 --> 00:00:16.679 that behind that initial, maybe slightly cryptic look lies some 7 00:00:16.719 --> 00:00:19.960 of the most elegant, flexible, and actually kind of fun 8 00:00:20.079 --> 00:00:24.039 aspects of Linux administration. Today we're doing a deep dive 9 00:00:24.280 --> 00:00:26.839 right into the heart of Linux the command line. We're 10 00:00:26.839 --> 00:00:29.920 going way beyond just you know, typing basic commands. We 11 00:00:29.960 --> 00:00:32.399 want to uncover those hidden gems and clever tricks that 12 00:00:32.479 --> 00:00:35.520 really transform it from just an interface into well, your 13 00:00:35.520 --> 00:00:38.000 most powerful ally. Our mission here is to give you 14 00:00:38.000 --> 00:00:40.840 a shortcut sort of to being truly well informed about 15 00:00:40.880 --> 00:00:42.960 how to wield this amazing tool. 16 00:00:43.159 --> 00:00:45.039 And we've got a great guide for this. We're drawing 17 00:00:45.039 --> 00:00:49.320 from excerpts from the LPIC one Linux Professional Institute Certification 18 00:00:49.399 --> 00:00:54.359 Study Guide. Uh. Now, this material it's designed specifically to 19 00:00:54.399 --> 00:00:59.799 help you install, operate, troubleshoot Linux systems. It's absolutely packed 20 00:00:59.799 --> 00:01:02.240 with the foundational knowledge. It's the kind of stuff that 21 00:01:02.280 --> 00:01:06.120 turns those symbols that might seem cryptic at first into clear, 22 00:01:06.519 --> 00:01:09.560 actionable insights. He gives you not just the what, but 23 00:01:09.640 --> 00:01:10.120 the why. 24 00:01:10.560 --> 00:01:14.079 So get ready for some serious aha moments, because we're 25 00:01:14.079 --> 00:01:17.400 going to try and demystify what might seem overwhelming. We 26 00:01:17.480 --> 00:01:21.640 want to equip you with practical skills that genuinely stick. Okay, 27 00:01:21.799 --> 00:01:23.799 let's unpack this. So when I first started messing around 28 00:01:23.840 --> 00:01:26.519 the lenox, I was just typing commands, you know, into 29 00:01:26.560 --> 00:01:29.200 that black screen. I'd hear terms like bash or shell, 30 00:01:29.560 --> 00:01:31.879 but honestly, it all just kind of blurred together. What 31 00:01:32.079 --> 00:01:34.359 is a shell really at its core? And why do 32 00:01:34.400 --> 00:01:36.079 we even have different ones? Is it just like a 33 00:01:36.120 --> 00:01:38.079 different look or something more fundamental. 34 00:01:38.200 --> 00:01:41.439 That's a really good question, because understanding the shell is fundamental. 35 00:01:41.840 --> 00:01:45.680 At its core, a shell is an interactive utility. Think 36 00:01:45.719 --> 00:01:48.040 of it as your direct interpreter for the system. 37 00:01:48.120 --> 00:01:49.040 Ah, the interpreter. 38 00:01:49.159 --> 00:01:51.799 Okay, yeah, let's you run programs, manage your files, supervis 39 00:01:51.879 --> 00:01:55.519 process all that just through text based commands. It's not 40 00:01:55.640 --> 00:01:58.879 just the window, it's the environment itself, and the most 41 00:01:58.920 --> 00:02:01.959 common one, the default for most Linux user accounts, the 42 00:02:02.000 --> 00:02:05.480 one you've probably bumped into, is the gene you born Againshell. 43 00:02:05.359 --> 00:02:08.000 Bash Bash, right, I hear that all the time. 44 00:02:08.240 --> 00:02:12.080 Exactly came out in nineteen eighty nine. But you're right. 45 00:02:12.120 --> 00:02:15.479 There are others like Dash, for example, the Debian Olmquish shell. 46 00:02:15.599 --> 00:02:16.439 It's smaller, it's. 47 00:02:16.360 --> 00:02:18.000 Faster, smaller and faster. 48 00:02:18.319 --> 00:02:21.879 Why well, it's often preferred for running scripts behind the 49 00:02:21.879 --> 00:02:26.000 scenes because it's more efficient. You know, fewer interactive features 50 00:02:26.039 --> 00:02:28.879 like fancy command line editing, but it gets the job 51 00:02:28.919 --> 00:02:30.080 done quickly for automation. 52 00:02:30.360 --> 00:02:32.479 Okay, so optimize for scripting. What else? 53 00:02:32.680 --> 00:02:35.800 Then there's the Z shell zish. That one combines features 54 00:02:35.840 --> 00:02:38.840 from Bash and others. It offers more advanced scripting, shared 55 00:02:38.879 --> 00:02:41.960 history across sessions which is cool, and even highly customizable 56 00:02:42.000 --> 00:02:45.360 theme proNTs. Lots of people really like z for interactive use. 57 00:02:45.639 --> 00:02:47.919 So it really is like having different ways to talk 58 00:02:47.960 --> 00:02:49.759 to your computer depending on what you need to do. 59 00:02:50.960 --> 00:02:53.919 That makes sense. I also saw in the Sork material 60 00:02:53.960 --> 00:02:56.719 a mention of binch. How does that fit in with 61 00:02:56.840 --> 00:02:59.840 Bash and Dash and ziz ah binch. 62 00:03:00.159 --> 00:03:02.960 Yeah, that's interesting because it touches on history and compatibility. 63 00:03:04.159 --> 00:03:08.639 Historically on Unix systems, binch was the standard path for 64 00:03:08.719 --> 00:03:09.520 the system shell. 65 00:03:09.719 --> 00:03:11.120 The original one kind of. 66 00:03:11.319 --> 00:03:14.199 Sort of yeah, but on modern Linux systems it's usually 67 00:03:14.240 --> 00:03:17.199 just a symbolic link. It often points to BASH or 68 00:03:17.240 --> 00:03:20.599 sometimes Dash, depending on the distribution's choice. You can actually 69 00:03:20.680 --> 00:03:22.960 check it yourself with the read link command. Just type 70 00:03:23.080 --> 00:03:23.840 read link binch. 71 00:03:24.000 --> 00:03:24.280 Oh me. 72 00:03:24.599 --> 00:03:26.599 Yeah, it's a subtle thing, but it shows how Linux 73 00:03:26.639 --> 00:03:29.520 evolve while making sure older scripts that expect binch to 74 00:03:29.520 --> 00:03:30.599 be there still were fun. 75 00:03:30.800 --> 00:03:34.280 Okay, that idea of different conversational styles, it's really clicking. 76 00:03:34.439 --> 00:03:36.319 But even if you pick the right style, sometimes you 77 00:03:36.360 --> 00:03:38.960 just need help figuring out what to say right. There 78 00:03:38.960 --> 00:03:41.319 are so many commands, so many options. 79 00:03:41.479 --> 00:03:44.560 Oh absolutely, and for that, the venerable MAN pages are 80 00:03:44.599 --> 00:03:45.840 your absolute best friends. 81 00:03:45.960 --> 00:03:48.680 Seriously, Man for manual, Yeah exactly. 82 00:03:48.919 --> 00:03:51.520 The man command is your primary help desk, and it's 83 00:03:51.520 --> 00:03:54.759 incredibly comprehensive. You can look up the manual page for 84 00:03:54.759 --> 00:03:58.599 a command like password, for instance, man password. But here's 85 00:03:58.639 --> 00:04:01.919 a key thing about Linux design. The same name can 86 00:04:01.960 --> 00:04:03.120 mean different things. 87 00:04:03.080 --> 00:04:05.520 Like the password command versus the password. 88 00:04:05.039 --> 00:04:08.400 File precisely, so, password could be the command to change 89 00:04:08.400 --> 00:04:11.280 your password, or it could refer to the it's set 90 00:04:11.280 --> 00:04:15.000 of password file where user info is stored. So to 91 00:04:15.039 --> 00:04:17.839 see the documentation specifically for the file. You'd specify the 92 00:04:17.839 --> 00:04:21.360 section number you type, Man five password section five. Yeah, 93 00:04:21.360 --> 00:04:23.360 the five foot tells Man to look in section five 94 00:04:23.360 --> 00:04:26.319 of the manual, which covers file formats and conventions. It 95 00:04:26.319 --> 00:04:30.480 turns that potential confusion into really precise information seeking. 96 00:04:30.720 --> 00:04:32.959 That's brilliant. So it's not just a command list, it's 97 00:04:32.959 --> 00:04:36.480 like a whole system library organized. What if Man says 98 00:04:36.600 --> 00:04:38.240 nothing appropriate found, does that happen? 99 00:04:38.360 --> 00:04:41.160 It does? Sometimes. Usually it's one of two things. First, 100 00:04:41.360 --> 00:04:44.199 maybe just a typo. The command line is super picky 101 00:04:44.240 --> 00:04:44.759 about spelling. 102 00:04:44.800 --> 00:04:46.920 Guilty is charged there sometimes we all are. 103 00:04:47.600 --> 00:04:50.600 Second, it could be that the man utilities database its 104 00:04:50.639 --> 00:04:54.720 index needs updating. On older systems, you might run make whatdies. 105 00:04:55.279 --> 00:04:58.360 On more modern ones, it's typically manned Y usually need 106 00:04:58.439 --> 00:05:03.079 super user privileges like pseudomand y to rebuild that index, like. 107 00:05:03.120 --> 00:05:05.160 Rebuilding the library's card catalog. 108 00:05:05.399 --> 00:05:06.319 Got it okay? 109 00:05:06.360 --> 00:05:09.160 And what about those moments We've all had them where 110 00:05:09.199 --> 00:05:12.079 you just ran a command maybe five minutes ago, maybe yesterday, 111 00:05:12.439 --> 00:05:15.720 and it was long and complicated and you really really 112 00:05:15.800 --> 00:05:17.079 don't want to type it all out again. 113 00:05:17.120 --> 00:05:20.959 Oh yeah, that's where your command line history is just invaluable. 114 00:05:21.319 --> 00:05:24.319 The shell remembers what you've typed. It's a huge timesaver. 115 00:05:24.480 --> 00:05:25.399 How do you access it? 116 00:05:25.560 --> 00:05:27.920 Just type history you'll get a numbered list of your 117 00:05:28.000 --> 00:05:28.800 racing command. 118 00:05:28.639 --> 00:05:30.759 Okay, a list, but rerunning them. 119 00:05:30.920 --> 00:05:34.240 Ah, here's the pro tip that seriously speeds things up. Yeah, 120 00:05:34.360 --> 00:05:36.839 you can re execute any command from that list just 121 00:05:36.920 --> 00:05:39.120 by typing do followed by its history number. 122 00:05:39.240 --> 00:05:42.480 Seriously, like point nine two zero or something exactly. 123 00:05:42.759 --> 00:05:45.839 Type point nine two zero, hit enter. The shell shows 124 00:05:45.839 --> 00:05:47.639 you the command it found at number nine twenty, and 125 00:05:47.639 --> 00:05:52.120 then runs it immediately. Yeah. It's fantastic for repeating complex 126 00:05:52.120 --> 00:05:54.639 commands or even just fixing a small typo in the 127 00:05:54.639 --> 00:05:57.839 previous one without retyping everything. A genuine timesaver. 128 00:05:58.199 --> 00:06:00.399 Okay, this is where the command line starts to feel 129 00:06:00.480 --> 00:06:02.639 less like just typing orders and more like I don't 130 00:06:02.639 --> 00:06:06.199 know a specialized language. Once you get past the basic commands, 131 00:06:06.279 --> 00:06:09.279 I often wonder what that next layer is. It feels 132 00:06:09.279 --> 00:06:11.519 like the shell must have its own grammar, its own 133 00:06:12.519 --> 00:06:14.879 secret code beyond simple words. 134 00:06:15.040 --> 00:06:17.040 You're absolutely right that secret code is made up of 135 00:06:17.079 --> 00:06:17.839 meta characters. 136 00:06:17.879 --> 00:06:19.240 Meta characters, Yeah, these are. 137 00:06:19.240 --> 00:06:22.079 Characters that have special meanings, special functions within the bash 138 00:06:22.120 --> 00:06:25.439 shell itself. They are incredibly powerful because they let you 139 00:06:25.480 --> 00:06:30.000 do things like match patterns, perform complex operations, manipulate whole 140 00:06:30.000 --> 00:06:32.399 groups of files with just a few keystrokes, like the 141 00:06:32.439 --> 00:06:35.800 asterisk the star exactly, the ass risk is a wildcard 142 00:06:35.920 --> 00:06:38.680 it matches any number of characters, or the question mark 143 00:06:38.759 --> 00:06:41.920 that matches just a single character. We also have bracketed 144 00:06:41.920 --> 00:06:43.279 wild cards like. 145 00:06:43.600 --> 00:06:48.319 Bayo okay, bayo that would match bet bit or bot precisely. 146 00:06:48.680 --> 00:06:51.959 And a really clever one is the carry symbol inside brackets. 147 00:06:52.319 --> 00:06:57.680 It negates the selection negats, so BeO would match bat 148 00:06:57.800 --> 00:07:01.439 or butt, but not bet bit or bought. It matches 149 00:07:01.519 --> 00:07:04.560 anything except what's in the brackets after the character. 150 00:07:04.600 --> 00:07:08.439 Oh okay. That's subtle but powerful. It turns a simple 151 00:07:08.439 --> 00:07:12.000 command like ULLs into this pattern matching engine for your files. 152 00:07:12.279 --> 00:07:16.240 You're not just listing your searching, filtering, tidying up logs, 153 00:07:16.560 --> 00:07:19.800 finding specific and fig files quickly. But what happens if 154 00:07:19.839 --> 00:07:22.279 you actually want to use one of those special characters 155 00:07:22.319 --> 00:07:24.959 like an asterisk or a question mark literally like in 156 00:07:24.959 --> 00:07:26.240 a file name or a message. 157 00:07:26.240 --> 00:07:29.279 Ah. Yes, that's where shell quoting comes in. And it's 158 00:07:29.319 --> 00:07:31.879 not just cosmetic, it's the fundamental control mechanism. 159 00:07:31.920 --> 00:07:32.720 Cotrol mechanism. 160 00:07:32.839 --> 00:07:36.000 Yeah, because without the right quoting, the shell might interpret 161 00:07:36.040 --> 00:07:38.920 those special characters in ways you didn't intend. It could 162 00:07:38.959 --> 00:07:40.680 mess up your command or worse. 163 00:07:41.040 --> 00:07:42.600 Okay, so how do we quote? 164 00:07:42.879 --> 00:07:45.800 Your two best friends are single quotes and double quotes? 165 00:07:45.839 --> 00:07:47.480 Single quotes and double clothes. What's the difference. 166 00:07:47.759 --> 00:07:52.560 It's crucial. Single quotes preserve the literal value of every 167 00:07:52.600 --> 00:07:56.240 single character inside them, no exceptions. If you type echo 168 00:07:56.360 --> 00:07:59.600 what's the deal, you will get exactly what's the deal. 169 00:07:59.720 --> 00:08:01.959 The asterisk is just an asterisk. 170 00:08:01.959 --> 00:08:05.759 Okay, literal lockdown with single quotes? What about double. 171 00:08:05.600 --> 00:08:08.920 Double quotes are slightly different. They preserve the literal value 172 00:08:08.959 --> 00:08:11.439 of most characters, but they still allow a few special 173 00:08:11.480 --> 00:08:15.079 things to happen inside like what like variable substitution using 174 00:08:15.120 --> 00:08:16.959 VASR and command substitution. 175 00:08:17.160 --> 00:08:20.920 Ah. So if I have a variable, say MYVR awesome, 176 00:08:21.079 --> 00:08:23.920 and I type echo this is MYVAR, it will. 177 00:08:23.759 --> 00:08:27.680 Actually output this is awesome. The shell substitutes the variables value. 178 00:08:27.720 --> 00:08:30.600 If you use single quotes, echo this is nyvar, you 179 00:08:30.720 --> 00:08:32.320 just get this is MYVR. 180 00:08:32.440 --> 00:08:37.360 Gotcha. Subtle but super important for writing commands correctly, especially scripts. Okay, 181 00:08:37.399 --> 00:08:40.600 that clarifies it perfectly. So once you're comfortable with the shell, 182 00:08:40.639 --> 00:08:44.240 it's language, the quoting. A massive part of Linux admin 183 00:08:44.320 --> 00:08:48.240 is dealing with text files right logs, configs, data. You 184 00:08:48.360 --> 00:08:50.519 must need a specific set of tools just for chewing 185 00:08:50.519 --> 00:08:51.639 through all that text quickly. 186 00:08:51.840 --> 00:08:55.159 Absolutely, it's a core skill, and thankfully Linux gives us 187 00:08:55.200 --> 00:08:58.159 this incredibly rich tool belt just for that. For just 188 00:08:58.240 --> 00:09:02.080 viewing files, the classic is CAT cat file name. It 189 00:09:02.200 --> 00:09:03.919 just dumps the whole file to your screen. 190 00:09:04.080 --> 00:09:08.200 Simple effective for a quick look. Yep, straightforward, and didn't 191 00:09:08.240 --> 00:09:11.360 the source mention BAT Like CAT with wings it did, 192 00:09:11.840 --> 00:09:12.240 BAT is. 193 00:09:12.200 --> 00:09:15.559 A more modern clone. It adds nice things like syntax highlighting, 194 00:09:15.759 --> 00:09:20.200 get integration makes looking at code, couldfig files much prettier, 195 00:09:20.480 --> 00:09:21.559 much easier to read. 196 00:09:21.840 --> 00:09:25.039 Nice. But what if you suspect weird and visible characters 197 00:09:25.080 --> 00:09:25.960 are messing things up? 198 00:09:26.200 --> 00:09:30.000 Good point for that. CAT has options like magia or 199 00:09:30.039 --> 00:09:33.759 adjuge that can help reveal non printing characters. And for 200 00:09:33.799 --> 00:09:36.399 an even deeper dive, there's the ODD command stands for 201 00:09:36.440 --> 00:09:37.120 octal dump. 202 00:09:37.200 --> 00:09:37.960 Octal dump. 203 00:09:38.080 --> 00:09:41.159 Yeah, it displays the files content in AKL or other formats. 204 00:09:41.399 --> 00:09:44.919 It's invaluable for finding those really sneaky non printing characters 205 00:09:44.919 --> 00:09:47.159 that might be causing weird issues. That a normal text 206 00:09:47.279 --> 00:09:48.279 editor just won't show you. 207 00:09:48.360 --> 00:09:51.639 Okay, useful for troubleshooting. What about huge files though, like 208 00:09:51.799 --> 00:09:55.080 massive log files, CAT would just fly by exactly. 209 00:09:55.279 --> 00:09:58.159 For big files you need pages. The old standby is 210 00:09:58.200 --> 00:09:58.840 more more. 211 00:09:59.279 --> 00:10:01.679 Let's you go four ford page by page with spacebar 212 00:10:01.799 --> 00:10:02.440 right right. 213 00:10:02.360 --> 00:10:04.960 Page by page with space, line by line with enter. 214 00:10:05.360 --> 00:10:08.360 But the catch with more is you can't easily go backward. 215 00:10:08.480 --> 00:10:10.360 Ah, so what's better less? 216 00:10:10.960 --> 00:10:13.519 The command is less. It's the more powerful pager. In fact, 217 00:10:13.720 --> 00:10:16.720 man pages use less by default behind the scenes. 218 00:10:16.440 --> 00:10:17.360 Unless it is more. 219 00:10:17.559 --> 00:10:21.159 Huh exactly Less lets you move forward and backward using 220 00:10:21.279 --> 00:10:24.360 arrow keys page up, down, and crucially, it has powerful 221 00:10:24.440 --> 00:10:27.960 search features built in to search forward, to search backward. 222 00:10:28.519 --> 00:10:30.720 Much more versatile for digging through dense text. 223 00:10:31.000 --> 00:10:34.240 Makes sense, so we can view files navigate big ones. 224 00:10:34.600 --> 00:10:36.440 How do we start pulling out just the bits we 225 00:10:36.480 --> 00:10:37.879 need or getting quick summaries. 226 00:10:38.120 --> 00:10:40.799 Right for summaries or just peaking at the ends, we 227 00:10:40.919 --> 00:10:41.919 have head and tail. 228 00:10:42.159 --> 00:10:43.840 Head for the beginning, tail for the end. 229 00:10:43.960 --> 00:10:47.559 Precisely. Head file name shows the first ten lines by default, 230 00:10:47.559 --> 00:10:50.200 Tail file name shows the last ten. You can change 231 00:10:50.200 --> 00:10:52.440 the number of lines with modd end and tail has 232 00:10:52.440 --> 00:10:53.679 that killer feature tail. 233 00:10:53.519 --> 00:10:57.399 Space follow mode for watching logs in real time. 234 00:10:57.559 --> 00:11:02.039 Exactly tail dash F varlogslog or whatever. You see new 235 00:11:02.120 --> 00:11:05.000 lines appear as they're written to the file. Absolute life 236 00:11:05.000 --> 00:11:08.279 saver when troubleshooting live issues. You just watch that log 237 00:11:09.039 --> 00:11:09.879 waiting for the air. 238 00:11:10.120 --> 00:11:12.240 Been there? What about summaries like counts. 239 00:11:11.960 --> 00:11:16.600 For counts, there's WC word count WC WC file name 240 00:11:16.840 --> 00:11:18.840 gives you the number of lines, words and bytes in 241 00:11:18.879 --> 00:11:22.240 the file. Super quick overview. And for pulling out specific 242 00:11:22.279 --> 00:11:26.840 pieces of data from lines, especially structured data, cut is fantastic. 243 00:11:27.080 --> 00:11:27.799 How does that work? 244 00:11:27.919 --> 00:11:30.440 You tell it how the data is separated, like using 245 00:11:30.440 --> 00:11:33.039 a comma or a tabs, a delimiter, and then which 246 00:11:33.080 --> 00:11:36.559 field number you want ted crucial for parsing things like 247 00:11:36.639 --> 00:11:39.120 CSV files or specific log formats. 248 00:11:39.159 --> 00:11:43.480 Okay, headtail, WC cut pretty fundamental tools for slicing and 249 00:11:43.559 --> 00:11:47.960 dicing text. What about finding specific patterns or sorting the 250 00:11:48.039 --> 00:11:50.080 data that feels like something you'd need constantly? 251 00:11:50.200 --> 00:11:53.200 Oh? Absolutely essential? And for searching the undisputed king. 252 00:11:53.120 --> 00:11:57.759 Is grip grip global regular expression print right, that's the one. 253 00:11:57.840 --> 00:12:02.360 It searches files for lines containing a pattern. Basic usagep 254 00:12:02.600 --> 00:12:07.399 pattern file name like rep root et cetera. Pass finds 255 00:12:07.480 --> 00:12:10.879 all lines with root in the password file. I remember 256 00:12:10.879 --> 00:12:14.399 debugging the script once logs were going crazy. Rep was 257 00:12:14.399 --> 00:12:16.600 the only way it could possibly sift through thousands of 258 00:12:16.679 --> 00:12:20.399 lines to find the error messages I needed. It's incredibly versatile. 259 00:12:20.559 --> 00:12:23.559 Can it do more than just find lines with a pattern? 260 00:12:23.759 --> 00:12:26.960 Definitely? Use gp dash v to invert the match show 261 00:12:26.960 --> 00:12:29.200 lines that do not contain the pattern. And you can 262 00:12:29.279 --> 00:12:32.320 use regular expressions for much more precise matching, like matches 263 00:12:32.360 --> 00:12:34.679 the start of a line matches the end ah. 264 00:12:34.720 --> 00:12:37.240 So you could do something like grap dash v knowledge 265 00:12:37.240 --> 00:12:38.240 and except for a pass. 266 00:12:38.080 --> 00:12:41.840 Rate exactly, that would find user accounts whose lines don't 267 00:12:41.960 --> 00:12:44.759 end with knowledge, in effectively accounts that can log in. 268 00:12:45.360 --> 00:12:47.519 Super powerful for filtering and sorting. 269 00:12:47.600 --> 00:12:49.080 If I g repped a bunch of lines, could I 270 00:12:49.120 --> 00:12:49.519 sort them? 271 00:12:49.559 --> 00:12:52.840 Yep? Using the sort command. By default, it sorts alphabetically. 272 00:12:52.919 --> 00:12:53.879 What if they're numbers? 273 00:12:54.159 --> 00:12:57.200 Use sort nash an for a numerical sort like sort 274 00:12:57.320 --> 00:13:00.879 nash incounts dot txt and a hand trick with sort 275 00:13:00.919 --> 00:13:04.480 is the ASHO option. Sort natcho output file dot txt, 276 00:13:05.159 --> 00:13:08.720 input file dot txt. It sorts input file dot txt 277 00:13:09.080 --> 00:13:12.120 and writes the result directly to output file dot txt 278 00:13:12.639 --> 00:13:13.120 very clean. 279 00:13:13.320 --> 00:13:16.600 Okay. These tools are clearly the building blocks for manipulating text. 280 00:13:16.679 --> 00:13:19.559 But this next part, this feels like where the command 281 00:13:19.639 --> 00:13:22.320 line transforms from just a toolbox into a whole workshop. 282 00:13:22.639 --> 00:13:24.720 It's not just about what each command does, but how 283 00:13:24.759 --> 00:13:27.240 they talk to each other, right, how they connect, That 284 00:13:27.320 --> 00:13:29.600 seems key to making them more powerful together. 285 00:13:29.879 --> 00:13:32.159 That is exactly where the true power lies. It happens 286 00:13:32.200 --> 00:13:35.600 through streams, pipes, and redirection. See, every command usually works 287 00:13:35.639 --> 00:13:36.120 with three. 288 00:13:35.919 --> 00:13:37.879 Standard stream streams like streams of data. 289 00:13:37.919 --> 00:13:41.360 Precisely, there's stda N standard input that's where a command 290 00:13:41.360 --> 00:13:43.519 gets its input. Usually that's your ty board. Then sdd 291 00:13:43.639 --> 00:13:46.679 OAE standard output where the command sends its normal results, 292 00:13:46.879 --> 00:13:50.279 usually your screen, and sdd AIR standard air where air 293 00:13:50.279 --> 00:13:52.519 messages go, also usually to your screen by. 294 00:13:52.360 --> 00:13:56.360 Default s TVs TDDA s td air. Okay. So this 295 00:13:56.519 --> 00:13:59.200 idea of redirection, it means we can change where those 296 00:13:59.200 --> 00:14:01.919 streams go instead of the keyboorder screen exactly. 297 00:14:02.240 --> 00:14:04.799 You can reroute them. The symbol redirects std o. 298 00:14:04.840 --> 00:14:07.399 UT sends output to a file, yes. 299 00:14:07.480 --> 00:14:09.960 But be careful overwrites a file if it exists. 300 00:14:10.080 --> 00:14:13.360 Boof gone ouch Okay, caution needed. What if I want 301 00:14:13.360 --> 00:14:14.480 to add to a file. 302 00:14:14.559 --> 00:14:18.279 Use perster the double greater than a pens stda ut 303 00:14:18.440 --> 00:14:20.320 to the end of the file. Much safer. If you 304 00:14:20.360 --> 00:14:21.720 want to keep existing. 305 00:14:21.279 --> 00:14:25.480 Content overwrites a pens Got it? What about st er 306 00:14:25.720 --> 00:14:27.080 the error messages. 307 00:14:26.679 --> 00:14:29.960 You redirect STDOJ using too the two refers to file 308 00:14:30.000 --> 00:14:32.799 descriptor two, which is st e R. So something like 309 00:14:32.840 --> 00:14:35.919 fine dash name dot log two finders dot txt would 310 00:14:36.000 --> 00:14:38.960 run the find command, but any permission denied errors would 311 00:14:38.960 --> 00:14:41.519 go into finders dot txt. Not clutter your screen. 312 00:14:41.840 --> 00:14:45.279 Ah, separating the good output from the bad useful? Can 313 00:14:45.320 --> 00:14:46.720 you send both to the same place? 314 00:14:46.879 --> 00:14:49.639 Yes, you can use an snore or the slightly older 315 00:14:49.679 --> 00:14:52.840 two and one. Both redirect stdo and SDDO to the 316 00:14:52.840 --> 00:14:56.360 same file. Great for capturing absolutely everything at command outputs 317 00:14:56.480 --> 00:14:58.919 errors included for logging or later analysis. 318 00:14:58.960 --> 00:15:01.720 Okay, redirection, let's us manage output. But the ultimate connector 319 00:15:01.960 --> 00:15:04.240 the pipe. This is where the magic of chaining commands 320 00:15:04.240 --> 00:15:05.159 really happens, isn't it. 321 00:15:05.159 --> 00:15:07.639 It truly is the pipe character that vertical bar. It's 322 00:15:07.679 --> 00:15:08.600 a complete game changer. 323 00:15:08.679 --> 00:15:10.080 It's what does it do technically? 324 00:15:10.399 --> 00:15:13.320 It takes the sdbout of the command before the pipe 325 00:15:13.600 --> 00:15:16.279 and feeds it directly as the SDDI in to the 326 00:15:16.320 --> 00:15:17.440 command after the pipe. 327 00:15:17.559 --> 00:15:20.320 Whoa, so output becomes input Exactly. 328 00:15:20.360 --> 00:15:22.759 It's like building an assembly line for your data right 329 00:15:22.759 --> 00:15:26.279 there on the command line. You filter, process, count, transform 330 00:15:26.320 --> 00:15:29.840 step by step like our earlier example. Yep rep binbash 331 00:15:29.879 --> 00:15:35.279 et cetera, rep binbash, et cetera PASTWCDL. 332 00:15:34.080 --> 00:15:38.039 Right grep finds the lines stdout. The pipe sends those 333 00:15:38.080 --> 00:15:42.639 lines to wc as stdin, and WCDL counts them. Brilliant. 334 00:15:42.679 --> 00:15:45.600 It lets you combine simple tools to do complex tasks 335 00:15:45.679 --> 00:15:47.759 without creating temporary files all the time. 336 00:15:47.879 --> 00:15:51.279 I love that building complex operations from simple parts. Now, 337 00:15:51.320 --> 00:15:53.200 what if you want to see the output and save 338 00:15:53.200 --> 00:15:55.399 it to a file simultaneously? Do you have to run 339 00:15:55.440 --> 00:15:56.200 it twice? Nope. 340 00:15:56.279 --> 00:15:57.360 That's where the T command comes in. 341 00:15:57.440 --> 00:15:59.519 With the T like a T junction in plumbing. 342 00:15:59.600 --> 00:16:02.720 Exactly like that, it reads from stdi in and writes 343 00:16:02.759 --> 00:16:06.080 both to std out your screen and to a file 344 00:16:06.120 --> 00:16:09.720 you specify. So greb binbasha, et cetera, pass roodett Bash 345 00:16:09.840 --> 00:16:12.440 users dot txt. You'll see the list of Bash users 346 00:16:12.440 --> 00:16:14.519 on the screen, and they'll be saved in Bash users 347 00:16:14.519 --> 00:16:15.399 dot txt that. 348 00:16:15.399 --> 00:16:18.519 Is incredibly handy auditing, reporting, just keeping a record. 349 00:16:19.159 --> 00:16:21.879 And another powerful tool that works beautifully with pipes is 350 00:16:22.200 --> 00:16:24.120 Here's on the stream editor. 351 00:16:24.159 --> 00:16:27.080 Stream editor it edits data as it flows. 352 00:16:26.799 --> 00:16:30.440 Through precisely, it performs text transformations on the fly. The 353 00:16:30.480 --> 00:16:35.039 classic example is substitution echo I like cake, said scape donuts. 354 00:16:35.360 --> 00:16:39.639 The said command gets I like cake as input, replaces 355 00:16:39.679 --> 00:16:42.960 cake with donuts, and outputs I like donuts. 356 00:16:42.639 --> 00:16:44.840 Find and replaced. But in a live stream. 357 00:16:45.240 --> 00:16:45.559 Wow. 358 00:16:45.720 --> 00:16:48.639 Okay. Speaking of powerful tools that work with input, I 359 00:16:48.639 --> 00:16:50.960 think I heard the source mentioned one that sounds a 360 00:16:51.000 --> 00:16:53.919 bit like a pirate. Does zargs ring a bell? Ah? 361 00:16:54.000 --> 00:16:56.960 Yes, the mighty zarks. It definitely sounds a bit pyraty. 362 00:16:57.039 --> 00:16:59.879 How does it do? It sounds important for building commands. 363 00:16:59.559 --> 00:17:02.720 It's fantas pastic For dynamic command building. Zargs reads items 364 00:17:02.720 --> 00:17:05.279 from standard input, usually lines of text, and builds and 365 00:17:05.359 --> 00:17:08.319 executes command lines using those items as arguments. 366 00:17:08.440 --> 00:17:11.839 So if one command outputs a list of files. 367 00:17:11.559 --> 00:17:14.279 Dotrics can take that list and feed each file name 368 00:17:14.359 --> 00:17:17.480 as an argument to another command like RM or CP 369 00:17:17.880 --> 00:17:21.720 or anything else. For example, LS one emptyfile, dot txt, 370 00:17:22.119 --> 00:17:26.680 zargs dot pusrbin, RM, dotch. One's dotch one lists the 371 00:17:26.720 --> 00:17:30.240 matching files one per line. Zargs takes each line file 372 00:17:30.359 --> 00:17:32.960 name and runs us arban nerum with that filename as 373 00:17:32.960 --> 00:17:35.759 an argument. The dot p makes it prompt you first, 374 00:17:35.960 --> 00:17:37.880 which is safer with RM. 375 00:17:37.440 --> 00:17:40.480 So it turns a list into action arguments. That's incredibly 376 00:17:40.519 --> 00:17:42.519 powerful for batch operations, it really is. 377 00:17:42.599 --> 00:17:44.920 It lets you connect commands in ways that simple piping 378 00:17:44.960 --> 00:17:47.440 sometimes can't handle, especially when you need to use the 379 00:17:47.480 --> 00:17:50.160 input as command line arguments rather than just standard input. 380 00:17:50.599 --> 00:17:53.359 Now why should you care about all this redirection piping, 381 00:17:53.440 --> 00:17:56.599 t said zarg stuff. Because these techniques let you grab 382 00:17:56.640 --> 00:18:00.599 information instantly, process huge log files, sufficiently filtered dat exactly 383 00:18:00.640 --> 00:18:02.880 how you need it for reports, and automate task as 384 00:18:02.920 --> 00:18:05.720 it would be incredibly tedious or even impossible to do manually. 385 00:18:06.039 --> 00:18:08.960 You're essentially building these tiny specialized programs right there on 386 00:18:09.000 --> 00:18:12.759 the command line. You're customizing your workflow to an unbelievable degree. 387 00:18:12.920 --> 00:18:15.400 It really unlocks the full power of Linux for efficiency 388 00:18:15.400 --> 00:18:15.960 and precision. 389 00:18:16.119 --> 00:18:19.240 Wow. We've really only just scratched the surface of the 390 00:18:19.279 --> 00:18:22.119 Linux command line here, haven't we, But what a powerful 391 00:18:22.160 --> 00:18:25.839 surface it is. We've seen how understanding the shell is key, 392 00:18:25.960 --> 00:18:29.440 like knowing who you're talking to, then mastering those metacharacters 393 00:18:29.440 --> 00:18:33.000 and quoting, speaking the Shells language correctly, and then leveraging 394 00:18:33.079 --> 00:18:37.640 that incredible power of streams, pipes, redirection, rep sort sargs, 395 00:18:38.319 --> 00:18:43.000 turning these complex tasks into simple, almost elegant solutions. 396 00:18:43.200 --> 00:18:47.039 That's exactly it. It's not just about memorizing commands in isolation. 397 00:18:47.160 --> 00:18:50.680 It's about understanding how they fit together, how you chain them, 398 00:18:50.920 --> 00:18:54.359 how you harness their individual strengths to achieve much bigger things. 399 00:18:54.640 --> 00:18:57.759 It's about building a workflow that's efficient for you, that's 400 00:18:57.799 --> 00:18:59.920 precise and incredibly flexible. 401 00:19:00.119 --> 00:19:02.160