Would you like to inspect the original subtitles? These are the user uploaded subtitles that are being translated: 1 00:00:00,170 --> 00:00:06,770 Hello everybody and welcome to part two of this tutorial. Let's go ahead and save the 2 00:00:06,770 --> 00:00:14,059 file. Press control-O to output the file. It says file filename to write. You can actually 3 00:00:14,059 --> 00:00:19,390 modify it here. You can type in some letters or whatever you want to change the name here. 4 00:00:19,390 --> 00:00:24,820 You can even change the extension if you want. There is no need for the time being. I'm just 5 00:00:24,820 --> 00:00:30,240 going to go ahead and save it as "test." Just press enter. There you go. It says, "wrote 6 00:00:30,240 --> 00:00:37,620 one line. Hit control-X to exit. There we go. Clear the screen. Now, I'm going to use 7 00:00:37,620 --> 00:00:42,399 cat command to get a listing of this particular file, which is far more reasonable than the 8 00:00:42,399 --> 00:00:46,809 previous one, which you couldn't read. The command, by the way, was functioning properly 9 00:00:46,809 --> 00:00:53,119 but it was mostly a binary file. Therefore I mean, it gave you listing but you couldn't 10 00:00:53,119 --> 00:00:59,969 really read anything from it. So just go ahead and type in cat test and there we go. It says, 11 00:00:59,969 --> 00:01:08,770 "some random text goes here." That is the text that we have typed into the test file 12 00:01:08,770 --> 00:01:13,939 and you can cat it like this. These things are very good, especially with files that 13 00:01:13,939 --> 00:01:21,200 you want to make sure not to change them in any way, you don't want to make any accidental 14 00:01:21,200 --> 00:01:26,799 changes or anything of the kind and you want to quickly see what is located within that 15 00:01:26,799 --> 00:01:33,840 file. There is another way of doing this. Basically, it's "ls." Let's go ahead and get 16 00:01:33,840 --> 00:01:44,270 over to "cd etc/apt/." "Ls." We have plenty of files to work with. Let's take sources.list 17 00:01:44,270 --> 00:01:51,880 as an example here. So if I do "cat sources.list" I'm going to get everything that is within 18 00:01:51,880 --> 00:01:58,679 that file as before. It is listed in my terminal, it's here to stay. It's not going anywhere. 19 00:01:58,679 --> 00:02:02,499 There is another command which I could use. Just go ahead and clear the screen. It is 20 00:02:02,499 --> 00:02:10,670 called "less." If I type, "less sources.list" I will be prompted with a new tab where I 21 00:02:10,670 --> 00:02:16,170 can actually view things here. Not a new terminal tab, but a new workspace within the within 22 00:02:16,170 --> 00:02:22,430 the terminal itself. When I press Q I exit and nothing will be displayed here. So very 23 00:02:22,430 --> 00:02:30,760 nice in terms of being neat, organized and so on and so forth. So less and cat are very 24 00:02:30,760 --> 00:02:37,959 nice things. You can use, for example, "cat sources.list" and the command that I have 25 00:02:37,959 --> 00:02:45,599 previously mentioned is "grep." "Grep" means you pull something, grep something from somewhere 26 00:02:45,599 --> 00:02:51,569 else. Here's what I mean by it. Type in "cat sources.list" and you type in a pipe. This 27 00:02:51,569 --> 00:02:57,319 symbol here. It's called a pipe which basically states whatever the output of this is pipe 28 00:02:57,319 --> 00:03:03,950 it to whatever command comes here. So, I'm just going to type in "grep" and let's say 29 00:03:03,950 --> 00:03:13,610 I want to type in, "src." Press enter. Excellent. So it will only print lines that have "src" 30 00:03:13,610 --> 00:03:21,439 in them. Linux is case-sensitive. When you are grepping, it's going to check whether 31 00:03:21,439 --> 00:03:35,379 it's lowercase or not. You can give it an ignore case. You can type this, "-i" to ignore 32 00:03:35,379 --> 00:03:39,049 the case. This time, you're going to get the same output because there are no different 33 00:03:39,049 --> 00:03:45,269 things within this file. You get the general idea. So this is how you would use "cat" with 34 00:03:45,269 --> 00:03:53,590 grep to pull things out of a file. Very important. This is a huge part of the Linux terminal-- 35 00:03:53,590 --> 00:03:59,480 filtering through text files. Primarily because we are going to be doing large network scans 36 00:03:59,480 --> 00:04:05,959 and we will want to create files from which we will be able to pool useful information. 37 00:04:05,959 --> 00:04:12,599 We will later in turn pass this information to other tools to do something with. Anyway, 38 00:04:12,599 --> 00:04:23,590 just go ahead and clear to screen for the time being. You also have "echo." Type "echo 39 00:04:23,590 --> 00:04:35,200 "I AM ALIVE"." It will echo these words it literally is an echo. You type something into 40 00:04:35,200 --> 00:04:41,030 it and it echoes them here. Let's go back to the home directory, get a listing and use 41 00:04:41,030 --> 00:04:46,240 exactly the same command echo live. By the way, you can scroll through previous commands 42 00:04:46,240 --> 00:04:52,230 by using arrow key. So using the up arrow key or the down arrow key, you can scroll 43 00:04:52,230 --> 00:04:58,580 back through previous commands and you don't need to retype them. So I am alive. I'm going 44 00:04:58,580 --> 00:05:11,610 to insert this. I will use a ">" and type in "test." This will echo "I AM ALIVE" into 45 00:05:11,610 --> 00:05:19,590 test. It has replaced the contents of the test, which was "some random text goes here" 46 00:05:19,590 --> 00:05:28,030 into, "I AM ALIVE." Very nice command to have. You can change variable names, variable values 47 00:05:28,030 --> 00:05:32,540 with echo and so on and so forth. We will use this a bit more as we progress through 48 00:05:32,540 --> 00:05:38,420 the course. I don't really want to get in-depth here. Primarily because later on when we have 49 00:05:38,420 --> 00:05:45,610 clear examples that directly relate to what we are doing, which is basically testing, 50 00:05:45,610 --> 00:05:51,870 then you will see more advanced usage of pretty much all of these commands-- especially grep. 51 00:05:51,870 --> 00:05:59,970 You have "touch."Touch" is a quick way to create files. So, for example, I can type, 52 00:05:59,970 --> 00:06:11,530 "touch file1 file2 file3." Press enter, "ls." You see, it immediately created three files. 53 00:06:11,530 --> 00:06:24,110 That is a very quick method to create any amount of files. You can specify a folder. 54 00:06:24,110 --> 00:06:29,900 You can create this file in home, this one in var, this one in varlog, and so on and 55 00:06:29,900 --> 00:06:39,190 so forth. Down below, you have "mkdir." Type in, "mkdir" and it makes a directory. So you 56 00:06:39,190 --> 00:06:45,880 are making some sort of a directory. Let's say this the name of this directory will be 57 00:06:45,880 --> 00:06:54,280 "placeToBe." If I hit "ls." There we go. It states that is the does that this file is 58 00:06:54,280 --> 00:06:59,950 actually a directory, which is PlaceToBe. I can even navigate to it and say, "PlaceToBe 59 00:06:59,950 --> 00:07:07,740 ls." There is nothing in it but you get the idea. You can make directories in such a fashion. 60 00:07:07,740 --> 00:07:13,580 Now, if I type "chown" it allows you to change the ownership of a particular file. Since 61 00:07:13,580 --> 00:07:17,880 we only have a single user here, which is root, there isn't really any point in doing 62 00:07:17,880 --> 00:07:22,710 so. If we create some of the new users we could do that. However, we don't need them. 63 00:07:22,710 --> 00:07:28,300 I'll just show you how this would work. For example, if the owner of the file was not 64 00:07:28,300 --> 00:07:36,110 root and you want to change it to root, do the following. Type, "chown," then you would 65 00:07:36,110 --> 00:07:43,120 type the username ":" and the user group. The user group and the username are usually 66 00:07:43,120 --> 00:07:49,270 the same on your home PC, unless you have some bigger servers or something like that. 67 00:07:49,270 --> 00:07:56,370 Then just specify the name of the file. You can type "test." There it will effectively 68 00:07:56,370 --> 00:08:05,650 change the ownership of file test to the username root, who is from the user group root. If 69 00:08:05,650 --> 00:08:13,710 I do "ls la" it states who the owners are and which groups actually owned the files 70 00:08:13,710 --> 00:08:23,300 as well. Clear the screen. There is another more used command. It's called "chmod." This 71 00:08:23,300 --> 00:08:28,250 command allows you to change file permissions. This is something that you will need to use 72 00:08:28,250 --> 00:08:35,889 on daily basis and quite often. Primarily because, you see if I have an executive file 73 00:08:35,889 --> 00:08:55,750 in Linux, for example. Let's just go ahead and type in, "echo hello." I want to that 74 00:08:55,750 --> 00:09:10,069 to test and I want to test to test.sh. "Sh" is basically an executable one, that's a bash 75 00:09:10,069 --> 00:09:15,000 script for Linux that in such a way you can automate tasks. We will deal with it in greater 76 00:09:15,000 --> 00:09:19,370 depth as we proceed through the tutorial. You will need to be acquainted with bash scripting 77 00:09:19,370 --> 00:09:24,490 definitely. Bash scripting is very similar to the terminal itself, so pretty much all 78 00:09:24,490 --> 00:09:29,129 the commands used in the terminal, can be used by scripting as well. You basically just 79 00:09:29,129 --> 00:09:36,620 combine a bunch of them in a file. Now, I want this to be my executable, but you see 80 00:09:36,620 --> 00:09:42,850 the way to to start executables is "./" as stated previously that's the command to start 81 00:09:42,850 --> 00:09:48,459 any executable. If I type in test, and press that, it doesn't give me a list of possibilities. 82 00:09:48,459 --> 00:09:55,759 Now, surely test.sh is an executable, but no you see, it doesn't have a permission to 83 00:09:55,759 --> 00:10:02,920 be an executable file. See here the difference, take a look at this file and take a look at 84 00:10:02,920 --> 00:10:08,999 this file. This one is green, this one is not. Now look at their permissions. So you 85 00:10:08,999 --> 00:10:16,569 see, it has a markation that is executable for all groups, users, etc., while this one 86 00:10:16,569 --> 00:10:24,149 up here does not have such permissions. You need to change that. What you do to change 87 00:10:24,149 --> 00:10:32,839 it is, "chmod." You would type in, "+x." If you want the file to be writable you type, 88 00:10:32,839 --> 00:10:38,249 "+w," if you want it to be executable "+x," if you want to be able to read the file, "+r," 89 00:10:38,249 --> 00:10:45,910 very simple. There is also a way of doing this with numbers. You can type in, "755." 90 00:10:45,910 --> 00:10:51,560 Don't try remembering all those modes. Whatever you need go on the internet and check. It 91 00:10:51,560 --> 00:11:00,720 can be quite complicated, but these three you need to know: +x, +r, and +w. Also 777, 92 00:11:00,720 --> 00:11:06,639 which is a global mode. This is the mode which is not recommended for actual usage, but you 93 00:11:06,639 --> 00:11:12,839 use "chmode" to actually test or troubleshoot things. For example, if you want to be absolutely 94 00:11:12,839 --> 00:11:19,689 sure that certain actions are not being prevented due to file permissions, you change the mode 95 00:11:19,689 --> 00:11:25,089 of those files to 777, which is the global mode that anybody can do anything with the 96 00:11:25,089 --> 00:11:29,829 file. If you still have an error message you know that it is absolutely not related to 97 00:11:29,829 --> 00:11:35,879 anything in regards to permissions. So, those four things to do need to know. You can just 98 00:11:35,879 --> 00:11:50,149 go ahead and type, "chmod +x test.sh," press enter. If I do "ls la" once again, you will 99 00:11:50,149 --> 00:11:57,240 see that test.sh is now executable. Let me just run it and there you go. If I run this 100 00:11:57,240 --> 00:12:07,249 it's going to echo "hello" on my terminal screen. There's a bit more to go. Not much 101 00:12:07,249 --> 00:12:12,100 more left. There is just one more command that I would really like show you. This can 102 00:12:12,100 --> 00:12:17,769 be a very dangerous command. Indeed, it can mess you up in ways you can't begin to imagine 103 00:12:17,769 --> 00:12:27,959 yet. that is the command "rm." "Rm" is basically remove. Once you remove things with this command, 104 00:12:27,959 --> 00:12:36,040 it's next to impossible to recover pretty much anything. So, if I type in, "rm test.sh," 105 00:12:36,040 --> 00:12:41,540 it's going to remove it. It's no longer going to be there. If I go ahead and navigate over 106 00:12:41,540 --> 00:12:51,660 to PlaceToBe and I "touch test" to make a new file there. If I go ahead and say "RM 107 00:12:51,660 --> 00:12:57,050 PlaceToBe." It will say "rm cannot remove place to be because it is a directory." This 108 00:12:57,050 --> 00:13:03,389 is a failsafe of the rm. So, you wouldn't delete a full directory because you will be 109 00:13:03,389 --> 00:13:14,129 able to recover it, and that would be really bad. What you can do is type in, "rm -f PlaceToBe." 110 00:13:14,129 --> 00:13:20,730 Cannot remove directory. Okay, no problems. Sometimes you get stuck. I'm deliberately 111 00:13:20,730 --> 00:13:27,220 going to leave this part in the tutorial. I'll just troubleshoot it. So you type in, 112 00:13:27,220 --> 00:13:35,149 "--help." Here you have recursive remove directories and their contents recursively. So, that's 113 00:13:35,149 --> 00:13:40,019 a very nice option. So, let's just go ahead and do that because this will go into the 114 00:13:40,019 --> 00:13:45,279 folder and remove everything within the folder and the folder itself, hopefully. So, just 115 00:13:45,279 --> 00:13:52,019 go ahead and type in, "rm -r PlaceToBe," press enter. There you go. It has deleted it. There 116 00:13:52,019 --> 00:14:01,939 we go, it is no longer there. The "-f" that I have used is force. It will not ask you 117 00:14:01,939 --> 00:14:06,959 any questions. It will delete the folder or file, which can be also very dangerous. When 118 00:14:06,959 --> 00:14:15,649 you're using "rm," you always want to be asked questions. In any case, as I said, I deliberately 119 00:14:15,649 --> 00:14:21,220 left his to show you that even if you get stuck worry about it. I get stuck all the 120 00:14:21,220 --> 00:14:28,430 time. If you don't know what to type in, what argument to pass, just type in "--help." Take 121 00:14:28,430 --> 00:14:35,959 a look at what you can actually type, read a little bit and then use the options. Try 122 00:14:35,959 --> 00:14:41,019 it out, sometimes it will work, sometimes it won't. More often than not, you will be 123 00:14:41,019 --> 00:14:45,529 able to figure it out from the help menu. If you can't figure it out from help menu, 124 00:14:45,529 --> 00:14:51,079 just typed in "man rm" and you can read pretty much everything there is to know about this 125 00:14:51,079 --> 00:14:56,569 command here. If you really can't perform the task, if you can find anything useful 126 00:14:56,569 --> 00:15:03,680 here, forums are your next best bet. Trust me you will succeed in doing it. In any case, 127 00:15:03,680 --> 00:15:07,899 this was a brief introduction some of the basic commands that we will use. Please make 128 00:15:07,899 --> 00:15:13,689 sure that you know what each one of these commands does, at least basic functions. Later 129 00:15:13,689 --> 00:15:20,180 on we will get in-depth, do more advanced stuff and use more advanced commands by combining 130 00:15:20,180 --> 00:15:26,119 them, and so on. In any case, I bid you all farewell. I hope to see you in the next tutorial. 17299