1 00:00:00,000 --> 00:00:01,949 [No audio] 2 00:00:01,949 --> 00:00:06,329 Help Commands. Now what are the help commands that 3 00:00:06,329 --> 00:00:09,779 are used in a Linux environment that will give you 4 00:00:09,779 --> 00:00:14,129 some of the information or some help about other 5 00:00:14,129 --> 00:00:19,829 commands. There are three types of help command 6 00:00:20,039 --> 00:00:22,469 that are used in most of the Linux distributions. 7 00:00:23,009 --> 00:00:26,309 The first one is whatis. So whenever you run a 8 00:00:26,309 --> 00:00:29,789 command whatis followed by the command that you 9 00:00:29,789 --> 00:00:33,539 want to inquire about, you will run whatis and 10 00:00:33,539 --> 00:00:37,019 space then command. This will give you a quicker 11 00:00:37,019 --> 00:00:39,599 a shorter version of the information about the 12 00:00:39,599 --> 00:00:42,659 command that you're looking for. The next one we 13 00:00:42,659 --> 00:00:45,419 have is the command whichever command you want to 14 00:00:45,419 --> 00:00:49,499 run, let's say ls space and then --help. 15 00:00:49,619 --> 00:00:54,869 This will give you a little bigger, a longer 16 00:00:54,869 --> 00:00:58,109 version of the help, a bit more details about that, 17 00:00:58,109 --> 00:01:01,859 the options about that command, and the last one is 18 00:01:01,889 --> 00:01:05,998 man which is stands for manual, man space followed 19 00:01:05,998 --> 00:01:08,939 by the command, the command name itself. When you 20 00:01:08,939 --> 00:01:12,359 run that you will get a complete full listing of 21 00:01:12,359 --> 00:01:15,899 the command descriptions to help about it. So now 22 00:01:15,899 --> 00:01:18,929 let's look at our Linux machine and we'll see how 23 00:01:18,929 --> 00:01:24,899 these commands work. So we are here in our Linux 24 00:01:24,899 --> 00:01:27,959 machine. Let's do the clear, and we will find out 25 00:01:27,959 --> 00:01:31,499 who we are. Again whoami, we are ourself, we type 26 00:01:31,529 --> 00:01:34,229 clear. The first command that we learned, we're going to 27 00:01:34,259 --> 00:01:39,149 run is whatis, it's all one word, space, let's say 28 00:01:39,179 --> 00:01:43,889 ls. This will tell you that ls lists the 29 00:01:43,889 --> 00:01:47,249 directory contents. The next one we will run is 30 00:01:47,279 --> 00:01:51,209 whatis cd. That's what tells you the bash built-in 31 00:01:51,209 --> 00:01:54,119 command. The CD is a bash built in command meaning 32 00:01:54,119 --> 00:01:58,379 when you have a your Linux system installed, it 33 00:01:58,379 --> 00:02:01,679 comes in as people's command. And what it does, it 34 00:02:01,679 --> 00:02:05,069 changed the working directory from one directory 35 00:02:05,099 --> 00:02:07,739 of course to another. Well, let's try the same 36 00:02:07,739 --> 00:02:12,449 command to whatis pwd, tells you print name of 37 00:02:12,449 --> 00:02:15,149 current working directory, return working directory 38 00:02:15,149 --> 00:02:20,849 name. So why do we have two different answers for 39 00:02:20,849 --> 00:02:23,579 one command is because we have two different 40 00:02:23,579 --> 00:02:26,039 sources or two different dictionary already 41 00:02:26,039 --> 00:02:29,069 installed, or you could say two different manual 42 00:02:29,069 --> 00:02:33,839 pages installed on our Linux distribution. 43 00:02:34,769 --> 00:02:38,069 There are, there could be more, there could be 2, 3, 4, 44 00:02:38,099 --> 00:02:41,459 or 5, depending on what type of command it is 45 00:02:41,459 --> 00:02:45,509 and what kind of description it has. Let's look at 46 00:02:45,509 --> 00:02:50,669 the next command. Let's say ls --help. 47 00:02:50,669 --> 00:02:52,679 [No audio] 48 00:02:52,679 --> 00:02:55,289 See, there you go. It gives you a little longer 49 00:02:55,289 --> 00:02:59,519 description of your ls command. And it tells you 50 00:02:59,549 --> 00:03:02,189 all the different options that are associated with 51 00:03:02,219 --> 00:03:04,889 ls command. So of course right here, that's where 52 00:03:04,889 --> 00:03:08,519 it starts, and it goes all the way down, it tells you 53 00:03:08,519 --> 00:03:12,029 -a option, -A uppercase option, and so on. 54 00:03:12,929 --> 00:03:17,729 We could also run chmod --help. Remember 55 00:03:17,729 --> 00:03:21,719 chmod command is the change mode command to 56 00:03:21,719 --> 00:03:24,149 change the permission of a file. So when we do 57 00:03:24,149 --> 00:03:27,929 help, we're going to see it tells you, gives you 58 00:03:27,929 --> 00:03:30,989 quick description starting from here. It tells you 59 00:03:31,229 --> 00:03:35,773 that change the mode of each FILE to that of RFILE. 60 00:03:35,773 --> 00:03:39,299 Change the mode of each FILE to MODE, and a few 61 00:03:39,299 --> 00:03:43,229 different options. Same thing you run this command 62 00:03:43,229 --> 00:03:47,503 with other different command --help, 63 00:03:47,503 --> 00:03:49,559 it will give you the information 64 00:03:49,559 --> 00:03:52,079 about that command. Now the last one we're going 65 00:03:52,079 --> 00:03:55,709 to look at is the man command. man stands for 66 00:03:55,709 --> 00:03:59,099 manual and then space, let's say ls, and you run 67 00:03:59,099 --> 00:04:02,009 this command. There you go. It will give you a 68 00:04:02,009 --> 00:04:07,499 very nice descriptive way, a nice formatted way of 69 00:04:07,529 --> 00:04:11,249 for the user command information, tells you the 70 00:04:11,249 --> 00:04:14,579 name, the synopsis, the description and each 71 00:04:14,609 --> 00:04:20,819 option of the command. You could do space to go on 72 00:04:20,849 --> 00:04:24,149 each page, hit spacebar spacebar every time you 73 00:04:24,149 --> 00:04:26,548 want to quit out, just hit Q and you're going to be 74 00:04:26,579 --> 00:04:29,459 out of it. Same thing when you do a man command 75 00:04:29,459 --> 00:04:33,989 and then pwd, you do enter, and you're going to see 76 00:04:33,989 --> 00:04:37,139 the exact same thing. pwd print name of the 77 00:04:37,139 --> 00:04:39,689 current working directory and what other options 78 00:04:39,689 --> 00:04:43,709 it has. My favorite command, in all those help 79 00:04:43,709 --> 00:04:46,859 commands is this man command because it has 80 00:04:47,069 --> 00:04:51,539 exactly the information, the detailed information of each command. 81 00:04:51,539 --> 00:05:02,101 [No audio]