1 00:00:00,570 --> 00:00:01,589 In this lesson, 2 00:00:01,589 --> 00:00:04,650 we're going to discuss the Linux Directory Structure. 3 00:00:04,650 --> 00:00:06,240 Now, you need to become familiar 4 00:00:06,240 --> 00:00:07,650 with the structure and design 5 00:00:07,650 --> 00:00:11,280 of a typical Linux file system from a user's perspective. 6 00:00:11,280 --> 00:00:14,550 That way, you'll be able to easily navigate the file system 7 00:00:14,550 --> 00:00:16,440 and find the data and system files 8 00:00:16,440 --> 00:00:19,050 that you're looking for at any given time. 9 00:00:19,050 --> 00:00:22,170 Linux contains regular files that includes text files, 10 00:00:22,170 --> 00:00:24,390 executable files or programs, 11 00:00:24,390 --> 00:00:27,120 input for programs and output from programs. 12 00:00:27,120 --> 00:00:29,430 Besides all of these, the Linux file system 13 00:00:29,430 --> 00:00:31,740 also consists of other types of files, 14 00:00:31,740 --> 00:00:35,100 including directories, special files, links, 15 00:00:35,100 --> 00:00:37,680 domain sockets and named pipes. 16 00:00:37,680 --> 00:00:40,860 Directories refer to a container for other files. 17 00:00:40,860 --> 00:00:43,110 Special files include system files 18 00:00:43,110 --> 00:00:45,600 that are stored in the /dev directory. 19 00:00:45,600 --> 00:00:47,340 Links make a file accessible 20 00:00:47,340 --> 00:00:50,250 in multiple parts of the system's file tree. 21 00:00:50,250 --> 00:00:53,250 Domain sockets provide inter-process networking 22 00:00:53,250 --> 00:00:56,370 that's protected by the file system's access controls, 23 00:00:56,370 --> 00:00:59,070 whereas name pipes are going to enable processes 24 00:00:59,070 --> 00:01:00,480 to communicate with each other 25 00:01:00,480 --> 00:01:02,610 without using network sockets. 26 00:01:02,610 --> 00:01:03,660 If you want to look at all these 27 00:01:03,660 --> 00:01:06,060 and learn more about the different types of files, 28 00:01:06,060 --> 00:01:09,060 you can type file [Options] and the file name 29 00:01:09,060 --> 00:01:11,580 to determine the type of file you're looking at. 30 00:01:11,580 --> 00:01:14,820 Now, every file has a name to describe what they contain 31 00:01:14,820 --> 00:01:16,950 and how they relate to other files. 32 00:01:16,950 --> 00:01:19,770 By using the right combination of characters in a file name, 33 00:01:19,770 --> 00:01:21,510 you can ensure that the files are unique 34 00:01:21,510 --> 00:01:23,280 and easy to recognize. 35 00:01:23,280 --> 00:01:25,530 Although file names may contain a space, 36 00:01:25,530 --> 00:01:27,600 convention on Linux systems dictates 37 00:01:27,600 --> 00:01:28,950 that the words in a file name 38 00:01:28,950 --> 00:01:30,960 are more frequently going to be demarcated 39 00:01:30,960 --> 00:01:34,260 by using a hyphen or an underscore instead of a space, 40 00:01:34,260 --> 00:01:37,380 as this makes it easier to manage on the command-line. 41 00:01:37,380 --> 00:01:41,010 For example, if I have the file auditfile.txt 42 00:01:41,010 --> 00:01:43,440 or audit_file.txt, 43 00:01:43,440 --> 00:01:45,360 both of those would be much more acceptable 44 00:01:45,360 --> 00:01:48,390 than audit file.txt. 45 00:01:48,390 --> 00:01:49,350 For somebody who's new 46 00:01:49,350 --> 00:01:51,360 to the command-line environment in Linux, 47 00:01:51,360 --> 00:01:52,860 you may find yourself wondering, 48 00:01:52,860 --> 00:01:55,170 why are there so many unusual directories 49 00:01:55,170 --> 00:01:56,580 and what are they all there for, 50 00:01:56,580 --> 00:01:58,140 and why are these things all organized 51 00:01:58,140 --> 00:01:59,550 the way that they are? 52 00:01:59,550 --> 00:02:01,620 Well, directories should be organized 53 00:02:01,620 --> 00:02:03,510 and which files should be stored where, 54 00:02:03,510 --> 00:02:04,950 is going to be really important. 55 00:02:04,950 --> 00:02:07,590 So distributions have created a single reference point 56 00:02:07,590 --> 00:02:08,970 from which to work. 57 00:02:08,970 --> 00:02:12,180 The file system hierarchy standard or FHS, 58 00:02:12,180 --> 00:02:14,130 is a collaborative document that specifies 59 00:02:14,130 --> 00:02:16,980 a set of guidelines for the names of files and directories 60 00:02:16,980 --> 00:02:20,010 and their locations on a given Linux system. 61 00:02:20,010 --> 00:02:23,100 As defined by the FHS, the top-most directory 62 00:02:23,100 --> 00:02:24,450 in a Linux file system 63 00:02:24,450 --> 00:02:26,910 is always going to be the root directory. 64 00:02:26,910 --> 00:02:30,240 This is indicated by a single forward slash. 65 00:02:30,240 --> 00:02:32,820 Below the root directory are various sub directories 66 00:02:32,820 --> 00:02:35,730 that are standardized as part of the FHS. 67 00:02:35,730 --> 00:02:36,930 There are a lot of directories 68 00:02:36,930 --> 00:02:38,177 inside of a Linux file system 69 00:02:38,177 --> 00:02:40,250 and so we're just going to cover some of them here. 70 00:02:40,250 --> 00:02:44,100 /bin is going to store essential command-line utilities 71 00:02:44,100 --> 00:02:45,690 and binary files. 72 00:02:45,690 --> 00:02:50,660 For example, /bin/ls is the binary for the ls command, 73 00:02:50,660 --> 00:02:53,310 /boot is going to store all the files 74 00:02:53,310 --> 00:02:55,910 that are necessary to boot up the Linux operating system. 75 00:02:55,910 --> 00:03:00,330 /dev is going to store hardware and software device drivers. 76 00:03:00,330 --> 00:03:02,730 This directory maintains a file system entry 77 00:03:02,730 --> 00:03:03,990 that's going to represent the devices 78 00:03:03,990 --> 00:03:05,460 that are connected to the system, 79 00:03:05,460 --> 00:03:08,070 for example, your hard drive or a printer. 80 00:03:08,070 --> 00:03:10,320 If I'm looking at your first hard drive, for example, 81 00:03:10,320 --> 00:03:13,800 that's going to be /dev/sda1 82 00:03:13,800 --> 00:03:15,570 and that indicates the first partition 83 00:03:15,570 --> 00:03:17,430 on the first hard disc. 84 00:03:17,430 --> 00:03:19,380 If you look at /etc, 85 00:03:19,380 --> 00:03:22,530 this directory is going to store basic configuration files, 86 00:03:22,530 --> 00:03:27,530 for example, you might have the /etc/samba/smb/conf file. 87 00:03:28,890 --> 00:03:31,290 This stores your Samba configuration data 88 00:03:31,290 --> 00:03:33,690 and allows you to use SMB on the network. 89 00:03:33,690 --> 00:03:35,730 If you look at the /home directory, 90 00:03:35,730 --> 00:03:37,740 this stores your users' home directories, 91 00:03:37,740 --> 00:03:39,900 including all of their personal files. 92 00:03:39,900 --> 00:03:43,290 The /lib directory stores shared program libraries 93 00:03:43,290 --> 00:03:44,700 that are required by the kernel, 94 00:03:44,700 --> 00:03:47,153 command-line utilities and other binaries. 95 00:03:47,153 --> 00:03:50,040 The /media directory is going to store mount points 96 00:03:50,040 --> 00:03:51,990 for removable media, such as CD ROMs, 97 00:03:51,990 --> 00:03:55,483 DVDs or even old school floppy discs. 98 00:03:55,483 --> 00:03:58,050 /mnt stands for mount. 99 00:03:58,050 --> 00:03:59,490 This refers to the mount point 100 00:03:59,490 --> 00:04:01,650 for temporary mounting file systems, 101 00:04:01,650 --> 00:04:04,890 for example, if I put a USB thumb drive into my system, 102 00:04:04,890 --> 00:04:07,670 I might mount it under the /mnt directory. 103 00:04:07,670 --> 00:04:12,510 /opt stores optional files for large software packages 104 00:04:12,510 --> 00:04:14,370 and this is our optional directory. 105 00:04:14,370 --> 00:04:16,920 These packages normally create a sub directory 106 00:04:16,920 --> 00:04:19,950 bearing their name underneath the /opt directory 107 00:04:19,950 --> 00:04:22,740 and then place their files in that sub directory. 108 00:04:22,740 --> 00:04:24,270 For example, if I installed 109 00:04:24,270 --> 00:04:26,130 the Nessus vulnerability scanner, 110 00:04:26,130 --> 00:04:28,540 I might see one that's called /opt/nessus 111 00:04:29,820 --> 00:04:33,240 and it contains all the files for this scanning program. 112 00:04:33,240 --> 00:04:36,480 Another directory we have is /proc, 113 00:04:36,480 --> 00:04:38,400 which is the process directory. 114 00:04:38,400 --> 00:04:41,130 This directory refers to a virtual file system 115 00:04:41,130 --> 00:04:43,950 that represents continuously updated kernel information 116 00:04:43,950 --> 00:04:46,500 to the user in a typical file format. 117 00:04:46,500 --> 00:04:49,920 For example, the /proc/mounts file 118 00:04:49,920 --> 00:04:52,940 is going to have all of our mounted information inside of it. 119 00:04:52,940 --> 00:04:57,564 /root is going to refer to the home directory of the root user. 120 00:04:57,564 --> 00:05:00,330 /sbin stores binaries that are used 121 00:05:00,330 --> 00:05:02,160 for completing the booting process 122 00:05:02,160 --> 00:05:05,130 and other ones that are going to be used by the root user, 123 00:05:05,130 --> 00:05:08,550 for example, /sbin/ifconfig 124 00:05:08,550 --> 00:05:11,430 is a file for the binary of the ifconfig command 125 00:05:11,430 --> 00:05:13,290 that's used to manage the network interfaces 126 00:05:13,290 --> 00:05:14,910 on a given system. 127 00:05:14,910 --> 00:05:17,700 Another directory we have is /sys 128 00:05:17,700 --> 00:05:20,130 and the sys is our system directory. 129 00:05:20,130 --> 00:05:22,110 It's going to be a virtual file system 130 00:05:22,110 --> 00:05:24,600 that stores information about devices, 131 00:05:24,600 --> 00:05:28,705 for example, /sys/block includes links to devices 132 00:05:28,705 --> 00:05:30,930 that are stored in various sub directories 133 00:05:30,930 --> 00:05:35,610 under the /sys/devices/location directories. 134 00:05:35,610 --> 00:05:37,500 And this presents as a hierarchy of devices 135 00:05:37,500 --> 00:05:39,300 inside of our kernel. 136 00:05:39,300 --> 00:05:42,180 The /temp directory is going to store temporary files 137 00:05:42,180 --> 00:05:44,880 that will be lost on system shutdown. 138 00:05:44,880 --> 00:05:48,030 The /usr directory is our user directory. 139 00:05:48,030 --> 00:05:49,083 It's a read-only directory 140 00:05:49,083 --> 00:05:51,330 that stores small programs and files 141 00:05:51,330 --> 00:05:53,490 that's accessible to all users. 142 00:05:53,490 --> 00:05:55,950 Finally, we have the /var directory 143 00:05:55,950 --> 00:05:57,510 which stores variable files 144 00:05:57,510 --> 00:05:59,880 or files that are expected to constantly change 145 00:05:59,880 --> 00:06:01,470 as the system is running. 146 00:06:01,470 --> 00:06:04,410 This includes things like log files, printer spools 147 00:06:04,410 --> 00:06:07,290 and some networking service configuration files. 148 00:06:07,290 --> 00:06:09,990 Now, I mentioned the /usr directory. 149 00:06:09,990 --> 00:06:10,846 This directory actually has 150 00:06:10,846 --> 00:06:13,290 some important sub directories too. 151 00:06:13,290 --> 00:06:17,190 The /usr/bin directory includes executable programs 152 00:06:17,190 --> 00:06:19,620 that can be executed by all users. 153 00:06:19,620 --> 00:06:23,610 The /usr/local directory includes custom-built applications 154 00:06:23,610 --> 00:06:25,396 that are stored here by default. 155 00:06:25,396 --> 00:06:29,520 /usr/lib includes object libraries and internal binaries 156 00:06:29,520 --> 00:06:31,728 that are needed for executable programs. 157 00:06:31,728 --> 00:06:36,600 /usr/lib64 has the same purpose as /usr/lib, 158 00:06:36,600 --> 00:06:38,970 except it's meant for 64 bit systems 159 00:06:38,970 --> 00:06:41,310 instead of older 32 bit systems. 160 00:06:41,310 --> 00:06:45,030 The /usr/share is going to include read-only architecture 161 00:06:45,030 --> 00:06:46,830 independent files that can be shared 162 00:06:46,830 --> 00:06:49,680 among different architectures of an operating system, 163 00:06:49,680 --> 00:06:52,740 for example, are we using an X86-based system 164 00:06:52,740 --> 00:06:56,040 or an X64 based system or an ARM-based system. 165 00:06:56,040 --> 00:06:58,020 All those things will be read-only 166 00:06:58,020 --> 00:06:59,730 and independent architecture files 167 00:06:59,730 --> 00:07:02,250 in this /usr/share directory. 168 00:07:02,250 --> 00:07:04,500 Now, another important directory is the home directory 169 00:07:04,500 --> 00:07:07,050 and I briefly mentioned it earlier in this lesson. 170 00:07:07,050 --> 00:07:09,660 The home directory contains a user's personal files 171 00:07:09,660 --> 00:07:13,170 or files that are otherwise specific to that user. 172 00:07:13,170 --> 00:07:14,880 The home directory is where you're placed 173 00:07:14,880 --> 00:07:17,070 when you log into the system initially. 174 00:07:17,070 --> 00:07:19,950 In Linux, by default, every single user 175 00:07:19,950 --> 00:07:22,680 except the root user, is assigned a sub directory 176 00:07:22,680 --> 00:07:24,390 under the /home. 177 00:07:24,390 --> 00:07:29,390 So if my username was Jason, I would be /home/jason. 178 00:07:29,640 --> 00:07:31,530 A user can create sub directories and files 179 00:07:31,530 --> 00:07:33,150 within their directory then, 180 00:07:33,150 --> 00:07:36,990 so I can have /home/jason/movies 181 00:07:36,990 --> 00:07:40,280 or /home/jason/downloads, 182 00:07:40,280 --> 00:07:43,860 /home/jason/documents. 183 00:07:43,860 --> 00:07:45,270 You get the idea here. 184 00:07:45,270 --> 00:07:46,680 Now, for the root user, 185 00:07:46,680 --> 00:07:48,060 they have a special home directory 186 00:07:48,060 --> 00:07:49,920 that's outside of the home directory. 187 00:07:49,920 --> 00:07:52,620 It's actually going to be at /root. 188 00:07:52,620 --> 00:07:54,630 Now, if you're going to be talking about a directory, 189 00:07:54,630 --> 00:07:56,400 you need to know where you are. 190 00:07:56,400 --> 00:07:58,650 What is your current working directory? 191 00:07:58,650 --> 00:08:00,810 As I said, when you first log in the system, 192 00:08:00,810 --> 00:08:03,420 you're usually going to be located in your home directory. 193 00:08:03,420 --> 00:08:07,110 So for me, that would be /home/jason. 194 00:08:07,110 --> 00:08:09,870 Now, this is known as your current working directory. 195 00:08:09,870 --> 00:08:11,299 This is the location on the system 196 00:08:11,299 --> 00:08:15,000 that you're accessing at any point in time right now. 197 00:08:15,000 --> 00:08:16,950 Now, there's two ways to talk about 198 00:08:16,950 --> 00:08:18,660 the current working directory. 199 00:08:18,660 --> 00:08:20,790 You can call it by the actual full name, 200 00:08:20,790 --> 00:08:24,300 like /home/jason for my home directory 201 00:08:24,300 --> 00:08:26,010 or you can also refer to it 202 00:08:26,010 --> 00:08:28,230 with a shorthand of a single period. 203 00:08:28,230 --> 00:08:30,510 So if I talk about just the dot directory, 204 00:08:30,510 --> 00:08:32,820 that is the current directory I'm in. 205 00:08:32,820 --> 00:08:34,049 Now, if you go one level 206 00:08:34,049 --> 00:08:35,970 above that current working directory, 207 00:08:35,970 --> 00:08:37,860 you have the parent directory. 208 00:08:37,860 --> 00:08:40,169 We call this the dot dot. 209 00:08:40,169 --> 00:08:42,510 All directories, except the root directory, 210 00:08:42,510 --> 00:08:44,370 have a parent directory. 211 00:08:44,370 --> 00:08:46,288 Now, you can use this double period notation 212 00:08:46,288 --> 00:08:48,780 to switch to your parent directory at any time. 213 00:08:48,780 --> 00:08:51,630 So if I was in /home/jason 214 00:08:51,630 --> 00:08:53,910 and I wanted to go to the /home directory. 215 00:08:53,910 --> 00:08:57,840 I could type in cd .. and hit ENTER. 216 00:08:57,840 --> 00:09:00,690 Now, I would be in the /home directory 217 00:09:00,690 --> 00:09:03,720 and if I wanted to talk about my current working directory, 218 00:09:03,720 --> 00:09:05,790 that would actually also be known as the dot. 219 00:09:05,790 --> 00:09:08,760 So my dot has now gone to being /home, 220 00:09:08,760 --> 00:09:11,070 because that's where I'm sitting right now. 221 00:09:11,070 --> 00:09:13,830 Now, when we talk about a path in a file system, 222 00:09:13,830 --> 00:09:16,200 we're talking about a specific location. 223 00:09:16,200 --> 00:09:17,130 Now, we always read this 224 00:09:17,130 --> 00:09:20,580 as starting out with the slash, which is the root directory. 225 00:09:20,580 --> 00:09:23,430 That is the directory at the top of the directory tree 226 00:09:23,430 --> 00:09:26,310 and then as we start talking about different directories, 227 00:09:26,310 --> 00:09:27,780 we start adding the words. 228 00:09:27,780 --> 00:09:30,450 So I mentioned we had the slash, that's the root, 229 00:09:30,450 --> 00:09:33,360 then we had the word home, that's the home directory 230 00:09:33,360 --> 00:09:35,730 which is the first directory under the root. 231 00:09:35,730 --> 00:09:39,120 If I wanted to talk about home/jason, 232 00:09:39,120 --> 00:09:41,580 that would actually be two directories down. 233 00:09:41,580 --> 00:09:43,950 We have the root directory, we have the home directory 234 00:09:43,950 --> 00:09:47,880 and then the Jason folder underneath that home directory. 235 00:09:47,880 --> 00:09:49,530 This is how we start talking about a path, 236 00:09:49,530 --> 00:09:54,240 so that full path becomes /home/jason. 237 00:09:54,240 --> 00:09:56,040 You can refer to a particular file 238 00:09:56,040 --> 00:09:57,466 by providing the path to that directory 239 00:09:57,466 --> 00:09:59,610 that contains the file. 240 00:09:59,610 --> 00:10:02,160 So if I want to refer to a file called my work 241 00:10:02,160 --> 00:10:03,750 and my documents folder, 242 00:10:03,750 --> 00:10:04,850 I will give you the full path, 243 00:10:04,850 --> 00:10:09,850 /home/jason/documents/mywork. 244 00:10:10,080 --> 00:10:12,480 Notice I'm using forward slashes here. 245 00:10:12,480 --> 00:10:15,090 In Windows, we tend to use back slashes 246 00:10:15,090 --> 00:10:18,390 and this is a key difference between Linux and Windows. 247 00:10:18,390 --> 00:10:19,920 Now, when we talk about the slash 248 00:10:19,920 --> 00:10:22,920 that precedes the home, that is that root directory. 249 00:10:22,920 --> 00:10:25,020 So if I have just a single forward slash, 250 00:10:25,020 --> 00:10:27,900 that is the root and everything else works its way 251 00:10:27,900 --> 00:10:31,470 from the root down to the particular file I'm working at. 252 00:10:31,470 --> 00:10:34,050 Now, there's also two ways to name these paths. 253 00:10:34,050 --> 00:10:35,640 You can use an absolute path, 254 00:10:35,640 --> 00:10:37,320 which is what I was just using 255 00:10:37,320 --> 00:10:39,510 or you can use a relative path. 256 00:10:39,510 --> 00:10:41,460 When I talk about an absolute path, 257 00:10:41,460 --> 00:10:43,560 this refers to the specific location 258 00:10:43,560 --> 00:10:46,080 irrespective of any current working directory 259 00:10:46,080 --> 00:10:47,670 or combined paths. 260 00:10:47,670 --> 00:10:49,350 These paths are usually written 261 00:10:49,350 --> 00:10:51,240 with reference to the root directory. 262 00:10:51,240 --> 00:10:53,160 So we're going to start with that forward slash 263 00:10:53,160 --> 00:10:54,720 and give all of the directories 264 00:10:54,720 --> 00:10:56,610 all the way down to that file. 265 00:10:56,610 --> 00:10:58,440 Now, anytime you have a path that doesn't begin 266 00:10:58,440 --> 00:10:59,730 with a forward slash, 267 00:10:59,730 --> 00:11:01,830 that is known as a relative path, 268 00:11:01,830 --> 00:11:04,050 and a relative path is the path relative 269 00:11:04,050 --> 00:11:06,120 to your current working directory. 270 00:11:06,120 --> 00:11:09,000 So instead of having the full absolute path, 271 00:11:09,000 --> 00:11:09,900 I wouldn't need that, 272 00:11:09,900 --> 00:11:13,710 I can just put the path to where I am to where I want to go. 273 00:11:13,710 --> 00:11:15,480 And we can do this by using the dot, 274 00:11:15,480 --> 00:11:17,820 which is the current working directory or the dot dot 275 00:11:17,820 --> 00:11:19,440 which goes up to the parent. 276 00:11:19,440 --> 00:11:20,850 So let's say I wanted to go 277 00:11:20,850 --> 00:11:22,560 and access the absolute location 278 00:11:22,560 --> 00:11:25,770 and I'm sitting inside of /home/jason 279 00:11:25,770 --> 00:11:28,830 and I want to get to the /usr/bin directory. 280 00:11:28,830 --> 00:11:30,930 I can do that by using an absolute path 281 00:11:30,930 --> 00:11:34,530 and typing in cd /usr/bin. 282 00:11:34,530 --> 00:11:37,830 Now, if I want to do that same thing using a relative path, 283 00:11:37,830 --> 00:11:42,830 I could do it by doing cd ../../usr/bin. 284 00:11:44,730 --> 00:11:46,440 And that would say to go up to directories 285 00:11:46,440 --> 00:11:47,700 from the Jason directory, 286 00:11:47,700 --> 00:11:49,860 to the home directory, to the root directory 287 00:11:49,860 --> 00:11:52,890 and then go down into user and into bin. 288 00:11:52,890 --> 00:11:56,340 This is how you can use absolute or relative paths. 289 00:11:56,340 --> 00:11:57,690 Now, after having a good sense 290 00:11:57,690 --> 00:11:59,730 of what a Linux directory structure looks like 291 00:11:59,730 --> 00:12:01,590 from this overview I provided you, 292 00:12:01,590 --> 00:12:03,480 one of the common things you'll need to know, 293 00:12:03,480 --> 00:12:05,790 is how these commands are used to navigate 294 00:12:05,790 --> 00:12:07,620 through the file structure. 295 00:12:07,620 --> 00:12:10,380 As we just showed, you can use the cd command 296 00:12:10,380 --> 00:12:12,090 to go through a directory structure 297 00:12:12,090 --> 00:12:14,460 using either absolute or relative pass 298 00:12:14,460 --> 00:12:16,590 to change your current working directory. 299 00:12:16,590 --> 00:12:18,600 If you want to list out all the files and directories 300 00:12:18,600 --> 00:12:20,250 in that current working directory 301 00:12:20,250 --> 00:12:23,430 or some relative or absolute path you specify, 302 00:12:23,430 --> 00:12:27,300 you can use the ls command, which lists all of those things. 303 00:12:27,300 --> 00:12:30,300 In a long form listing, you can use -l 304 00:12:30,300 --> 00:12:32,010 and this will also show you the first bit 305 00:12:32,010 --> 00:12:33,660 that indicates the type of file. 306 00:12:33,660 --> 00:12:36,570 Is it a file or is it a directory, for example? 307 00:12:36,570 --> 00:12:38,280 Also, if you're ever lost 308 00:12:38,280 --> 00:12:40,950 and you want to know what your current working directory is, 309 00:12:40,950 --> 00:12:43,380 you can use the command pwd. 310 00:12:43,380 --> 00:12:45,060 If you type in pwd, 311 00:12:45,060 --> 00:12:46,890 it's going to display your current working directory 312 00:12:46,890 --> 00:12:49,170 to the screen and I remember this by saying, 313 00:12:49,170 --> 00:12:52,650 my present working directory for pwd. 314 00:12:52,650 --> 00:12:54,990 All these are things you need to be comfortable with 315 00:12:54,990 --> 00:12:57,810 inside the command-line environment, using cd, 316 00:12:57,810 --> 00:13:00,063 using ls and using pwd.