1 00:00:00,240 --> 00:00:01,200 In this video, 2 00:00:01,200 --> 00:00:03,480 we're going to discuss how to create, modify, 3 00:00:03,480 --> 00:00:05,280 and delete user groups. 4 00:00:05,280 --> 00:00:08,460 In order to gain access to users in a more efficient manner, 5 00:00:08,460 --> 00:00:11,190 you'll need to create groups for users to be a part of. 6 00:00:11,190 --> 00:00:13,560 This means that groups associate user accounts 7 00:00:13,560 --> 00:00:15,450 that have similar security requirements, 8 00:00:15,450 --> 00:00:17,850 and we can then assign rights and permissions to the groups 9 00:00:17,850 --> 00:00:20,550 instead of directly to the individual users. 10 00:00:20,550 --> 00:00:22,050 Just like user accounts, 11 00:00:22,050 --> 00:00:25,110 groups can also be modified and deleted when needed. 12 00:00:25,110 --> 00:00:27,090 Groups simplify administrative tasks, 13 00:00:27,090 --> 00:00:30,390 and they're represented on a system by a group ID number. 14 00:00:30,390 --> 00:00:33,510 Users can also be a member of more than one group. 15 00:00:33,510 --> 00:00:35,460 For example, on my network, 16 00:00:35,460 --> 00:00:37,410 I'm a member of the administrator's group. 17 00:00:37,410 --> 00:00:39,180 I'm also a member of the instructor's group 18 00:00:39,180 --> 00:00:40,380 and the accounting group, 19 00:00:40,380 --> 00:00:42,210 because I fill all these various work roles 20 00:00:42,210 --> 00:00:44,760 and responsibilities within my company. 21 00:00:44,760 --> 00:00:45,930 As an administrator, 22 00:00:45,930 --> 00:00:49,470 you're commonly going to reference the /etc/group file 23 00:00:49,470 --> 00:00:51,870 to find information about groups on your system, 24 00:00:51,870 --> 00:00:54,930 because it's the storage location for all of the groups. 25 00:00:54,930 --> 00:00:57,570 Each group is going to contain four fields of information 26 00:00:57,570 --> 00:00:59,100 separated by a colon. 27 00:00:59,100 --> 00:01:00,900 First, you have a Group Name. 28 00:01:00,900 --> 00:01:02,940 Second, you have a Password. 29 00:01:02,940 --> 00:01:04,800 Third, you have the Group ID. 30 00:01:04,800 --> 00:01:07,200 And fourth, you have the Group List. 31 00:01:07,200 --> 00:01:08,340 The group name refers 32 00:01:08,340 --> 00:01:10,410 to the user friendly name of the group. 33 00:01:10,410 --> 00:01:13,140 For example, you might find a group called instructors 34 00:01:13,140 --> 00:01:14,970 on my company system. 35 00:01:14,970 --> 00:01:17,070 The password field refers to the password 36 00:01:17,070 --> 00:01:19,350 that's being required to enter this group. 37 00:01:19,350 --> 00:01:21,600 The group ID refers to the reference number 38 00:01:21,600 --> 00:01:23,490 of the system for the group. 39 00:01:23,490 --> 00:01:25,080 And then we have the group list, 40 00:01:25,080 --> 00:01:26,790 and this refers to the group members 41 00:01:26,790 --> 00:01:28,590 that are part of this group. 42 00:01:28,590 --> 00:01:30,840 By default, the group list will be empty, 43 00:01:30,840 --> 00:01:34,440 because a new group has no members when you first create it. 44 00:01:34,440 --> 00:01:37,230 Now, the proper way to edit the /etc/group file 45 00:01:37,230 --> 00:01:41,250 is to use the groupadd, groupmod, or groupdel commands. 46 00:01:41,250 --> 00:01:43,680 The groupadd command is going to create the group. 47 00:01:43,680 --> 00:01:47,610 By default, the group has no members and no password. 48 00:01:47,610 --> 00:01:50,490 Then we have some groupadd options that we can use. 49 00:01:50,490 --> 00:01:52,680 This will allow us to modify this group. 50 00:01:52,680 --> 00:01:54,750 Now by using the option -g, 51 00:01:54,750 --> 00:01:55,680 you can create a group 52 00:01:55,680 --> 00:01:58,200 with a friendly name or a group ID. 53 00:01:58,200 --> 00:02:00,030 By using the -f option, 54 00:02:00,030 --> 00:02:01,770 you can exit with a success status 55 00:02:01,770 --> 00:02:03,750 if the group already exists. 56 00:02:03,750 --> 00:02:05,460 If you use the -o option, 57 00:02:05,460 --> 00:02:07,050 this is used to allow a group to be created 58 00:02:07,050 --> 00:02:09,270 with a non-unique group ID. 59 00:02:09,270 --> 00:02:11,280 The proper way to use the groupadd command 60 00:02:11,280 --> 00:02:13,710 is to enter groupadd, your options, 61 00:02:13,710 --> 00:02:15,390 and then your group name. 62 00:02:15,390 --> 00:02:19,620 For example, I could enter groupadd -g 100 instructors. 63 00:02:19,620 --> 00:02:22,770 This will create a new group called instructors. 64 00:02:22,770 --> 00:02:26,790 Manually editing the /etc/group file is not recommended, 65 00:02:26,790 --> 00:02:28,470 because a typo or other mistake 66 00:02:28,470 --> 00:02:30,930 could render your system unusable. 67 00:02:30,930 --> 00:02:34,260 Instead, you should modify it using the groupmod command. 68 00:02:34,260 --> 00:02:36,960 This will allow you to change the group's own attributes. 69 00:02:36,960 --> 00:02:40,140 By typing -g, you can change the group ID. 70 00:02:40,140 --> 00:02:42,930 By typing -n, you can rename the group. 71 00:02:42,930 --> 00:02:45,090 The proper way to use the groupmod command 72 00:02:45,090 --> 00:02:49,080 is to type groupmod, your options, and then your group name. 73 00:02:49,080 --> 00:02:51,180 Over time, you may find that you need to delete 74 00:02:51,180 --> 00:02:52,786 some of your older groups. 75 00:02:52,786 --> 00:02:55,050 The groupdel command can be used to delete the groups 76 00:02:55,050 --> 00:02:56,670 that you no longer need. 77 00:02:56,670 --> 00:02:58,440 Note though, the groupdel command 78 00:02:58,440 --> 00:03:00,870 will not delete the user accounts that are members 79 00:03:00,870 --> 00:03:02,400 of those groups being deleted. 80 00:03:02,400 --> 00:03:04,860 It only deletes the group itself. 81 00:03:04,860 --> 00:03:06,750 Always be careful when you're deleting groups, 82 00:03:06,750 --> 00:03:09,330 because a mistake here can cause the users of the groups 83 00:03:09,330 --> 00:03:11,370 to no longer be able to access resources 84 00:03:11,370 --> 00:03:13,320 that they need to do their jobs. 85 00:03:13,320 --> 00:03:14,850 The proper way to delete a group 86 00:03:14,850 --> 00:03:17,100 is by entering groupdel, the options, 87 00:03:17,100 --> 00:03:18,300 and then the group name.