Linux list all sudo users

Is there a command to list all users? Also to add, delete, modify users, in the terminal?

I need a command to list all users as well as commands to add, delete and modify users from terminal — any commands that could help in administrating user accounts easily by terminal.

10 Answers 10

To list

To list all local users you can use:

To list all users capable of authenticating (in some way), including non-local, see this reply.

Some more useful user-management commands (also limited to local users):

To add

To add a new user you can use:

sudo adduser new_username

sudo useradd new_username

To remove/delete

To remove/delete a user, first you can use:

Then you may want to delete the home directory for the deleted user account :

Please use with caution the above command!

To modify

To modify the username of a user:

usermod -l new_username old_username

To change the password for a user:

To change the shell for a user:

To change the details for a user (for example real name):

To add a user to the sudo group:

And, of course, see also: man adduser , man useradd , man userdel . and so on.

Radu forgot to mention sudo chfn which changes user details (for example real name). I tried to add this as a comment, but I got error telling me that I must have +50 reputation to do so.

I think that it should be underlined that the correct answer to the linked question is askubuntu.com/a/381646/16395 — otherwise you have to take into account the GID/UID Ubuntu policies by hand. The accepted answer is not so clear.

sudo userdel DOMAIN\\johndoe gives me the error: «userdel: cannot remove entry ‘DOMAIN\johndoe’ from /etc/passwd — I looked in /etc/passwd and they’re not even in there, likely because it’s a «domain» account?

@00fruX Yeah. If you’re using a centralised user database you’re going to need to deal with it directly.

Just press Ctrl + Alt + T on your keyboard to open Terminal. When it opens, run the command(s) below:

less /etc/passwd more /etc/passwd 

@nux A bit late to the party, but from command line use adduser instead, useradd should be limited to scripts where the author really really knows what he is doing.

The easiest way to get this kind of information is getent — see manpage for the getent command . While that command gives the same output as cat /etc/passwd it is useful to remember because it will give you lists of several elements in the OS.

To get a list of all users you type (as users are listed in /etc/passwd )

To add a user newuser to the system you would type

to create a user that has all default settings applied.

Bonus: To add any user (for instance anyuser) to a group (for instance cdrom) type

sudo adduser anyuser cdrom 

You delete a user (for instance obsolete) with

If you want to delete his home directory/mails as well you type

sudo deluser --remove-home obsolete 

sudo deluser --remove-all-files obsolete 

will remove the user and all files owned by this user on the whole system.

It’s useful to remember that getent doesn’t just print the output of users in /etc/passwd but all users in all configured userdb backends on a given system, whether it’s /etc/passwd or LDAP, etc.

@MarcinKaminski is right, it also prints users setup in SSO systems who have access to the server. this answer is the the best one, with getent passwd being the right command

This should get, under most normal situations, all normal (non-system, not weird, etc) users:

awk -F'[/:]' '= 1000 && $3 != 65534) print $1>' /etc/passwd 

• reading in from /etc/passwd
• using : as a delimiter
• if the third field (the User ID number) is larger than 1000 and not 65534, the first field (the username of the user) is printed.

This is because on many linux systems, usernames above 1000 are reserved for unprivileged (you could say normal) users. Some info on this here:

A user ID (UID) is a unique positive integer assigned by a Unix-like operating system to each user. Each user is identified to the system by its UID, and user names are generally used only as an interface for humans.

UIDs are stored, along with their corresponding user names and other user-specific information, in the /etc/passwd file.

The third field contains the UID, and the fourth field contains the group ID (GID), which by default is equal to the UID for all ordinary users.

In the Linux kernels 2.4 and above, UIDs are unsigned 32-bit integers that can represent values from zero to 4,294,967,296. However, it is advisable to use values only up to 65,534 in order to maintain compatibility with systems using older kernels or filesystems that can only accommodate 16-bit UIDs.

The UID of 0 has a special role: it is always the root account (i.e., the omnipotent administrative user). Although the user name can be changed on this account and additional accounts can be created with the same UID, neither action is wise from a security point of view.

The UID 65534 is commonly reserved for nobody, a user with no system privileges, as opposed to an ordinary (i.e., non-privileged) user. This UID is often used for individuals accessing the system remotely via FTP (file transfer protocol) or HTTP (hypertext transfer protocol).

UIDs 1 through 99 are traditionally reserved for special system users (sometimes called pseudo-users), such as wheel, daemon, lp, operator, news, mail, etc. These users are administrators who do not need total root powers, but who perform some administrative tasks and thus need more privileges than those given to ordinary users.

Some Linux distributions (i.e., versions) begin UIDs for non-privileged users at 100. Others, such as Red Hat, begin them at 500, and still others, such Debian, start them at 1000. Because of the differences among distributions, manual intervention can be necessary if multiple distributions are used in a network in an organization.

Also, it can be convenient to reserve a block of UIDs for local users, such as 1000 through 9999, and another block for remote users (i.e., users elsewhere on the network), such as 10000 to 65534. The important thing is to decide on a scheme and adhere to it.

Among the advantages of this practice of reserving blocks of numbers for particular types of users is that it makes it more convenient to search through system logs for suspicious user activity.

Contrary to popular belief, it is not necessary that each entry in the UID field be unique. However, non-unique UIDs can cause security problems, and thus UIDs should be kept unique across the entire organization. Likewise, recycling of UIDs from former users should be avoided for as long as possible.

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How To List All Sudo Users On Ubuntu

On Unix-like operating systems, sudo allows users to run programs with the same security privileges given to the superuser (also known as root , administrator , admin , or supervisor ). It originally meant «superuser do» because sudo was invented to run commands only as the superuser on older versions of Linux.

How do you list all the sudo users on a Ubuntu machine?

You can do this using the getent command:

The output should look something like this:

This command queries the /etc/group file in your system and gets each entry that matches sudo .

The output format is as follows:

Here’s an explanation for each item:

• group is the name of the given group.
• password is the encrypted group password. If this value is empty, it means there is no password. If the value is x , the password is in the /etc/gshadow file.
• GID is the group ID.
• users() is a comma-separated list of users that are members of the group. An empty value means there are no users in the group.

If you want to output only the list of usernames and remove the rest of the items, use this command:

This will output just the comma-delimited list of users:

Also, you may need to check if a specific user has sudo access or not.

You can do this by using the -l and -U options together in a single command:

If that user has sudo access, it will print the level of sudo access it has:

User bob may run the following commands on comp: (ALL : ALL) ALL 

If the user doesn’t have sudo access, it will output this:

User john is not allowed to run sudo on comp. 

There you go! That’s how you get a list of all the sudo users on a Ubuntu machine and check if a single user has sudo permissions.

Thanks for reading and happy computing!

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Как получить список пользователей, которым разрешено sudo?

Есть сервер с большим числом системных пользователей, имеющих доступ к нему по SSH. В рамках задачи по инвентаризации доступов необходимо получить список всех пользователей, которым на этом сервере разрешено становиться рутом через sudo . Понятно, что про единичного пользователя можно посмотреть вывод id username на предмет группы wheel (которая из коробки даёт в CentOS возможность становиться рутом через sudo ), но как бы получить список всех таких пользователей? Понятно, что можно написать цикл, в котором перебрать вывод id для всех пользователей системы, но можно ли сделать как-нибудь поизящнее?

2 ответа 2

универсальный способ получения списка пользователей указанной группы — с помощью программы getent, вызванной для базы данных group (баз данных много, смотрите в документации: $ man getent ):

$ getent group название-группы 

название-группы:x:1000:пользователь1,пользователь2,пользователь3 

чаще всего это просто строка из файла /etc/group , которую можно было получить и командой

$ grep '^название-группы:' /etc/group 

но далеко не всегда — ведь существуют разные механизмы аутентификации, хранящие данные совсем по-другому.

а по поводу глобального вопроса — получения списка пользователей, которым разрешено выполнение программы sudo, короткого, универсального и простого решения, насколько мне известно, нет. надо либо производить синтаксический разбора файлов /etc/sudoers* , либо, получив полный список пользователей от всех аутентификационных подсистем (с помощью $ getent passwd ), анализировать для каждого пользователя вывод команды (не будет работать на старых версиях программы sudo):

User пользователь is not allowed to run sudo on . 

Источник

How to Find All Sudo Users in Linux

Sudo users are privileged users who have more permissions to run commands & processes that regular users. As a system administrator, it is important to regularly keep track of all sudo users in Linux. In this article, we will learn how to find all sudo users in Linux. Sometimes you may have given sudo access temporarily to certain users to install applications or run administrative commands. If they are no longer required, it is advisable to find such sudo users and revoke the sudo access.

How to Find All Sudo Users in Linux

Here are the different ways to list sudo users in Linux.

1. List All Users

Here is the command to list all users in Linux.

/etc/password contains a list of all users in your system, along with their encrypted passwords. We will use awk command to parse this file and print the first column which is nothing but username.

Another simple ways to get this list of users in system is to use compgen command.

Next, you can run the following command to list all sudo users in Linux.

$ grep '^sudo:.*$' /etc/group | cut -d: -f4

All users belonging to sudo user group have sudo privileges. /etc/group file contains information about different groups and their members. We will use grep command to look for rows about sudo group in this file and pipe its output to cut command to extract only the username.

Alternatively, you can also use getent command to get the same output.

$ getent group sudo | cut -d: -f4

2. Find If User Has Sudo Privileges

We have seen how to list all sudo users in our system. Now if you want to check if a specific user has sudo privileges, you can use the following command.

Here is an example to check if user test_user is sudo user.

Matching Defaults entries for test_user on ubuntuserver: env_reset, mail_badpass, secure_path=/usr/local/sbin\:/usr/local/bin\:/usr/sbin\:/usr/bin\:/sbin\:/bin\:/snap/bin User test_user may run the following commands on ubuntuserver: (ALL : ALL) ALL

If your Linux user does not have sudo access, you will see the following message.

$ sudo -l -U test_user2 User test_user2 is not allowed to run sudo on ubuntuserver.

If you want to find if a logged in user(e.g test_user) has sudo privileges, you can run the following command.

If you don’t get any output, the user has sudo access.

If you don’t have sudo access, you will see the following message.

Sorry, user test_user may not run sudo on ubuntuserver.

In this article, we have learnt how to find all sudo users in out system, and also how to find if a given user has sudo privileges.

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