Listing all linux users

3 Ways to List Users in Linux

Today different Operating Systems have the capability to use multiple users, each one with their settings and custom configurations to make things easier for administrators and operators to work in together on the same system.

Linux on the other hand is very strong on this matter as it allows multiple users to work at the same time on the system in an independent way. It can even allow a single user to open several sessions even from different locations in order to work on the system.

Here are some hints & tricks to handle users in Linux.

List all the users on Linux

Let’s say you want to create a sudo user in Linux. Probably, the very first thing to know is how to know what users are in my system. There are several ways you can obtain the list of users in Linux.

1. Show users in Linux using less /etc/passwd

This command allows sysops to list the the users that are locally stored in the system. It will give the listing in structured way as:

The structure in the above output goes as:

• User name
• Encrypted password ( x represents password is stored)
• User ID number (UID)
• User’s group ID number (GID)
• Full name
• User’s home directory
• User’s Login shell (default is bash shell)

Why so many users? Which ones are ‘real’?

The list shows a lot more users than you expected because it lists all the system users too.

Now if you want to distinguish the normal users from the system users, you can refer to the User identifier (UID) number.

Generally, a normal user has UID greater or equal to 1000. This gives you a hint that the user with UID >=1000 is a normal user and users with UID

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How To List All Users In Linux

This brief guide explains how to list all users in Linux operating systems. Before getting into the topic, we will see what is /etc/passwd file. Because we depend on this file through out this guide.

A brief note about the /etc/passwd file

In Linux (and Unix in general), the basic information about each user account is stored in «/etc/passwd» file. It is nothing but a plain text file that contains the attributes of all user accounts present in a Linux system.

By default, this file is readable by all users with the help of any text or graphical programs, such as Vi, Nano, Gedit etc or with commands like «cat«.

If you open this file..

. you will see several entries like below:

Each line in the /etc/passwd file represents a single user. The root user will be listed on the top. Each line contains seven attributes or fields separated by a colon without any spaces between each field. The name of the seven fields are given below:

1. Name

The «name» field is the user’s login name that you use to login to your Linux box.

2. Password

The «password» field merely contains a letter X. Meaning — the password is encrypted and stored in a separate file called «/etc/shadow» for security purpose. The /etc/shadow can not be read by the normal users. Here the X indicates that the user has a password. If this field is empty, the user has no password, so he can login without password.

3. User ID

The «User ID» (or UID in short) indicates the user’s unique numeric identification number. The root account’s UID is 0 (zero). The numbers from 1 to 99 are reserved for system accounts. And the numbers starting from100 to 999 are reserved for normal users and groups.

4. Group ID

The «Group ID» (or GID in short) indicates the primary group identifier the user belongs to. The GID is usually the same as the UID.

5. Geckos

The «geckos» field contains the general information of a user. For example, It may contain the user’s real name. This filed might be either empty separated by two colons or it might contain multiple entries separated by commas.

6. Home directory

The «home directory» field indicates the full path of the user’s home directory, for example /home/sk. This is the directory that the user is first in when he logged into a system. The home directory usually contains programs and configurations files belonged to the user.

7. Shell

The last filed is «shell». It indicates the full path of the default shell for that user.

Now, let us take the following line as an example:

In the above line,

• root — is the user name,
• x — indicates the root user has password,
• 0 — The first 0 (zero) indicates the UID,
• 0 — The second zero indicates the GID,
• root — It indicates the real name of the user.
• /root — It is the home directory of the root user,
• /bin/bash — Default shell for root user.

Hope you get a basic idea about the /etc/passwd file. Now let us get back to our topic i.e listing all users in a Linux system.

List All Users In Linux

There are couple ways to list all users in a Linux system. Here I have included all possible ways.

1. List all users in Linux using cat command

As the names says, the cat command is generally used to concatenate files and print the contents of the files.

To list all users in a Linux system using cut command, run:

This command will list all available users

Sample output:

List all users in Linux using cat command

As I mentioned already, the first field in the above entries represents the users. If you don’t want all fields but only display the user names, the following methods would help.

3. List users using cut command

The «cut» command is used to remove sections (or fields) from each line of files.

To list all users with cut command in a Linux system, run:

This command will only display the user names from the /etc/passwd file and ignore all other fields.

Sample output:

List all users in Linux using cut command

4. Print users in Linux with awk command

We can also use «awk» command to list all users in Linux.

This command will also display only the users and omit all other details.

List all users in Linux using awk command

5. View list of users with compgen

Compgen is BASH built-in to manipulate the programmable completion facilities.

To list all users using compgen, run:

6. Display all users using getent command

Another way to list the users in Linux is to use «getent» command like below:

This command will read the /etc/passwd file and lists all users in that file.

List all users in Linux using awk command

One notable advantage of getent command is it not only lists the users in the /etc/passwd file but all users in all configured userdb backends, for example LDAP, on a given system.

7. List users using the «more» or «less» commands

The more and less commands are used to open a given file for interactive reading, allowing scrolling and search.

To print all users using more or less command, run:

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Linux List All Users In The System Command

Table of contents

Linux list all users account using the /etc/passwd file

In order to list all users on Linux, use the cat command as follows:
$ cat /etc/passwd
Here is what I see:

Each line in the file has seven fields as follows. For example, consider the following line:
vnstat:x:131:137:vnstat daemon. /var/lib/vnstat:/usr/sbin/nologin
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• vnstat – The user name or login name.
• x – Encrypted password is stored in the /etc/shadow file.
• 131 – UID (user ID number)
• 137 – Primary GID (group ID number)
• vnstat daemon – GECOS. It may includes user’s full name (or application name, if the account is for a program), building and room number or contact person, office telephone number, home telephone number and any other contact information.
• /var/lib/vnstat – Home directory for the user.
• /usr/sbin/nologin – Login shell for the user. Pathnames of valid login shells comes from the /etc/shells file.

How to list users in Linux using pagers

Of course we can use pagers such as more/less commands as follows to view the /etc/passwd file:
$ more /etc/passwd
$ less /etc/passwd
Sample outputs:

Fig.01: List users using /etc/passwd

Linux list user names only

To list only usernames type the following awk command:
$ awk -F’:’ ‘< print $1>‘ /etc/passwd
Sample outputs:

Another option is to use the cut command:
$ cut -d: -f1 /etc/passwd

Get a list of all users using the getent command

To get a list of all Linux users you can type the following getent command:
$ getent passwd
$ getent passwd | grep tom
## get a list all users ##
$ getent passwd | cut -d: -f1
## count all user accounts using the wc ##
$ getent passwd | wc -l
One can use the compgen command on Linux to list users and other resources too:
$ compgen -u

Find out whether a user account exists in the Linux server

We can use above commands to see whether a user exists in the Linux machine as follows using the grep command:

A simplified command would be:

How to count user accounts in the Linux server

Want to get user accounts count on your system? Try the wc command as follows:
$ compgen -u | wc -l
$ getent passwd | wc -l

A Note About System and General Users

Each user has numerical user ID called UID. It is defined in /etc/passwd file. The UID for each user is automatically selected using /etc/login.defs file when you use useradd command. To see current value, enter:
$ grep «^UID_MIN» /etc/login.defs
$ grep UID_MIN /etc/login.defs
Sample outputs:

1000 is minimum values for automatic uid selection in useradd command. In other words all normal system users must have UID >= 1000 and only those users are allowed to login into system if shell is bash/csh/tcsh/ksh etc as defined /etc/shells file. Type the following command to list all login users:

To see maximum values for automatic uid selection in the useradd command, enter:
$ grep «^UID_MAX» /etc/login.defs
Sample outputs:

In other words, all normal system users must have UID >= 1000 (MIN) and UID /etc/shells file. Here is an updated code to get details:

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15+ examples for listing users in Linux

In this post, you will learn about listing users in Linux. Besides this, you will know other tricks about Linux users’ characteristics.

There are two types of users in Linux, system users who are created by default with the system. On the other hand, there are regular users who are created by system administrators and can log in to the system and use it.

Table of Contents

What file contains the list of the users on Linux?

Before we start listing users, we need to know where these users saved on Linux?

The users are stored in a text file on the system called the passwd file. This file is located in the /etc directory.

The file is located on the following path:

In this file, you can find all the information about the users in the system.

List all users

Listing users is the first step to manage them. This way, we will know how many they are and who they are. In Linux, almost everything can be done in various ways, and this is no exception.

To list all users, you can use the cat command:

As you can see in the image, there is all the information about the users.

1- In the first field, you will see the user name.

2- The second field (The x character) is a representation of the encrypted password. The encrypted password is stored in /etc/shadow file.

3- The UID or the user ID.

4- The next field refers to the primary group of the user.

5- Then, it shows user ID info such as the address, email, etc.

6- After this, you will see the home directory of the user.

7- The last field is the shell used by that user.

However, although the information is quite useful, if you only want to list users’ names in a basic way, you can use this command:

Now we have the names only by printing the first field of the file only.

List & sort users by name

The above command serves the purpose of listing users on Linux. But what about listing the users in alphabetical order?

To do this, we will use the previous command, but we will add the sort command.

So, the command will be like this:

As you can see in the image, the users are shown sorted.

Linux list users without password

It is important to know users who have no password and to take appropriate action. To list users who do not have a password, just use the following command:

The used regex will list all users with no password.

List users by disk usage

If you have a big directory and you want to know which user is flooding it, you can use the du command to get the disk usage.

With this, you can detect which of these users are misusing the disk space.

For it, it is enough to use the following command:

In this way, you will have the users ordered by the disk usage for the /home directory.

We used the -n for the sort command to sort the output by numbers.

List the currently logged users

To list the currently logged in users, we have several ways to do it. The first method we can use the users command:

It will list the users with open sessions in the system.

But this information is a little basic; however, we have another command that gives more details. The command is simply w.

With this command, we can have more information, such as the exact time when the session was started and the terminal session he has available.

Finally, there is a command called who. It is available to the entire Unix family. So you can use it on other systems like FreeBSD.

With who command, we also have some information about currently logged in users. Of course, we can add the option -a and show all the details.

This way, you know everything about the logged in users.

Linux list of users who recently logged into the system

We saw how to get the currently logged in users, what about listing the login history of users?

You can use the last command to get more info about the logins that took place:

Or the logins of a particular user

These are the user login activity and when it was started and how long it took.

List users’ logins on a specific date or time

What about listing users’ logins on a specific date or time? To achieve this, we use the last command but with the -t parameter:

And now, all you have to do is choose an exact date & time to list who logged at that time.

List all users in a group

There are two ways to list the members of a group in Linux, the easiest and most direct way is to get the users from the /etc/group file like this:

This command will list users in the likegeeks group.

The other way is by using commands like the members command in Debian based distros. However, it is not installed by default in Linux distributions.

To install it in Ubuntu / Linux Mint 19, just use APT:

Or in the case of CentOS:

Once it’s installed, you can run the command then the name of the group you want to list the users to:

This way, you can list users for a group in a Debian based distro. What about a RedHat based distro like CentOS?

You can use the following command:

List users with UID

In Unix systems, each user has a user identifier or ID. It serves to manage and administer accounts internally in the operating system.

Generally, UIDs from 0 to 1000 are for system users. And thereafter for regular users. Always on Unix systems, UID zero belongs to the root users (You can have more than one user with UID of zero).

So now, we will list the users with their respective UID using Awk.

The command that performs the task is the following:

As you can see, each user with his UID.

List root users

In a Unix-like system like Linux, there is usually only one root user. If there are many, how to list them?

To do this, we can use this command:

Here we are filtering the file to get users with UID of zero (root users).

Another way by checking the /etc/group file:

Here we are getting users in the group root from the /etc/group file.

Also, you can check if any user can execute commands as root by checking the /etc/sudoers file:

Get the total number of users

To get the total number of users in Linux, you can count lines in /etc/passwd file using the wc command like this:

Great! 43 users. But this includes system and regular users. What about getting the number of regular users only?

Easy! Since we know from above that regular users have UID of 1000 or greater, we can use Awk to get them:

List sudo users

Linux systems have a utility called sudo that allows you to execute commands as if you were another user who is usually the root user.

This should be handled with care in a professional environment.

Also, it is very important to know which users can run the sudo command. For this, it is enough to list the users that belong to the sudo group.

Users in this group can execute commands as super users.

List users who have SSH access

SSH allows users to access remote computers over a network. It is quite secure and was born as a replacement for Telnet.

By default, all regular users can log in and use SSH. If you want to limit this, you can use the SSH configuration file (/etc/ssh/ssh_config) and add the following directive:

Also, you can allow groups instead of allowing users only using the AllowGroups directive:

These directives define who can access the service. Don’t forget to restart the SSH service.

List users who have permissions to a file or directory

We can give more than one user permission to access or modify files & directories in two ways.

The first method is by adding users to the group of the file or the directory.

This way, we can list the group members using the members utility as shown above.

Okay, but what if we just want this user to have access to this specific file only (Not all the group permissions)?

Here we can set the ACL for this file using setfacl command like this:

Here we give the user called newser the permission for the file called myfile the permissions of read & write & execute.

Now the file can be accessed or modified by the owner, and the user called newuser. So how to list them?

We can list them using the getfacl command like this:

This command will list all users who have permissions for the file with their corresponding permissions.

List locked (disabled) users

In Linux, as a security measure, we can lock users. This as a precaution if it is suspected that the user is doing things wrong, and you don’t want to completely remove the user and just lock him for investigation.

To lock a user, you can use the following command:

Now the user named myuser will no longer be able to login or use the system.

To list all locked users of the system, just use the following command:

This will print all locked users, including system users. What about listing regular users only?

As we saw above, using Awk, we can get locked regular users like this:

Listing remote users (LDAP)

Okay, now can list all system users (local users), but what about remote users or LDAP users? Well, we can use a tool like ldapsearch, but is there any other way?

Luckily yes! You can list local & remote users with one command called getent

This command lists both local system users and LDAP or NIS users or any other network users.

You can pipe the results of this command to any of the above-mentioned commands the same way.

Also, the getent command can list group accounts like this:

You can check the man page of the command to know the other databases the command can search in.

Conclusion

Listing users in the Linux system was fun! Besides this, we have learned some tips about users and how to manage them in different ways.

Finally, this knowledge will allow a better administration of the users of the system.

I hope you find the tutorial useful. Keep coming back.

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Tutorial requirements
Requirements	Linux
Root privileges	No
Difficulty	Easy
Est. reading time	5 mintues