In Linux or Unix-like operating system, the ‘/etc/passwd’ file stores all user information. This file contains the normal (regular) and system users.
In this tutorial, I will show you how to list users in Linux using the command line.
The commands that I have listed below would work on all Linux distros like Ubuntu/Centos and Arch Linux.
1) From «/etc/passwd — Using Cut & Awk Command
As mentioned above the file /etc/passwd stores all users list regardless of created account for a human, service associated account or system functional user. Each line of /etc/passwd is a distinct user. These commands should work on Centos/Ubuntu/Arch and other Linux distros as well.
Use below command to list all user
you get the list without un-necessary information by using,
Here cut command is used to extract 1st field from the file named ‘/etc/passwd’ using the delimiter (;) and display required output on the console
Remember, cut command needs option otherwise it gives error.
Let’s try something more,
Now what we have done is, we have piped the previous command output to another variable «cut»
-d defines delimiter «:» -f1 display first field of line i.e. username.
Let us try some more formatting using Awk utility. This tool enables a system administrator to build commands that define text patterns that need to be searched in a file.
The following awk command will list all users with full name and home directory along with the login,
look at the output, you will see a well-formatted and decorated output.
The following command will list all users including system and regular (normal) users:
To list all regular user (only)
Linux systems keep ‘system’ accounts below a specific user id, so use awk search for UIDs higher than certian limit.
2) Getent command
The getent command do the same like cut command we have seen before, getent command fetches entries from databases supported by the Name Service library. If one or more options are provided to command, then only the entries that match the option will be displayed. Otherwise, all entries will be displayed. the syntax for getting end command,
Display all Users
This is same as that of listing users using cat /etc/passwd, if no other options are provided the getent command uses passwd as database reference and lists all users.
The below commands list all group without any condition or matches if no other options are provided the getent command uses group as database reference and lists all groups.
Search All groups with specific user
The above command fetches all group, passing username to pipe lists only matching row. The output has a group and username belonging to that group.
The below command is for advanced formatting using awk, cut & sed command together to list all users and users belongs to specific group.
Read Also:
Keep loving and liking our post, and comment more commands you know for listing users in different ways.
Источник
Linux List All Users In The System Command
Tutorial requirements
Requirements
Linux
Root privileges
No
Difficulty
Easy
Est. reading time
5 mintues
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 Where,
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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:
Источник
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
Источник
How to List Users in Linux, List all Users Command
Home » SysAdmin » How to List Users in Linux, List all Users Command
Linux OS is unique because of its multi-user characteristic allowing multiple users on one system, at the same time. However, tracking all users is essential.
In this article, earn multiple commands to list all Linux users along with their login information. These commands work on CentOS, Ubuntu, Arch Linux, and other Linux distributions as well.
A Linux distribution installed and running
A user with sudo privileges
Access to a terminal/command line
List All Linux Users, 2 Options
List All Users in Linux with the /etc/passwd File
Details of local users can be found in the /etc/passwd file. Every line contained in the file contains the information of one user.
There are two options.
Open the etc/passwd file by typing the command:
Alternatively, you can use the less command:
Note: To display a list of the logged-on users and the information such as boot time, processes, hostnames, and more, use the who command.
List All Linux Users with the getent Command
Database entries configured in the /etc/nsswitch.conf file include the passwd database with all the usernames and login information.
To extract this data, use the command:
Both Option 1 and Option 2 will display all the users and their login information.
Each line represents one user and has seven (7) fields.
The fields are separated by : (colons) and each line includes the following information:
1. Username 2. The encrypted password (represented by x, located in the /etc/shadow file) 3. User ID number (known as UID) 4. User group ID (known as GID) 5. User full name 6. User home directory 7. The login shell (by default set to bin/bash)
How to Only List Linux Usernames
In case you don’t need all the information related to each user, you can list only the usernames on the system. There are two ways to see just the first field (the username) of each user.
Option 1: Using the awk or cut command.
To list usernames only, you can use either of the following two (2) commands:
Option 2: Using the getent command with awk and cut .
To read and display the username without any additional information using the getent command, run the following command:
Alternatively, use the command:
How to Search for Existing Linux Users
The getent command also allows you to check whether a user is present on the system.
Any of the following two commands will provide you with that information:
If the user exists, it will display login information. On the other hand, if there is no such user, there will be no output.
For example, in the image below, the query displays whether a user named example exists. The output proves that such a user exists.
System User vs Normal User
A system user is the one that creates normal users. Therefore, in this instance, the system user is the root. This user is created when you first install the Linux operating system. Additionally, you can create system users for particular applications.
On the other hand, normal users are all users that the root (or a user with sudo privileges) creates. Each normal and system user has a real login shell, home directory, as well as a user ID (UID) number. The user ID number is given automatically in the range between the minimum and maximum values.
How to Check UID_MIN and UID_MAX
If you want to check what the UID range for normal users is, use grep with the following command:
The output shows that all normal users have a UID anywhere from 1000 (UID_MIN) to 6000 (UID_MAX).
Note: Change the values in the command according to the minimum and maximum UID values for your system.
How to List Normal Users
With these numbers in mind, you ask for a list of all the users in that range with the command:
The query lists all the normal users, as seen in the image below. In this example, there are two normal users in the specified range.
After reading this guide, you should know how to list all Linux users, search for users, and find the number of Linux users in any Linux distribution ( Ubuntu, CentOS, RHEL, Debian, and Mint).
