Information about users linux

How to check list of users in Unix

Command to check list of users in Unix

On a FreeBSD/OpenBSD/NetBSD and many other Unix-like system, just type the following cat command/more command/less command to get a list of all user accounts:
$ cat /etc/passwd
$ more /etc/passwd
$ less /etc/passwd
Sample outputs:

Understanding file format

Consider the last line:

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1. vnstat – User name
2. * – Encrypted password is stored in a in a separate file
3. 284 – UID (User id)
4. 284 – GID (Group id)
5. vnStat Network Monitor – General information about the user
6. /nonexistent – User’s home directory
7. /usr/sbin/nologin – User’s login shell

How to just display a list of user names

Use the cut command as follows:
$ cut -d: -f1 /etc/passwd
OR use awk command:
$ awk -F’:’ ‘< print $1>‘ /etc/passwd
Sample outputs:

How do I search for a given user name such as vivek

Use the grep command as follows:
$ grep ‘^userNameHere’ /etc/passwd
$ grep ‘^vivek’ /etc/passwd
Sample outputs:

How to use getent command to find out a list of users

To get entries from administrative database such as /etc/passwd use the getent command as follows:
$ getent passwd
$ getent passwd | more
$ getent passwd | grep vivek

A note about macOS Unix users

If you are using a macOS, try the following command to check list of users in Unix cli (open the Terminal app and type the following bash command):
$ dscl . list /Users
OR
$ dscacheutil -q user
The dscl is a general-purpose utility for operating on Directory Service directory nodes.

How to find which Unix users are logged in and what they are doing

How do I see available list of groups on my server?

Type any one of the following command:
$ more /etc/group
$ less /etc/group
$ grep vivek /etc/group

Display Unix account information using logins command

The logins command shows information about user and system accounts. All you have to do is type the following command:
$ logins

To get information about the password change and user account expiration times, run:
$ logins -a
Only find and display information about tom and jerry accounts:
$ logins -l userName
$ logins -l tom,jerry
Want to see Unix user accounts with no password? Pass the -p option:
$ logins -p
Finally, we can see information about each account’s home directory and shell such as csh, ksh, bash and more:
$ logins -x
$ logins -x -l vivek

Conclusion

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11 Ways to Find User Account Info and Login Details in Linux

This article will show you eleven useful ways to find the information about users on a Linux system. Here we’ll describe commands to get a user’s account details, show login details as well as what users are doing on the system.

If you want to add users in Linux, use the useradd utility, and to modify or change any attributes of a already created user account, use the usermod via the command line as explained in the following guides:

We’ll start by looking at commands to find a user’s account information, then proceed to explain commands to view login details.

1. id Command

id is a simple command line utility for displaying a real and effective user and group IDs as follows.

2. groups Command

groups command is used to show all the groups a user belongs to like this.

3. finger Command

finger command is used to search information about a user on Linux. It doesn’t come per-installed on many Linux systems.

To install it on your system, run this command on the terminal.

It shows a user’s real name; home directory; shell; login: name, time; and so much more as below.

4. getent Command

getent is a command line utility for fetching entries from Name Service Switch (NSS) libraries from a specific system database.

To get a user’s account details, use the passwd database and the username as follows.

5. grep Command

grep command is a powerful pattern searching tool available on most if not all Linus systems. You can use it to find information about a specific user from the system accounts file: /etc/passwd as shown below.

6. lslogins Command

lslogins command shows information about known users in the system, the -u flag only displays user accounts.

7. users Command

users command shows the usernames of all users currently logged on the system like so.

8. who Command

who command is used to display users who are logged on the system, including the terminals they are connecting from.

9. w Command

w command shows all users who are logged on the system and what they are doing.

10. last or lastb commands

last/lastb commands displays a list of last logged in users on the system.

To show all the users who were present at a specified time, use the -p option as follows.

11. lastlog Command

lastlog command is used to find the details of a recent login of all users or of a given user as follows.

That’s it! If you know any other command-line trick or command to view user account details do share with us.

You’ll find these related article so useful:

In this article, we’ve explained various ways to find information about users and login details on a Linux system. You can ask any questions or share your thoughts via the feedback form below.

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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
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:

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UNIX / Linux List Current Logged In Users

H ow do I print the user names of users currently logged in to the current UNIX / Linux host / server from a command prompt?

You need to use any one of the following command line tools to list currently logged in users on Linux or Unix-like systems.

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

Tutorial details
Difficulty level	Easy
Root privileges	Yes
Requirements	w or who command on Linux and Unix
Est. reading time	5m

The following two file keep login records on Linux and Unix-like systems:

• /var/run/utmp – Keeps and allows us to discover information about who is currently using the system. Please note that there may be more L inux and Unix users currently using the system, because not all programs use utmp logging . In other words, poorly written app, hidden programs, malware, and other bad stuff will not be useful to list logged in users.
• /var/log/wtmp – Keeps records all logins and logouts.

We simply cannot read these files using cat command/grep command/egrep command as file is in binary database format. Hence, we use the following commands to find currently logged in users in Linux and Unix-like systems.

Linux Command To List Current Logged In Users

1. w command – Shows information about the users currently on the machine, and their processes.
2. who command – Display information about users who are currently logged in.
3. users command – See the login names of the users currently on the system, in sorted order, space separated, on a single line. It reads all information from /var/run/utmp file.

How to find currently logged in users in Linux

Open a terminal (or login into remote server using ssh command) and type the following commands.

Using w command to list current logged in users under Unix or Linux

Open the terminal application and then type the w command:
$ w

Fig.01: w command in action.

Understanding w command outputs

From Fig.01 we see the following for each user:

• USER – Linux or Unix login name.
• TTY – The tty name.
• FROM The remote host or IP address.
• @Login – Login time.
• IDEL – Idle time.
• JCPU – The JCPU time is the time used by all processes attached to the tty. However, it does not include past background jobs, but does include currently running background jobs.
• PCPU – The PCPU time is the time used by the current process, named in the “what” field.
• WHAT – The command line of that users current process.

To see info about a user named tom, enter:
$ w tom
Tell w command not print header:
$ w -h
$ w —no-header
We can also ignore current process username by passing the -u or —no-current to the w command:
$ w -u
$ w —no-current
Want to see remote hostname field? Try:
$ w -f
Show IP address instead of hostname for from field:
$ w -i
We can also old style output. In other words old outputs prints blank space for idle times less than one minute:
$ w -o

Display all logged in users using who command

The who command works on all Unix like operating systems such as macOS, *BSD, Linux and so on. The syntax is pretty simple:
# who
Here is what we see:

The who command displays the following information:

• root – The username
• pts/0 – Type of the terminal device. In this example, we see pseudoterminal pts/0 used by root user.
• 2013-03-12 15:10 – User login date and time stamp.
• (10.1.3.177) – The remote IP address from which the user logged into this server.

We can pass the -a option to who command as follows to see time of last system boot, display dead processes, system login processes, active processes spawned by init/systemd, print current runlevel, print last system clock change, show user’s message status, and list users logged in to Linux or Unix box:
# who -a
Here is output from older Linux system (pre Systemd):

Sample outputs from Systemd based Linux sysetem:

Getting help with the whois command

You can pass the following options to the who command (taken from the who command man page):

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users command

Open a terminal or login over the ssh session and enter the following users command:
$ users
Output who is currently logged:

Vieing logged in users with last command

Want to see a listing of last logged in users? Use the last command to lookup binary database called /var/log/wtmp and displays a list of all users logged in (and out) since that file was created. For instance see history for user named ‘vivek’:
$ last vivek

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