Are you wondering how to add a user with a password using a shell script under Linux? Let us see how to add a new user and set/change a password including chaning the existing Linux user’s password in a Linux shell script.
You can quickly write a shell script that reads username, password from the keyboard, and add a username to the /etc/passwd and store encrypted password in /etc/shadow file using useradd command. The useradd command/adduser command used to create a new user on Linux and passwd command to set or change password for users. This page shows how to add a user account AND password with a bash shell script running on Linux operating systems.
Linux shell script to add a user with a password
The syntax is as follows:
useradd -m -p EncryptedPasswordHere username
Where,
- -m : The user’s home directory will be created if it does not exist.
- -p EncryptedPasswordHere : The encrypted password, as returned by crypt().
- username : Add this user to the Linux system,
Step 1 – Create an encrypted password
You need to create an encrypted password using Perl crypt() as follows:
crypt($plain, $salt) ## perl one liner ## perl -e 'print crypt("Your-Clear-Text-Password-Here", "salt"),"\n"' |
Please note that crypt() is a one-way hash function. The PLAINTEXT ($plain) and SALT are turned into a short string, called a digest, which is returned. The same PLAINTEXT and SALT will always return the same string, but there is no (known) way to get the original PLAINTEXT from the hash. Small changes in the PLAINTEXT or SALT will result in large changes in the digest. Let us try out perl example:
perl -e 'print crypt("2IL@ove19Pizza4_", "salt"),"\n"'
Sample outputs:
sa.KT9zrGYeg2
The Perl command will display the encrypted password (sa.KT9zrGYeg2) on screen. The Perl crypt() function is a one way encryption method meaning, once a password has been encrypted, it cannot be decrypted. The password string is taken from the user and encrypted with the salt and displayed back on computer screen. We can store an encrypted password using the following syntax:
password="1YelloDog@" pass=$(perl -e 'print crypt($ARGV[0], "password")' $password) echo "$pass" |
Sample outputs”
paU5t8Al/qf6M
Warning: You must understand other users and system processes can view passwords processed using the CLI tools, and it is a security risk when you store passwords in a plain text format. Linux can hide processes from other users and ps command using this guide to limit some damage. I would recommend using Ansible Vault to storing passwords as well as changing them in bulk.
Step 2 – Shell script to add a user and password on Linux
Based upon above discussion here is a sample shell script (Download link):
#!/bin/bash # Purpose - Script to add a user to Linux system including passsword # Author - Vivek Gite <www.cyberciti.biz> under GPL v2.0+ # ------------------------------------------------------------------ # Am i Root user? if [ $(id -u) -eq 0 ]; then read -p "Enter username : " username read -s -p "Enter password : " password egrep "^$username" /etc/passwd >/dev/null if [ $? -eq 0 ]; then echo "$username exists!" exit 1 else pass=$(perl -e 'print crypt($ARGV[0], "password")' $password) useradd -m -p "$pass" "$username" [ $? -eq 0 ] && echo "User has been added to system!" || echo "Failed to add a user!" fi else echo "Only root may add a user to the system." exit 2 fi |
Close and save the script file. Next set permissions using the chmod command:
chmod +x add-user-script.sh
Run it as following
$ ./add-user-script.sh
Only root may add a user to the system.
$ sudo ./add-user-script.sh
Or run it as root user:
# ./adduser
Sample outputs:
Enter username : roja Enter password : HIDDEN User has been added to system!
Now user roja can login with a password called HIDDEN. Here is sample session outputs:
Step 3 – Change existing Linux user’s password in one CLI
We are going use the chpasswd command that reads a list of user names and password pairs from the keyboard and uses this information to update a group of existing users. The syntax is as follows:
echo "user_name:password" | chpasswd
However, the passwords must be provided in clear-text format, and are encrypted by the chpasswd command. For example, set or change user password, run:
# echo 'vivek:@iLovePizzaEvery1day' | chpasswd
Verify that password has been changed using the chage command:
# chage -l vivek
We can use the grep command/egrep command to search for usernames:
grep "^username" /etc/passwd
grep "^tom" /etc/passwd
If the chpasswd command not installed, use your systems package manager tool such as apt command/apt-get command/dnf command/yum command to install the same.
Step 4 – Create Users and change passwords with passwd on a CentOS/RHEL
The passwd command on CentOS/RHEL/Fedora and co comes with a special command-line option to change the password using a shell pipe as follows:
# echo "YourPassword" | passwd --stdin UserName
# echo "I4Love2Ubu@ntuLinux_" | passwd --stdin vivek
Outputs from sample session:
Changing password for user vivek. passwd: all authentication tokens updated successfully.
So the --stdin option is used to indicate that passwd command should read the new password from standard input such as keyboard, which can be a pipe and must be run by root user.
Conclusion
You learned various methods to add a new user and set a password using a shell script. See the following for more info:
40 Linux Server Hardening Security Tips [2019 edition]
30 Best Sources For Linux / *BSD / Unix Documentation On the Web
Linux 25 PHP Security Best Practices For Sys Admins
30 Linux System Monitoring Tools Every SysAdmin Should Know
Linux / UNIX: Find Out If File Exists With Conditional Expressions in a Bash Shell
The Novice Guide To Buying A Linux Laptop
Top 25 Nginx Web Server Best Security Practices
I just want to send one script which I have made for changing password of any user from remote machine.
Here I have created one file called “host” which contents host ips.
Shell script code
#!/bin/bash read -p "Enter Username: " username read -ers -p "Enter New password for user $username: " paswd echo read -ers -p "Enter Root Password: " rpaswd echo password=`python file ${paswd}`; echo "$username $password $npaswd" cat host | while read line do #####expect#### status=$(expect -c " spawn ssh $line usermod -p $password $username expect { password: { send "$rpaswdn"; exp_continue } } exit ") echo "" echo "$status" > log.txt #####end of expect####### donepython code – file [for crypt()]
Hope this will help somebody. 🙂
Cheers!
Amol,
Nice script.
Appreciate your post.
Hey forgot one thing….there is one more file called “file”, and contents of these files are –
import crypt; import sys; print crypt.crypt(sys.argv[1],”salt”);
Yes, i thought so… there is line about python… thanks
I always wondered if there was a bash /CLI command to list the users, is there?
I see here
egrep “^$username†/etc/passwd >/dev/null
so there is not?
egrep -v ^xyz /etc/passwd | cut -d”:” -f1
Add this line in a script which displays all the users in your machine
i have used ^xyz , Starting with that. genarally user names will never start with that , so we get the desired result as output becouse of the option -v .
OR
As a root
vim usershow
1 #!/bin/bash
2 #this script displays the users in machine.
3 egrep -v ^xyz /etc/passwd | cut -d”:” -f1 |less
esc:wq
cp usershow /usr/local/sbin/
chmod -R +x /usr/local/sbin
Thats it…Enjoymaadi
usershow
Remove ‘>/dev/null‘ and you should see username if exists in /etc/passwd. To display list just type:
cut -d: -f1 /etc/passwdits great but it is more powerful if you include the functionality to add lage number of users at once
like in my uni more then 15000 stuent it is almoste inpossible to create their acccounts one by one
master,
You may take help of this my previous post – How to create multiple users accounts in batch / bulk
HTH
How I need edit the script to add the user in particular group and disable them by accessing telnet.
example:
useradd -d /home/example1 -s /bin/false -g popusers example1
># Allotment Says:
>March 23rd, 2007 (4 weeks ago) at 1:00 pm
>I always wondered if there was a bash /CLI command >to list the users, is there?
>I see here
>egrep “^$username†/etc/passwd >/dev/null
>so there is not?
You can use gawk to list users
gawk -F: ‘{ if ( $3>500 ) print $1 }’/etc/passwd
Could you kindly help me to integrate in this first script to add a user in /etc/shadow from a comma separeted file?
I would like to export a list from a company application, create a .csv , and lunch it from a shell script or a php page in a website to import users in 1 step.
The important is that the password used to access sistem by users is the one I can read in clear characters in the csv file.
Let me know please, and put my address in copy fabio@conecta.it
egrep “^$username†/etc/passwd
don’t u people think that this will not match string
perfectly means if there is user like bhushan and i want to create user bhush…then it will give msg that user already exists…
Sure you can use word based matching:
(echo "username:password")|chpasswdhi vivek,
how to add user without using useradd command?
With all information such as uid(by incrementing existing highest one), gid,…….etc.
I need a shell script that will create a password for users already on the system. How can I do that?
Another way to get encrypted password is command:
openssl passwd yourpass
PASSWORD checking is limited to 8 characters long.
I tried the Script above (adduser.sh), and the password checking is some how up-to 8 characters only. Meaning as long as you have the first 8 characters correct you can login to the system (I tested using su command)
The part I changed on the script is to set username and password as a variable:
username=test
password=secr3t12345
ex.
password=secr3t12345
it will allow secr3t12333333333 or secr3t12
I found the same thing. 8 characters and it ignores the rest.
How do you make it store more than 8 characters?
How can you also get this script to add a samba password at the same time it creates a unix password?
Useful article, I was was looking to add users with a one liner so this helped .. since Debian lacks the crypt command, I didn’t even think to use perl ..
Since I maintain the web server we use, exclusively .. I know all of my accounts have home directories, so I simply do my test to see if a user exists in perl .. but the same could be done in a shell script
if (-e “/home/$username”) {
print “The account already exists bonehead!”;
exit;
} else {
// get on with it
}
hi,
i compile this program but when i move to the second part I cant execute it in root . I got a error???
No such file or directory
why is that ???
pls reply me….
how about this one liner script
# useradd -m -p `perl -e ‘print crypt(“your_password”, “salt”),”n”‘` your_username
hi
how to create new user to assign perssion to particular shell and set userid and groupid make this one line command
HI
I like to add bulk of user using bash scripting taking the user name from a text file from a given location and also want to set a sample passwd for the all user who have been created. and also the script has to mail to the corresponding user regarding the username and passwd . Can anyone help me out
Thanks in advance
Sample shell script to add a user
How do I change this to add the users full name ans login shell
Hi Vivek(nixcraft)
Your mentioned shell script giving me an error message while executing it
“line 19: syntex error: unexpected end of the file”
Please check and where it is get stuck..
Thanks
Charanjit Singh
Hi all,
Can someone let me know, How to write script for password expiry notification in solaries.
Hello Everyone,
My self Ravi and I am trying to make one PHP page, from which i can able to create
new user in linux. where in php code will show three boxes
1.) New User Name:
2.) Password:
3.) Botton: Add now
with this php code i want to add new user in linux through web interface.
Kindly please help me out to do that so.
Regadrs,
Ravi
i need to help me. i want to good 100% user email, password and forget password.
frisrt sign user email then get get password number in then open in base.
if forget password then send email get password
Can anyone help me thank harold
simple: echo PASSWORD | passwd USER –stdin
It was very useful your sample,
thanks
Servando
Hey I need a scrip to add 100 users to UNIX server using an Input file which has two input one full name the other username . But i need to generate password in the script which gets incremented with each added user ….
Thanks a lot in advance ….
soumya
Very good script.
hi guys
can any one tell me how to write a script such that the script reads the password and enters to tat user
i just want to know the script
Write a shell script that can be used to:
Detailed requirements
1. The script can only be executed by the root user, administrator or users with administrative rights.
2. If the root user starts the program as specified, it should read the input file and check the new users’ information one by one. If a new user’s information is valid, it should create the account for the user and write the account information to a report file. The report file should have the following format:
account_name;user_id;group_name;group_id;created_date;user_fullname
3. If a new user’s information is not valid, it should not create the account for the user. The error should be written to an error report file. You need to specify the file format.
4. If the root user executes the script incorrectly, e.g., without the necessary parameters or with incorrect parameters, it should provide an appropriate help message to the user. For example, it could show the correct usage of the command.
5. If the root user executes the command with the –h switch, the program should give detailed information about the program and the file structure of the input file.
6. The input file should have the following structure:
• Each line is a user record.
• Each record has four fields separated by commas (,) as follows:
Username,password,groupname,fullname
Note: The password field must be between 9 and 12 characters long. The field for the user’s full name may contain blank spaces. You must specify the features of the other fields. If a group does not exist, the program should create a default group automatically.
pass=$(perl -e ‘print crypt($ARGV[0], “password”)’ $password)
in this block what does $ARGV[0] stores and how it will work
we really appreciate your useful code
The student should write a bash program named myuseradd that accepts a list of users as argument
Script syntax: myuseradd [ [ ..]]
At least one argument must be provided and must not exceed 10 alphanumeric characters.
The script must not use the usedadd or similar commands. It must:
1- Check if user is root. If not the script cannot be run and it exits.
2- Check the number of arguments. If none the script exits.
3- Check if is already used, if yes the script exits.
4- Ask the user to provide the following data:
a. Home directory:
Default is /home/
The script accepts either /home/ or /. must
not exceed 10 alphanumeric characters and the entered home directory
must not exist already.
b. Login shell
Default is /bin/bash
The script can accept one of the shells as listed in /etc/shells.
If provided data does not meet conditions, the user is asked to enter the data again
5- Add user with name , provided home directory and login shell to the system’s users (/etc/passwd file).
6- Assign userid (must be the first available userid greater or equal to 500).
7- Create a new group with group name and gid same as uid and assign it as primary group. This must be done by adding an entry to /etc/group.If the group already exists, no change is done.
8- Create home directory and set required permissions.
9- Copy startup scripts to the home directory (from /etc/skel).
10- Create a line in /etc/shadow that corresponds to the user with a blank password.
11- Call the passwd program to set the password.
12- Produce an output the summarize what it did.
Very appreciated!
I am working a project started from another team in another continent. The document/help we get is zero. So we are on our own.
During the boot, I am stopped by login/password. There are several ways to crack in.
By using your script, I easily add a user(ie, myself) into the system. It works painlessly. Thank you so much!
to change the password ->
echo “User_name:PASSWORD” | chpasswd
I found an very easy way to do this:
For System-Password:
# echo -e “n”|passwd
For SAMBA-Password:
# echo -e “n”|smbpasswd -sa
In some configuration the System-Password will changed with smbpasswd also!
Check /etc/samba/smb.conf for Password-Chat
hello i m new in unix can anyone tell me how to write a bash script which prompts user and assigns a password?
The sample scripts are great.
This script really help me in creating mass user accounts for students.
Thanks
sn
Quality contribution appreciate it
I am using this script but when i run these script it ask me username and when i entered Password i am getting error Failed and when i am not entering password it succesfully create user. Please let me know what i missing..
Thanks
I’m learning UNIX. I would like a script to add a user account (id and password) to multiple UNIX servers. I currently use smit user when a new employee begins working which takes forever because we have over 100 UNIX servers. Please help.
is there a way to do this so you dont have to be the root? im having problems with permissions as i am using a virtual machine so please reply as advice would be greatly appreciated.
hello Admin ,
script having problen in creating user i.e mohit2 if a user mohit23 is present .
it is not exactly grepping the user name from /etc.passwd.
I hope the newly given code will fix your issue, enjoy.
can any one please help on this ..
i need to check around 1000 user’s for all details its mentioned in /etc/passwd.
i need a program on shell script whether the username entered is correct to the password
Vivek Gite,
Thanks very much for this posting, I have referenced this for my computing task!
Would it be possible if you could explain this line by line so I understand how it works? The other thing was, is it possible to also add these users to groups by using the script too?
Thanks once again!
How would I add a user and then add them to a group if the user was inputted in a shell script?
what does the -p and -s -p do?
i DO APPRECIATE THE BLOG THANKS
Hi,
We can use below command for user creation and its password entry.
useradd mayur && echo -e “mayur@123nmayur@123” | passwd mayur
Here,
n is for new line
Hi Admin,
i need a shellscript to add a new user to server
+to access to ssh through i need to copy my public key in the currently created user path
+i want to prevent root permission to new user
+this steps need to be done in centos
can you show how to do this?
Write a script called simple-useradd.sh that adds a local user to the system. This script should:
Take only one argument, or else exit after printing a usage message.
. Check /etc/passwd and decide on the first free user ID. Print a message containing this ID.
Create a private group for this user, checking the /etc/group file. Print a message containing the group ID.
Gather information from the operator user: a comment describing this user, choice from a list of shells (test for acceptability, else exit printing a message), expiration date for this account, extra groups of which the new user should be a member.
. With the obtained information, add a line to /etc/passwd, /etc/group and /etc/shadow; create the user’s home directory (with correct permissions!); add the user to the desired secondary groups.
Set the password for this user to a default known string.