Write script to create multiple users with pre-defined passwords - linux

Question

So I would like to make a script that create users from users.txt running
useradd -m -s /bin/false users_in_the_users.txt
and fill the password from passwords.txt twice (to confirm the passwords)
This is the script
#!/bin/bash
# Assign file descriptors to users and passwords files
exec 3< users.txt
exec 4< passwords.txt
exec 5< passwords.txt
# Read user and password
while read iuser <&3 && read ipasswd <&4 ; do
# Just print this for debugging
printf "\tCreating user: %s with password: %s\n" $iuser $ipasswd
# Create the user with adduser (you can add whichever option you like)
useradd -m -s /bin/false $iuser
# Assign the password to the user, passwd must read it from stdin
passwd $iuser
done
The problem is, it does not fill the passwords. And 1 more thing, I want the script to fill the passwords twice.
Any suggestions?

Answer 1

You have to supply the password on stdin. Replace:
passwd $iuser
with:
passwd "$iuser" <<<"$ipasswd
$ipasswd"
or, as suggested by mklement0:
passwd "$iuser" <<<"$ipasswd"$'\n'"$ipasswd"
The incantation <<< creates a here-string. The string that follows the <<< is provided as standard in to the command which precedes the <<<. In this case we provide the two copies of the password that the passwd command wants.
(The script reads these passwords from a plain text file. I will assume that your situation is some special case for which this is not as dangerous as it normally would be.)

Answer 2

John1024's answer is the correct one - his warning about reading passwords from plain-text files bears repeating.
Let me show the solution in context, without the file-descriptor acrobatics (exec 3<, ...):
#!/bin/bash
# NOTE: Be sure to run this script with `sudo`.
# Read user and password
while read iuser ipasswd; do
# Just print this for debugging.
printf "\tCreating user: %s with password: %s\n" $iuser $ipasswd
# Create the user with adduser (you can add whichever option you like).
useradd -m -s /bin/false $iuser
# Assign the password to the user.
# Password is passed via stdin, *twice* (for confirmation).
passwd $iuser <<< "$ipasswd"$'\n'"$ipasswd"
done < <(paste users.txt passwords.txt)
paste users.txt passwords.txt reads corresponding lines from the two files and puts them on a single line, separated with \t.
The result is piped to stdin via a process substitution (<(...)).
This allows read to read from a single source.
$\n is an ANSI C-quoted string that produces a (literal) newline.

Answer 3

#! /bin/bash
for i in {1..100}
do
`sudo mkdir -p /root/Desktop/userm$i`
`sudo useradd -m -d /root/Desktop/userm$i -s /bin/bash userm$i`
echo "userm$i:userm$i" | chpasswd
done
this will create 100 users. user name will be (userm1-userm100). home directory will be /root/Desktop/(userm1-user100)
password will be (userm1-userm100)

Answer 4

Instead of using this line:
useradd -m -s /bin/false $iuser
Try this one:
useradd -m -s /bin/false -p $ipasswd $iuser
You don't actually need this:
passwd $iuser <<< "$ipasswd"$'\n'"$ipasswd"

Answer 5

Kindly run the below script.
#!/bin/bash
#purpose: bash script to create multiple users with pre-defined passwords at once.
#Read_Me: The import file should be in two columns, first users name and second passwords.
#author: Bablish Jaiswal
#contact: linux.cnf#gmail.com
read -p "Kindly import/type Users Name-password file with location:- " creation_info
cat $creation_info |while read i p
do
( useradd $i && echo -e "${p}\n${p}" | passwd $i ) > /dev/null 2>&1 && echo $user ${i} created and password is ${p} || echo ${i} failed
done