How to write a small bash script to create users?

Question

bash

You need to write a script that will create a new user user_[N+1]

#!/bin/bash

N = $(($N+1))
sudo useradd user_$N -p pass_$N
echo "User added!"

I will be glad for any help!

Answer 1

it feels like the condition is incomplete, so I’ll complicate it a little, and if you wish, you can easily simplify the script to the desired result
. Suppose you need to create N users (from 1 to N) and set a password for them, and all this with the corresponding numerical prefix . That is, write a script that receives a base name and password as input, as well as the number of users that need to be created.
let's say the script name is luser.sh

#!/usr/bin/env bash

USER=$1 # базовая часть имени пользователя
PASS=$2 # базовая часть пароля
N=$3    # количество пользователей
for (( i = 1; i <= $N; i++ )); do
  useradd "${USER}_$i" && $(echo "${USER}_$i:${PASS}_$i" |chpasswd)
  echo "User ${USER}_$i added!"
done

script example:

$ sudo ./luser.sh user pass 3
User user_1 added!
User user_2 added!
User user_3 added!

check that users with a base in the name user have actually been created:

$ grep -e "^user" /etc/passwd
user_1:x:1314:1314::/home/user_1:/bin/bash
user_2:x:1315:1315::/home/user_2:/bin/bash
user_3:x:1316:1316::/home/user_3:/bin/bash

Answer 2

#!/bin/bash
for ((i=1; i < 10; i++))
do
echo $i
done

Answer 3

I would like more details, because it is not entirely clear how the script will be used and, accordingly, what exactly it should do.
I will assume that when the script is called, one new user with a template name should be created.
Those. you need to somehow get a list of such users from the system, find the last one, take a number from it and increase it by one.
If you definitely need a monotonically increasing number, then something like this:

lastUserSuffix=$(cat /etc/passwd | awk 'BEGIN {FS=":"}; {print $1}' | grep systemd | sort -n | sed 's/systemd-//' | tail -1)

I'm looking for users named systemd-*** here, I think it will not be difficult for you to modify the example for your own purposes.

Answer 4

It is better not to use useradd, it gives too extended rights to the home directory (access not only to the user, but to his entire group). Use adduser.