Create an account for each user and add the user to its group from a text file

Question

I have a username.txt file which contains their username and specific group. As of right now I'm trying to create a bash script which allows me to create an account for each user and add the user to its group in one command.

This is currently my failed bash script:

#!/bin/bash

sudo addgroup staff
sudo addgroup visitors

username="username.txt"

while read line; do
sudo useradd $-Eo '^[^,]+' $username;
if [grep staff $username]; then
  sudo usermod -a -G staff
else
  sudo usermod -a -G visitors
done < $username

This is what is inside my username.txt file:

ellipsiscoterie,visitor
magnetcommonest,visitor
belateddefensive,staff
bobstercaramelize,staff

Answer 1

Please try this as a solution. You are using a comma-separated file so my assumption is that you want to use more than two groups at one point. What you are doing is not completely wrong, but I would avoid using if else in this case as it will need a rewrite in case more groups will be needed. The creation of the group is handled within the loop as well.

#!/bin/bash
while read config
do
        USERTOCREATE=$(awk -F, '{print $1}' <(echo "$config"))
        GROUPTOASSIGN=$(awk -F, '{print $2}' <(echo "$config"))
        if [[ ! $(groups) =~ $GROUPTOCREATE ]]; then addgroup $GROUPTOASSIGN; fi
        useradd $USERTOCREATE
        usermod -a -G $GROUPTOASSIGN
done < users

This code is a simple while loop that uses two variables USERTOCREATE and GROUPTOASSIGN which are assigned using the awk. -F, flag in awk is to set a field separator FS variable to comma. This way awk can split input into variables $1 and $2. I'm not sure if you are familiar with <() this is a file descriptor that allows us to treat the output of echo "$config" as a file. $config is nothing else than the line coming from the file the script is reading.

Answer 2

#!/bin/bash
i=0

n=$(wc -l <username.txt)
while [ $i -le $n ]
do
        L=$(awk "NR==$i" username.txt)
        if [ -n "$L" ]; then
                user=$(echo "$L" | cut -d',' -f1)
                group=$(echo "$L" | cut -d',' -f2)
                useradd $user
                groupadd $group
                usermod -a -G $group $user
        fi

i=$((i+1))
done

Answer 3

You could parse the username.txt line-wise, with , as field separator:

#!/bin/bash
sudo addgroup staff
sudo addgroup visitors

while IFS=, read -r username maingroup
do
   sudo adduser --ingroup "$maingroup" "$username"
done < username.txt

This would read the comma-separated tokens into the shell variables $username and $maingroup, respectively, and execute the adduser command to create the user $username with primary group $maingroup.