Automating User and Group Management on Linux with a Shell Script

#!/bin/bash

# Check if the correct number of arguments is passed
if [ “$#” -lt 1 ]; then
echo “Usage: $0 <filename>”
exit 1
fi

# The second argument is the filename
filename=“$1“

# Check if the file exists
if [ ! -f “$filename“ ]; then
echo “File not found: $filename“
exit 1
fi

# Function to trim leading and trailing whitespace
trim() {
local var=“$*“
# Remove leading whitespace
var=“${var#“${var%%[![:space:]]*}“}“
# Remove trailing whitespace
var=“${var%“${var##*[![:space:]]}“}“
echo -n “$var“
}

# Define the file to check
user_mgt_file_path=“/var/log/user_management.log”
user_mgt_dir_path=$(dirname “$user_mgt_file_path“)

# Check if the directory exists
if [ ! -d “$user_mgt_dir_path“ ]; then
# Create the directory if it doesn’t exist
mkdir -p “$user_mgt_dir_path“
fi

# Check if the file exists
if [ ! -f “$user_mgt_file_path“ ]; then
# Create the file if it doesn’t exist
touch “$user_mgt_file_path“
echo “File ‘$user_mgt_file_path‘ created.”
fi

# Define the file to check
user_pass_file_path=“/var/secure/user_passwords.csv”
user_pass_dir_path=$(dirname “$user_pass_file_path“)

# Check if the directory exists
if [ ! -d “$user_pass_dir_path“ ]; then
# Create the directory if it doesn’t exist
mkdir -p “$user_pass_dir_path“
echo “Directory $user_pass_dir_path created…” >> $user_mgt_file_path
fi

# Check if the file exists
if [ ! -f “$user_pass_file_path“ ]; then
# Create the file if it doesn’t exist
touch “$user_pass_file_path“
echo “File $user_pass_file_path created…” >> $user_mgt_file_path
fi

# Loop through each line in the file
while IFS= read -r line; do
# Process each line
# echo “Processing: $line”

# Define the username and password
# Trim leading and trailing whitespace
username=$(trim “${line%%;*}“)
password=$(LC_CTYPE=C < /dev/urandom tr -dc ‘A-Za-z0-9!@#$%&*’ | head -c 16)

# Generate a random password
echo “Password generated for user $username“ >> $user_mgt_file_path

usergroups=$(trim “${line#*;}“)

# Split the usergroups into an array
IFS=‘,’ read -r -a groups_array <<< “$usergroups“
for i in “${!groups_array[@]}“; do
groups_array[$i]=$(trim “${groups_array[$i]}“)
# groups_array[$i]=$(echo “${groups_array[$i]}” | xargs)
done

# Extract the primary group (first element)
primary_group=“${groups_array[0]}“

# Extract the remaining groups
if [ “${#groups_array[@]}“ -gt 1 ]; then
additional_groups=$(IFS=,; echo “${groups_array[*]:1}“)
else
additional_groups=“”
fi

# Function to check if a group exists, and create it if it doesn’t
create_group_if_not_exists() {
groupname=“$1“
if ! getent group “$groupname“ > /dev/null 2>&1; then
groupadd “$groupname“
echo “User group ‘$groupname‘ created…” >> $user_mgt_file_path
else
echo “User group ‘$groupname‘ already exist! Skipping” >> $user_mgt_file_path
fi
}

# Check and create primary group
create_group_if_not_exists “$primary_group“

# Check and create additional groups
for group in “${groups_array[@]}“; do
create_group_if_not_exists “$group“
done

# Check if the group already exists
if ! getent group “$username“ > /dev/null 2>&1; then
# Create the group if it doesn’t exist
groupadd “$username“
echo “Directory $user_pass_dir_path created…” >> $user_mgt_file_path # TODO
fi

# Check if the user already exists
if id “$username“ &>/dev/null; then
echo “User ‘$username‘ already exists. Skipping…”
echo “User ‘$username‘ already exists. Skipping…” >> $user_mgt_file_path
else
# Create the user with the primary group and additional groups if any
if [ -n “$additional_groups“ ]; then
useradd -m -g “$primary_group“ -G “$additional_groups“ -s /bin/bash “$username“
else
useradd -m -g “$primary_group“ -s /bin/bash “$username“
fi

# Create the user with the specified group and set the password
# useradd -m -g “$username” -s /bin/bash “$username”
echo “$username:$password“ | chpasswd
echo “User ‘$username‘ created! Password has also been set for the user” >> $user_mgt_file_path

# Display the created username and password
echo “Password for user ‘$username‘ is: $password“ >> $user_pass_file_path

# Set the home directory path
home_directory=“/home/$username“

# Set permissions and ownership for the home directory
chown “$username:$primary_group“ “$home_directory“
chmod 755 “$home_directory“

# Ensure appropriate permissions for additional groups
for group in “${groups_array[@]}“; do
if [ “$group“ != “$primary_group“ ]; then
chmod g+rx “$home_directory“
setfacl -m “g:$group:rx” “$home_directory“
fi
done

echo “User $username created with home directory $home_directory“ >> $user_mgt_file_path
echo “Users created!”
fi
done < “$filename“

chmod +x user_mgmt.sh

./user_mgmt.sh users.txt

bash user_mgmt.sh users.txt