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Automating useradd Using Shell Script ​

Problem ​

In Linux environments, creating users is a common task. However, doing it manually can be time consuming, especially when handling multiple users at once.

Goal ​

To reduce repetition by automating the useradd process, while still allowing manual override when needed.

Solution – Bash Script for useradd ​

Features: ​

  • Create user with expiration date to meet the best practice
  • Validate user existence before attempt to create user
  • Print success/failure feedback.

Script Example ​

Create a file named useradd.sh and paste the following:

bash
#!/bin/bash
## setup logging
function log() {
  if [[ -n "${LOG:-}" ]]; then
    printf '%s\n' "$*" | tee -a "$LOG" >&2
  else
    printf '%s\n' "$*" >&2
  fi
}
function fatal() { log "ERROR: $*"; exit 1; }

## Function read user input
function read_user_input() {
    default_expiry=$(date -d "+1 month" "+%Y-%m-%d")
    read -r -p "Enter username you'd like to create = " username
    read -r -p "Enter expiration date for user (default: $default_expiry): " input
    exp_date="${input:-$default_expiry}"
}

## Function create user
function create_user() {
    if sudo useradd "${username}" -e "${exp_date}"; then
        log "INFO: User '${username}' created successfully with expiry: ${exp_date}"
    else
        fatal "Failed to create user '${username}'. Check permissions or inputs."
    fi
}

## Function check if user exists
function check_if_user_exist() {
    read_user_input
    while grep -q "${username}" /etc/passwd;
    do
        log "User '${username}' already exist's, please enter other name"
        read_user_input
    done
    create_user && log "INFO: create user '${username}' success"
}

## Main program
check_if_user_exist

Usage ​

  1. Make the script executable:
bash
chmod +x useradd.sh
  1. Run the script:
bash
bash useradd.sh

Notes & Improvements ​

This script is part of an ongoing learning project and may not fully reflect best practices. Future improvements include:

  • Adding support for multi-user creation
  • Secure credential handling via stdin or environment variables.

I'm actively improving this script toward production-ready standards.