Creating Users

System User

System users are typically for services that don't require login access.

adduser --system --group --home /opt/name name

Normal User with Locked Password

Creates a user with a specific UID/GID, useful for consistent deployments across systems.

useradd -u 2000 -g 2000 -d "/opt/deploy" -m -s /usr/sbin/nologin deploy

User Creation Script with Parameters

This script accepts input parameters for flexibility across different deployments:

#!/bin/bash
set -euo pipefail

# Script: create_user.sh
# Usage: ./create_user.sh <username> <uid> <gid> <home_dir> <shell> [gecos]
# Example: ./create_user.sh cortex 2001 2001 /opt/cortex /bin/bash "Cortex Bot"

validate_input() {
    if [[ $# -lt 5 ]]; then
        echo "Usage: $0 <username> <uid> <gid> <home_dir> <shell> [gecos]"
        echo "Example: $0 cortex 2001 2001 /opt/cortex /bin/bash 'Cortex Bot'"
        exit 1
    fi
    
    # Validate UID is numeric and doesn't exist
    if ! [[ $2 =~ ^[0-9]+$ ]]; then
        echo "Error: UID must be numeric"
        exit 1
    fi
    
    if id -u "$2" >/dev/null 2>&1; then
        echo "Error: UID $2 already exists"
        exit 1
    fi
    
    # Validate GID is numeric
    if ! [[ $3 =~ ^[0-9]+$ ]]; then
        echo "Error: GID must be numeric"
        exit 1
    fi
}

create_user() {
    local username=$1
    local uid=$2
    local gid=$3
    local home_dir=$4
    local shell=$5
    local gecos="${6:-System Account}"
    
    echo "Creating group: $username (GID: $gid)"
    groupadd -g "$gid" "$username" 2>/dev/null || echo "Group already exists"
    
    echo "Creating user: $username (UID: $uid)"
    useradd \
        -u "$uid" \
        -g "$username" \
        -d "$home_dir" \
        -m \
        -s "$shell" \
        -c "$gecos" \
        "$username"
    
    echo "Locking password for $username"
    passwd -l "$username" &> /dev/null
    
    echo "✔ User $username created successfully"
    echo "  UID: $uid, GID: $gid"
    echo "  Home: $home_dir"
    echo "  Shell: $shell"
}

validate_input "$@"
create_user "$@"

Usage:

chmod +x create_user.sh
./create_user.sh cortex 2001 2001 /opt/cortex /bin/bash "Cortex Bot"
./create_user.sh coco-deploy 2002 2002 /opt/coco-deploy /bin/bash "Coco Deploy Bot"