Generate user account

add_user_accounts.sh

#!/usr/bin/env bash

#####
# Set default command line options
#####
USERNAME_PREFIX=user
USERNAME_SUFFIX_START=1
USERNAME_SUFFIX_END=100
USERNAME_SUFFIX_ZERO_PADDING_LENGTH=4

usage="USAGE: $(basename $0) [-h] [-u <user_prefix>] [-s <start>] [-e <end>] [-z <zero_padding>]

User creation.
  where:
    -h Show this help text
    -u Username prefix (default: ${USERNAME_PREFIX})
    -s Username suffix start number (default: ${USERNAME_SUFFIX_START})
    -e Username suffix end number (default: ${USERNAME_SUFFIX_END})
    -z Zero-pad username suffix number to this length (default:${USERNAME_SUFFIX_ZERO_PADDING_LENGTH})"

PWGEN_ARGS=()

#####
# Parse command line options
#####
while getopts ":hu:s:e:z:" opt; do
  case $opt in
    h) >&2 echo "${usage}"
       exit
       ;;
    u) USERNAME_PREFIX=${OPTARG}
       ;;
    s) USERNAME_SUFFIX_START=${OPTARG}
       ;;
    e) USERNAME_SUFFIX_END=${OPTARG}
       ;;
    z) USERNAME_SUFFIX_ZERO_PADDING_LENGTH=${OPTARG}
       ;;
    ?) >&2 printf "Illegal option: '-%s'\n" "${OPTARG}"
       >&2 echo "{$usage}"
       exit 1
       ;;
    :) >&2 echo "Option -${OPTARG} requires an argument."
      >&2 echo "${usage}"
      exit 1
      ;;
    *) >&2 echo "${usage}"
       exit
       ;;
  esac
done

for i in $(seq --format "%0${USERNAME_SUFFIX_ZERO_PADDING_LENGTH}g" ${USERNAME_SUFFIX_START} ${USERNAME_SUFFIX_END}); do
  useradd --home-dir /home/${USERNAME_PREFIX}${i} --shell /bin/bash ${USERNAME_PREFIX}${i}
done