most_active_users

#!/bin/bash
###########################################################################################################################################################################
# Sample #1
#
# Write a program most_active_users that is called with two command line arguments, an /etc/passwd file and its respective /etc/group file, eg:
#
# most_active_users passwd group
# most_active_users should write to stdout the group with the highest number of users that can currently log in, along with the actual count, delimited by a : character.
#
# For example, given then included files passwd and group, the output should be:
#
# root:3
#
###########################################################################################################################################################################

readonly AVAILABLE_SHELLS="/bin/bash"

function print_usage {
  echo
  echo "Usage: most_active_users [OPTIONS]"
  echo
  echo "This script can be used to get the highest number of users that can currently login."
  echo
  echo "Options:"
  echo
  echo -e "  --group-file\t\tfile path for group file."
  echo -e "  --passwd-file\t\tfile path for passwd file."
  echo
  echo "Example:"
  echo
  echo " ./most_active_users --passwd-file passwd --group-file group"
}

function log {
  local -r level="$1"
  local -r message="$2"
  local -r timestamp=$(date +"%Y-%m-%d %H:%M:%S")
  >&2 echo -e "${timestamp} [${level}] [$SCRIPT_NAME] ${message}"
}

function log_info {
  local -r message="$1"
  log "INFO" "$message"
}

function log_warn {
  local -r message="$1"
  log "WARN" "$message"
}

function log_error {
  local -r message="$1"
  log "ERROR" "$message"
}

function assert_not_empty {
  local -r arg_name="$1"
  local -r arg_value="$2"

  if [[ -z "$arg_value" ]]; then
    log_error "The value for '$arg_name' cannot be empty"
    print_usage
    exit 1
  fi
}

function user_has_shell(){
  local -r user_shell="$1"
  [[ $user_shell == *"${AVAILABLE_SHELLS}"* ]]
}

function get_group_with_most_active_users {
  local top_grp=""
  local let top_count=0
  local passwd_file=""
  local group_file=""

  while [[ $# > 0 ]]; do
    local key="$1"

    case "$key" in
      --passwd-file)
        passwd_file="$2"
        shift
        ;;
      --group-file)
        group_file="$2"
        shift
        ;;
      --help)
        print_usage
        exit
        ;;
      *)
        log_error "Unrecognized argument: $key"
        print_usage
        exit 1
        ;;
    esac

    shift
  done

  assert_not_empty "--passwd-file" "$passwd_file"
  assert_not_empty "--group-file" "$group_file"

  log_info "Starting ..."

  for line in `cat ${group_file}`; do
    local let tmp_count=0 
    local tmp_grp=$(echo $line | awk -F ':' '{print $1}')
    local users=$(echo $line | awk -F ':' '{print $4}')

    for user in `echo ${users} | sed "s/,/ /g"`; do
      local user_shell=$(grep "^${user}" $passwd_file | awk -F ':' '{print $7}')
      if $(user_has_shell $user_shell ); then
        let tmp_count++
      fi
    done

    if (( tmp_count > top_count )); then
      top_count=$tmp_count
      top_grp=$tmp_grp
    fi
  done

  echo "${top_grp}:${top_count}"
  log_info "finishig..."
}

get_group_with_most_active_users "$@"