Check if subordinate user and group ids exist and suggest how to create them

check-subuid.sh

#!/bin/sh

RED='\033[0;31m'
NOCOLOR='\033[0m' # No Color
GREEN='\033[0;32m'

RANGE_SIZE=65536

USERID="$1"

if [ "${USERID}" = "" ]; then
  echo "ERROR: You must specify a user name as first argument"
  exit 1
fi

if getent passwd "${USERID}" ; then
  echo -e "${GREEN}INFO: User ${USERID} is valid${NOCOLOR}"
else
  echo -e "${RED}ERROR: Invalid user name ${USERID}${NOCOLOR}"
  exit 1
fi

echo "INFO: Checking subordinate user ids for user: $USERID"
SUBUID_FOUND=0
if grep "${USERID}:" /etc/subuid ; then
 echo "INFO: Subordinate user ids found for $USERID."
 SUBUID_FOUND=1
else
 echo "INFO: Subordinate user ids NOT found for $USERID."
fi

echo "INFO: Checking subordinate group ids for user: $USERID"

SUBGID_FOUND=0
if grep "${USERID}:" /etc/subgid ; then
 echo "INFO: Subordinate group ids found for $USERID."
 SUBGID_FOUND=1
else
 echo "INFO: Subordinate group ids NOT found for $USERID."
fi


if [ "${SUBUID_FOUND}" = "1" -a "${SUBGID_FOUND}" = "1" ]; then
  echo -e "${GREEN}INFO: Both user and group subordinate ids were found. All is good. Exiting${NOCOLOR}"
  exit 0
fi

if [ "${SUBUID_FOUND}" = "0" ]; then
  echo "INFO: Subordinate USER ids not found for $USERID. Creating them..."

  LAST_SUBUID=$(cut -d: -f2 /etc/subuid | sort -n | tail -1)
  if [[ -z $LAST_SUBUID ]]; then
    NEXT_SUBUID=1000000
  else
    NEXT_SUBUID=$(( $LAST_SUBUID + $RANGE_SIZE ))
  fi

  SUBUID_START="${NEXT_SUBUID}"
  SUBUID_LAST=$(( $SUBUID_START + $RANGE_SIZE - 1 ))

  echo "INFO: Please add subordinate USER id range to user running the command:"
  echo -e "${RED}sudo usermod --add-subuids ${SUBUID_START}-${SUBUID_LAST} ${USERID}${NOCOLOR}"
fi

if [ "${SUBGID_FOUND}" = "0" ]; then
  echo "INFO: Subordinate GROUP ids not found for $USERID. Creating them..."

  LAST_SUBGID=$(cut -d: -f2 /etc/subgid | sort -n | tail -1)
  if [[ -z $LAST_SUBGID ]]; then
    NEXT_SUBGID=1000000
  else
    NEXT_SUBGID=$(( $LAST_SUBGID + $RANGE_SIZE ))
  fi

  SUBGID_START="${NEXT_SUBGID}"
  SUBGID_LAST=$(( $SUBGID_START + $RANGE_SIZE - 1 ))

  echo "INFO: Adding subordinate GROUP id range to user running the command:"
  echo -e "${RED}sudo usermod --add-subgids ${SUBGID_START}-${SUBGID_LAST} ${USERID}${NOCOLOR}"
fi