#!/bin/bash
# create_user.sh
# Meryll Larkin  December 1, 2018
# updated October 1, 2019  # defined undefined group, -z on ifs, added : on egrep
# Create login, add to primary, secondary group accounts
# September 9, 2019 added error checking and password reminder
# June 20, 2022 Various updates including UID selection

MYSHELL="/bin/bash"
HOMEBASE="/home"

if [[ $EUID -ne 0 ]]; then
   echo "This script must be run as root"
   exit 1
fi

function UID_GID_DUP_CHECK {
    dup_check=`egrep ":${uidno}:" /etc/passwd`
    if [ -z "$dup_check" ] ; then
        # so far so good, uid does not already exist in /etc/passwd
        dup_check=`egrep ":${uidno}:" /etc/group`
        if [ -z "$dup_check" ] ; then
           # so far so good, uid does not already exist in /etc/group
           echo
        else
            printf "\n    gid ${uidno} found in /etc/group.  Select a different uid."
            printf "    $dup_check"
            printf "\n    Quitting.\n\n"
            exit
        fi
    else
        printf "\n    uid ${uidno} found in /etc/password.  Select a different uid."
        printf "    $dup_check"
        printf "\n    Quitting.\n\n"
        exit
    fi
}

# Determine the actual user who is acting as root
parent_id=`ps -ef | grep $0 | awk '{ print $3 }'| head -n1`
# echo "parent id = $parent_id"
originating_user=`ps -ef |grep $parent_id | grep -v root | awk '{print $1}'`
# echo "originating_user = $originating_user"
while [ -z $originating_user ] ; do
    # No originating user found, try parent pid
    parent_id=`ps -ef | grep $parent_id | awk '{ print $3 }'| head -n1`
    # echo "parent id = $parent_id"
    originating_user=`ps -ef |grep $parent_id | grep -v root | awk '{print $1}'`
    # echo "originating_user = $originating_user"
done

local_user=$originating_user

# get the uid for the originating user:
user1_uid=`grep $local_user /etc/passwd | awk -F: '{ print $3 }'`
echo "$local_user has uid $user1_uid"
length_uid=${#user1_uid}
echo "length_uid = $length_uid"
echo "Checking available UIDs starting with UID $user1_uid"

# uids = 
echo "These UIDS are already claimed:"
for i in `cat /etc/passwd | awk -F: '{ print $3 }'| sort -n`; do len=${#i}; if [ $len -eq $length_uid ]; then echo $i; fi; done

# Take the first sequential UID available.
end_loop=$(($user1_uid + 100))
echo "end_loop = $end_loop"
avail1=0
avail2=0
avail3=0
i=$user1_uid

while [ "$i" -le "$end_loop" ]; do
    in_passwd=`grep ":${i}:" /etc/passwd |wc -l`
    in_group=`grep ":${i}:" /etc/group |wc -l`
    if (( $in_passwd == 0 )) ; then
        if (( $in_group == 0 )) ; then
            if (( $avail1 == 0 )) ; then
                avail1=$i
            elif (( $avail2 == 0 )); then 
                avail2=$i
            elif (( $avail3 == 0 )); then 
                avail3=$i
            else 
                break
            fi
        fi
    fi
    i=$(($i + 1))
done

echo "These UIDs are available:  $avail1 $avail2 $avail3"

echo -n "Username (login) to add? "
read username
# make sure username does not already exist on system
dup_check=`egrep "^${username}:" /etc/passwd`
if [ -z "$dup_check" ] ; then
    # username is does not exist on this system.  Ok to proceed.
    echo
else
    printf "\n    Found this in /etc/password.  Already installed?  Pick a different username?\n"
    echo "    $dup_check"
    printf "\n    Quitting.\n\n"
    exit
fi
username=`echo "$username" | tr '[:upper:]' '[:lower:]'`

dup_check=`egrep -i "^${username}:" /etc/passwd`
if [ -z "$dup_check" ] ; then
    # username is does not exist on this system.  Ok to proceed.
    printf "\n    Username $username does not already exist in /etc/password.  Okay to proceed.\n\n"
else
    printf "\n    Found this in /etc/password:\n    $dup_check\n    Already installed?  Pick a different username?\n"
    printf "\n    Quitting.\n\n"
    exit
fi

uidno=$avail1
echo "In order to create user $username, with uid $uidno need additional info"
echo -n "Is uid $uidno acceptable? [Y|n]: "
read okay_uid
ok_uid=`echo "$okay_uid" | tr '[:lower:]' '[:upper:]'`
if [[ "$ok_uid" !=  "Y" ]] ; then
    echo "Please provide acceptable uid number: "
    read uidno
    UID_GID_DUP_CHECK
fi

echo -n "First Name? "
read fname
fname=`echo "$fname" | tr '[:upper:]' '[:lower:]'`
fname="$(tr '[:lower:]' '[:upper:]' <<< ${fname:0:1})${fname:1}"
echo -n "Last Name? "
read lname
lname=`echo "$lname" | tr '[:upper:]' '[:lower:]'`
lname="$(tr '[:lower:]' '[:upper:]' <<< ${lname:0:1})${lname:1}"

echo -n "Primary Group? (enter to create $username as primary group) "
read groupone
if [ -z "$groupone" ] ; then
   # create group same as username if no Primary Group has been selected
   echo "adding group $username with gid $uidno"
   groupadd -g $uidno $username
   groupone=$username
else
   # make sure selected group exists
   Q=`egrep "^${groupone}" /etc/group`
   if [ -z "$Q" ] ; then
       # The group needs to exist before the user can be added to it
       printf "\n    Group \'$groupone\' does not exist.  Create it first!"
       printf "\n    Quitting\n\n."
       exit
   fi
fi

echo -n "Secondary Groups? (space delimited) ? "
read moregroups

echo -n "Create home directory? [Y|n]: " 
read mkhome
mkhome=`echo "$mkhome" | tr '[:lower:]' '[:upper:]'`
if [[ "$mkhome" !=  "Y" ]] ; then
    mkhome="-m"
else
    mkhome="-M"
fi

groups2=$(echo $moregroups | tr " " ",")

useradd -c "$fname $lname" -u $uidno -g $groupone -d ${HOMEBASE}/${username} -s $MYSHELL  $mkhome $username

if [ -z "$groups2" ] ; then
    # do nothing
    echo "No additional groups to add"
else
    usermod -a -G $groups2 $username
fi

printf "\n    Done.  REMEMBER TO SET A PASSWORD\n\n"