rename-user

#!/bin/bash
#
# rename-user - rename a user (login name) along with its group and home dir
#
#    Copyright (C) 2015 Rodrigo Silva (MestreLion) <linux@rodrigosilva.com>
#
#    This program is free software: you can redistribute it and/or modify
#    it under the terms of the GNU General Public License as published by
#    the Free Software Foundation, either version 3 of the License, or
#    (at your option) any later version.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License
#    along with this program. See <http://www.gnu.org/licenses/gpl.html>
#
# TODO:
# - Fix files containing OLDHOME
# - Fix symlinks pointing to OLDHOME (or inside)

myname="${0##*/}"
mydir=$(dirname "$(readlink -f "$0")")
prefix=/home
verbose=0
yes=0
force=0
movegroup=1
movehome=1
homeargs=()

newgroup=""
newhome=""

fatal()   { [[ "$1" ]] && echo "$myname: error: $1" >&2 ; exit ${2:-1} ; }
message() { ((verbose)) && printf "%s\n" "$1"; }
argerr()  { printf "%s: %s\n" "$myname" "${1:-error}" >&2 ; usage 1 ; }
invalid() { argerr "invalid argument: $1" ; }
missing() { argerr "missing ${2:+$2 }argument${1:+ from $1}." ; }

confirm()
{
	local message="$1"
	local yes=${2:-0}
	local default=NO
	local reply

	if ! ((yes)); then
		read -p "$message (y/n, default $default): " reply
		reply="${reply:-$default}"
		case "$reply" in
		[Yy]*) ;;
		*    ) message "cancelled by user"; return 2;;
		esac
	fi
	return 0
}


usage() {
	cat <<-USAGE
	Usage: $myname [options] NEWNAME [OLDNAME]
	USAGE
	if [[ "$1" ]] ; then
		cat >&2 <<- USAGE
		Try '$myname --help' for more information.
		USAGE
		exit 1
	fi
	cat <<-USAGE

	Rename a user, including its home dir and default group.
	A wrapper to automate usermod/groupmod with extra validations.

	Options:
	  -h|--help       - show this page.
	  -v|--verbose    - print more details about what is being done.
	  -y|--yes        - do not prompt for confirmation.
	  -f|--force      - allow rename to existing home directory or group.
	  -D|--no-homedir - do not rename home directory.
	  -G|--no-group   - do not rename primary group.

	  -d|--homedir PATH
	                  - move current home directory to a custom PATH.
	                    By default if its last path component matches OLDNAME
	                    home is moved to 'basename <current home>/NEWNAME'.
	                    Ignored if --no-homedir is set.

	  -g|--group NAME
	                  - rename primary group to custom NAME. By default if
	                    group name matches OLDNAME it is renamed to NEWNAME.
	                    Ignored if --no-group is set.

	Notes:
	- Renaming 'root' or a currently logged in user is not allowed.

	- Renaming to an existing user is not allowed.

	- Moving home directory dir or renaming primary group to existing ones
	  is only allowed if --force is set.

	- Does not work (yet) for encripted home directories.

	Copyright (C) 2015 Rodrigo Silva (MestreLion) <linux@rodrigosilva.com>
	License: GPLv3 or later. See <http://www.gnu.org/licenses/gpl.html>
	USAGE
	exit 0
}

# Option handling
args=()
for arg in "$@"; do [[ "$arg" == "-h" || "$arg" == "--help" ]] && usage ; done
while (( $# )); do
	case "$1" in
	-v|--verbose    ) verbose=1            ;;
	-y|--yes        ) yes=1                ;;
	-f|--force      ) force=1              ;;
	-D|--no-homedir ) movehome=0           ;;
	-G|--no-group   ) movegroup=0          ;;
	-d|--homedir    ) shift ; newhome="$1" ;;
	-g|--group      ) shift ; newgroup="$1";;
	--home=*        ) newhome="${1#*=}"    ;;
	--group=*       ) newgroup="${1#*=}"   ;;
	-*              ) invalid "$1"         ;;
	*               ) args+=( "$1" )       ;;
	esac
	shift
done
if ((${#args[@]} >= 3)); then invalid "${args[2]}"; fi


# Name check

newname=${args[0]}
oldname=${args[1]:-"$USER"}

if [[ -z "$oldname" ]]; then missing "" "OLDNAME"; fi
if [[ -z "$newname" ]]; then missing "" "NEWNAME"; fi

if [[ "$oldname" == "root" ]]; then
	fatal "renaming 'root' is not allowed."
fi

if cut -d: -f1 /etc/passwd | grep -qxm1 "$newname"; then
	fatal "new user '$newname' already exists."
fi

if ! cut -d: -f1 /etc/passwd | grep -qxm1 "$oldname"; then
	fatal "user '$oldname' does not exist."
fi

if users | grep -qwm1 "$oldname"; then
	fatal "user '$oldname' is currently logged in."
fi


# Home check

oldhome=$(awk -F: -v name="$oldname" '$1 == name {print $6; exit}' /etc/passwd)

if ((movehome)); then
	if [[ -z "$newhome" ]]; then
		homebase=$(dirname "$oldhome")
		homedir=$(basename "$oldhome")
		if [[ "$homedir" == "$oldname" ]]; then
			newhome="$homebase"/"$newname"
		else
			newhome=$oldhome
		fi
	fi
	if [[ "$newhome" != "$oldhome" ]]; then
		homeargs=(-d "$newhome" -m)
	else
		homeargs=()
		movehome=0
	fi
	if !((force)) && ((movehome)) &&
	  [[ -e "$newhome" ]]; then
		fatal "new homedir '$newhome' already exists. Use --homedir to set a different one or --force to use it anyway."
	fi
else
	newhome=$oldhome
	homeargs=()
fi



# Group check

oldgroup=$(groups "$oldname" | cut -d' ' -f3)

if ((movegroup)); then
	if [[ -z "$newgroup" ]]; then
		if [[ "$oldgroup" == "$oldname" ]]; then
			newgroup=$newname
		else
			movegroup=0
		fi
	fi
	if !((force)) && ((movegroup)) &&
	  cut -d: -f1 /etc/group | grep -qxm1 "$newgroup"; then
		fatal "new group '$newgroup' already exists. Use --group to set a different one or --force to use it anyway."
	fi
else
	newgroup=$oldgroup
fi

message "Old user:"
message "Login: $oldname"
message "Group: $oldgroup"
message "Home:  $oldhome"
message ""
message "New user:"
message "Login: $newname"
message "Group: $newgroup"
message "Home:  $newhome"
message ""

if !((yes)) && ! confirm "Rename user '$oldname' to '$newname'?"; then
	exit
fi

sudo usermod -l "$newname" "${homeargs[@]}" "$oldname"
if ((movegroup)); then
	sudo groupmod -n "$newgroup" "$oldgroup"
fi

if ((movehome)); then
	message "Listing all files containing old home '$oldhome'. This may take a while..."
	find "$newhome" -lname "$oldhome"   2>/dev/null
	find "$newhome" -lname "$oldhome/*" 2>/dev/null
	grep --color -sr "$oldhome" /
fi

exit

#At the start screen press Ctrl+ALT+F1.
#Log in using your username and password.
#Set a password for the "root" account.
#sudo passwd root
#Log out.
#exit
#Log in using the "root" account and the password you have previously set.
#Change the username and the home folder to the new name that you want.
#usermod -l <newname> -d /home/<newname> -m <oldname>
#Change the group name to the new name that you want.
#groupmod -n <newgroup> <oldgroup>
#Lock the "root" account.
#passwd -l root
#better yet: passwd -d root
#If you were using ecryptfs (encrypted home directory).
#	Mount your encrypted directory using ecryptfs-recover-private and
#	edit <mountpoint>/.ecryptfs/Private.mnt to reflect your new home directory.
#Log out.
#exit
#press Ctrl+ALT+F7.