diff --git a/usr.sbin/adduser/adduser.sh b/usr.sbin/adduser/adduser.sh
--- a/usr.sbin/adduser/adduser.sh
+++ b/usr.sbin/adduser/adduser.sh
@@ -34,7 +34,7 @@
 #
 err() {
 	if [ -z "$quietflag" ]; then
-		echo 1>&2 ${THISCMD}: ERROR: $*
+		echo 1>&2 "${THISCMD}: ERROR: $*"
 	fi
 }
 
@@ -43,7 +43,7 @@
 #
 info() {
 	if [ -z "$quietflag" ]; then
-		echo ${THISCMD}: INFO: $*
+		echo "${THISCMD}: INFO: $*"
 	fi
 }
 
@@ -58,10 +58,10 @@
 	_nextuid=
 
 	if [ -z "$_uid" ]; then
-		_nextuid="`${PWCMD} usernext | cut -f1 -d:`"
+		_nextuid="$(${PWCMD} usernext | cut -f1 -d:)"
 	else
 		while : ; do
-			${PWCMD} usershow $_uid > /dev/null 2>&1
+			${PWCMD} usershow "$_uid" > /dev/null 2>&1
 			if [ ! "$?" -eq 0 ]; then
 				_nextuid=$_uid
 				break
@@ -69,7 +69,7 @@
 			_uid=$(($_uid + 1))
 		done
 	fi
-	echo $_nextuid
+	echo "$_nextuid"
 }
 
 # show_usage
@@ -104,13 +104,13 @@
 #
 valid_shells() {
 	_prefix=
-	cat ${ETCSHELLS} |
+	cat "${ETCSHELLS}" |
 	while read _path _junk ; do
 		case $_path in
 		\#*|'')
 			;;
 		*)
-			echo -n "${_prefix}`basename $_path`"
+			echo -n "${_prefix}$(basename "$_path")"
 			_prefix=' '
 			;;
 		esac
@@ -140,15 +140,15 @@
 		return 0;
 	fi
 
-	cat ${ETCSHELLS} |
+	cat "${ETCSHELLS}" |
 	while read _path _junk ; do
 		case "$_path" in
 		\#*|'')
 			;;
 		*)
 			if [ "$_path" = "$_shell" -o \
-			    "`basename $_path`" = "$_shell" ]; then
-				echo $_path
+			    "$(basename "$_path")" = "$_shell" ]; then
+				echo "$_path"
 				return 0
 			fi
 			;;
@@ -169,7 +169,7 @@
 	_sh="$1"
 	_shellchk="${GREPCMD} '^$_sh$' ${ETCSHELLS} > /dev/null 2>&1"
 
-	if ! eval $_shellchk; then
+	if ! eval "$_shellchk"; then
 		# The nologin shell is not listed in /etc/shells.
 		if [ "$_sh" != "${NOLOGIN_PATH}" ]; then
 			err "Invalid shell ($_sh) for user $username."
@@ -188,21 +188,21 @@
 #	      it makes sense to save.
 #
 save_config() {
-	echo "# Configuration file for adduser(8)."     >  ${ADDUSERCONF}
-	echo "# NOTE: only *some* variables are saved." >> ${ADDUSERCONF}
-	echo "# Last Modified on `${DATECMD}`."		>> ${ADDUSERCONF}
-	echo ''				>> ${ADDUSERCONF}
-	echo "defaultHomePerm=$uhomeperm" >> ${ADDUSERCONF}
-	echo "defaultLgroup=$ulogingroup" >> ${ADDUSERCONF}
-	echo "defaultclass=$uclass"	>> ${ADDUSERCONF}
-	echo "defaultgroups=$ugroups"	>> ${ADDUSERCONF}
-	echo "passwdtype=$passwdtype" 	>> ${ADDUSERCONF}
-	echo "homeprefix=$homeprefix" 	>> ${ADDUSERCONF}
-	echo "defaultshell=$ushell"	>> ${ADDUSERCONF}
-	echo "udotdir=$udotdir"		>> ${ADDUSERCONF}
-	echo "msgfile=$msgfile"		>> ${ADDUSERCONF}
-	echo "disableflag=$disableflag" >> ${ADDUSERCONF}
-	echo "uidstart=$uidstart"       >> ${ADDUSERCONF}
+	echo "# Configuration file for adduser(8)."     >  "${ADDUSERCONF}"
+	echo "# NOTE: only *some* variables are saved." >> "${ADDUSERCONF}"
+	echo "# Last Modified on $(${DATECMD})."		>> "${ADDUSERCONF}"
+	echo ''				>> "${ADDUSERCONF}"
+	echo "defaultHomePerm=$uhomeperm" >> "${ADDUSERCONF}"
+	echo "defaultLgroup=$ulogingroup" >> "${ADDUSERCONF}"
+	echo "defaultclass=$uclass"	>> "${ADDUSERCONF}"
+	echo "defaultgroups=$ugroups"	>> "${ADDUSERCONF}"
+	echo "passwdtype=$passwdtype" 	>> "${ADDUSERCONF}"
+	echo "homeprefix=$homeprefix" 	>> "${ADDUSERCONF}"
+	echo "defaultshell=$ushell"	>> "${ADDUSERCONF}"
+	echo "udotdir=$udotdir"		>> "${ADDUSERCONF}"
+	echo "msgfile=$msgfile"		>> "${ADDUSERCONF}"
+	echo "disableflag=$disableflag" >> "${ADDUSERCONF}"
+	echo "uidstart=$uidstart"       >> "${ADDUSERCONF}"
 }
 
 # add_user
@@ -288,7 +288,7 @@
 	_pwcmd="$_pwcmd $_shell $_class $_home $_dotdir $_passwdmethod $_passwd"
 	_pwcmd="$_pwcmd $_expire $_pwexpire"
 
-	if ! _output=`eval $_pwcmd` ; then
+	if ! _output=$(eval "$_pwcmd") ; then
 		err "There was an error adding user ($username)."
 		return 1
 	else
@@ -300,7 +300,7 @@
 	fi
 
 	if [ -n "$disableflag" ]; then
-		if ${PWCMD} lock $username ; then
+		if ${PWCMD} lock "$username" ; then
 			info "Account ($username) is locked."
 		else
 			info "Account ($username) could NOT be locked."
@@ -317,10 +317,10 @@
 			# be empty if it's writeable only by the owner. _owner
 			# will *NOT* be empty if the file is owned by root.
 			#
-			_dir="`dirname $msgfile`"
-			_file="`basename $msgfile`"
-			_perms=`/usr/bin/find $_dir -name $_file -perm +07022 -prune`
-			_owner=`/usr/bin/find $_dir -name $_file -user 0 -prune`
+			_dir="$(dirname "$msgfile")"
+			_file="$(basename "$msgfile")"
+			_perms=$(/usr/bin/find "$_dir" -name "$_file" -perm +07022 -prune)
+			_owner=$(/usr/bin/find "$_dir" -name "$_file" -user 0 -prune)
 			if [ -z "$_owner" -o -n "$_perms" ]; then
 				err "The message file ($msgfile) may be writeable only by root."
 				return 1
@@ -328,7 +328,7 @@
 			cat "$msgfile" |
 			while read _line ; do
 				eval echo "$_line"
-			done | ${MAILCMD} -s"Welcome" ${username}
+			done | ${MAILCMD} -s"Welcome" "${username}"
 			info "Sent welcome message to ($username)."
 		}
 	fi
@@ -352,7 +352,7 @@
 			echo -n "Username: "
 			read _input
 		else
-			_input="`echo "$fileline" | cut -f1 -d:`"
+			_input="$(echo "$fileline" | cut -f1 -d:)"
 		fi
 
 		# There *must* be a username, and it must not exist. If
@@ -363,7 +363,7 @@
 			err "You must enter a username!"
 			[ -z "$fflag" ] && continue
 		fi
-		${PWCMD} usershow $_input > /dev/null 2>&1
+		${PWCMD} usershow "$_input" > /dev/null 2>&1
 		if [ "$?" -eq 0 ]; then
 			err "User exists!"
 			[ -z "$fflag" ] && continue
@@ -387,7 +387,7 @@
 		echo -n "Full name: "
 		read _input
 	else
-		_input="`echo "$fileline" | cut -f7 -d:`"
+		_input="$(echo "$fileline" | cut -f7 -d:)"
 	fi
 	ugecos="$_input"
 }
@@ -404,23 +404,23 @@
 
 	# Make sure the current value of the shell is a valid one
 	if [ -z "$Sflag" ]; then
-		if ! shell_exists $ushell ; then
+		if ! shell_exists "$ushell" ; then
 			info "Using default shell ${defaultshell}."
 			ushell="$defaultshell"
 		fi
 	fi
 
 	if [ -z "$fflag" ]; then
-		echo -n "Shell ($shells) [`basename $ushell`]: "
+		echo -n "Shell ($shells) [$(basename "$ushell")]: "
 		read _input
 	else
-		_input="`echo "$fileline" | cut -f9 -d:`"
+		_input="$(echo "$fileline" | cut -f9 -d:)"
 	fi
 	if [ -n "$_input" ]; then
 		if [ -n "$Sflag" ]; then
 			ushell="$_input"
 		else
-			_fullpath=`fullpath_from_shell $_input`
+			_fullpath=$(fullpath_from_shell "$_input")
 			if [ -n "$_fullpath" ]; then
 				ushell="$_fullpath"
 			else
@@ -442,7 +442,7 @@
 		echo -n "Home directory [${homeprefix}/${username}]: "
 		read _input
 	else
-		_input="`echo "$fileline" | cut -f8 -d:`"
+		_input="$(echo "$fileline" | cut -f8 -d:)"
 	fi
 
 	if [ -n "$_input" ]; then
@@ -451,7 +451,7 @@
 		# directory prefix. Otherwise it is understood to
 		# be $prefix/$user
 		#
-		[ -z "$configflag" ] && homeprefix="`dirname $uhome`" || homeprefix="$uhome"
+		[ -z "$configflag" ] && homeprefix="$(dirname "$uhome")" || homeprefix="$uhome"
 	else
 		uhome="${homeprefix}/${username}"
 	fi
@@ -490,7 +490,7 @@
 	_prompt=
 
 	if [ -n "$uuid" ]; then
-		uuid=`get_nextuid $uuid`
+		uuid=$(get_nextuid "$uuid")
 		_prompt="Uid [$uuid]: "
 	else
 		_prompt="Uid (Leave empty for default): "
@@ -499,11 +499,11 @@
 		echo -n "$_prompt"
 		read _input
 	else
-		_input="`echo "$fileline" | cut -f2 -d:`"
+		_input="$(echo "$fileline" | cut -f2 -d:)"
 	fi
 
 	[ -n "$_input" ] && uuid=$_input
-	uuid=`get_nextuid $uuid`
+	uuid=$(get_nextuid "$uuid")
 	uidstart=$uuid
 }
 
@@ -519,7 +519,7 @@
 		echo -n "Login class [$_class]: "
 		read _input
 	else
-		_input="`echo "$fileline" | cut -f4 -d:`"
+		_input="$(echo "$fileline" | cut -f4 -d:)"
 	fi
 
 	[ -n "$_input" ] && uclass="$_input"
@@ -540,7 +540,7 @@
 		echo -n "Login group [${ulogingroup:-$username}]: "
 		read _input
 	else
-		_input="`echo "$fileline" | cut -f3 -d:`"
+		_input="$(echo "$fileline" | cut -f3 -d:)"
 	fi
 
 	# Pw(8) will use the username as login group if it's left empty
@@ -572,8 +572,8 @@
 #	routine is used only from batch processing mode.
 #
 get_expire_dates() {
-	upwexpire="`echo "$fileline" | cut -f5 -d:`"
-	uexpire="`echo "$fileline" | cut -f6 -d:`"
+	upwexpire="$(echo "$fileline" | cut -f5 -d:)"
+	uexpire="$(echo "$fileline" | cut -f6 -d:)"
 }
 
 # get_password
@@ -680,7 +680,7 @@
 		get_logingroup
 		_logingroup_ok=yes
 		if [ -n "$ulogingroup" -a "$username" != "$ulogingroup" ]; then
-			if ! ${PWCMD} show group $ulogingroup > /dev/null 2>&1; then
+			if ! ${PWCMD} show group "$ulogingroup" > /dev/null 2>&1; then
 				echo "Group $ulogingroup does not exist!"
 				_logingroup_ok=no
 			fi
@@ -691,7 +691,7 @@
 		_groups_ok=yes
 		for i in $ugroups; do
 			if [ "$username" != "$i" ]; then
-				if ! ${PWCMD} show group $i > /dev/null 2>&1; then
+				if ! ${PWCMD} show group "$i" > /dev/null 2>&1; then
 					echo "Group $i does not exist!"
 					_groups_ok=no
 				fi
@@ -786,12 +786,12 @@
 		esac
 		break
 	done
-	
+
 	# Display the information we have so far and prompt to
 	# commit it.
 	#
 	_disable=${disableflag:-"no"}
-	[ -z "$configflag" ] && printf "%-10s : %s\n" Username $username
+	[ -z "$configflag" ] && printf "%-10s : %s\n" Username "$username"
 	case $passwdtype in
 	yes)
 		_pass='*****'
@@ -837,7 +837,7 @@
 
 #### END SUBROUTINE DEFINITION ####
 
-THISCMD=`/usr/bin/basename $0`
+THISCMD=$(/usr/bin/basename "$0")
 DEFAULTSHELL=/bin/sh
 ADDUSERCONF="${ADDUSERCONF:-/etc/adduser.conf}"
 PWCMD="${PWCMD:-/usr/sbin/pw}"
@@ -865,7 +865,7 @@
 ugroups=
 uexpire=
 upwexpire=
-shells="`valid_shells`"
+shells="$(valid_shells)"
 passwdtype="yes"
 msgfile=/etc/adduser.msg
 msgflag=
@@ -891,7 +891,7 @@
 # measure as much as it is a useful method of reminding the user to
 # 'su -' before he/she wastes time entering data that won't be saved.
 #
-procowner=${procowner:-`/usr/bin/id -u`}
+procowner=${procowner:-$(/usr/bin/id -u)}
 if [ "$procowner" != "0" ]; then
 	err 'you must be the super-user (uid 0) to use this utility.'
 	exit 1
@@ -912,10 +912,10 @@
 if [ -n "$readconfig" ]; then
 	# On a long-lived system, the first time this script is run it
 	# will barf upon reading the configuration file for its perl predecessor.
-	if ( . ${ADDUSERCONF} > /dev/null 2>&1 ); then
-		[ -r ${ADDUSERCONF} ] && . ${ADDUSERCONF} > /dev/null 2>&1
+	if ( . "${ADDUSERCONF}" > /dev/null 2>&1 ); then
+		[ -r "${ADDUSERCONF}" ] && . "${ADDUSERCONF}" > /dev/null 2>&1
 	fi
-fi 
+fi
 
 # Process command-line options
 #
@@ -999,7 +999,7 @@
 		shift
 		;;
 	-s)
-		defaultshell="`fullpath_from_shell $2`"
+		defaultshell="$(fullpath_from_shell "$2")"
 		shift; shift
 		;;
 	-S)
@@ -1021,7 +1021,7 @@
 		input_from_file
 	elif [ -n "$infile" ]; then
 		if [ -r "$infile" ]; then
-			input_from_file < $infile
+			input_from_file < "$infile"
 		else
 			err "File ($infile) is unreadable or does not exist."
 		fi
@@ -1037,7 +1037,7 @@
 		read _input
 		case $_input in
 		[Yy][Ee][Ss]|[Yy][Ee]|[Yy])
-			uidstart=`get_nextuid $uidstart`
+			uidstart=$(get_nextuid "$uidstart")
 			input_interactive
 			continue
 			;;