Punt is_function in favour of POSIX shell builtin command, thanks to Harald van Dijk for the idea.

sh/functions.sh.in

@@ -20,15 +20,6 @@ eoutdent()
 	return 0
 }
 
-is_function()
-{
-	if [ -n "${BASH_VERSION}" ]; then
-		[ "$(type -t "$1")" = "function" ]
-	else
-		[ "$(type "$1" 2>/dev/null)" = "$1 is a shell function" ]
-	fi
-}
-
 yesno()
 {
 	[ -z "$1" ] && return 1

sh/net.sh.in

@@ -28,7 +28,7 @@ depend()
 		*) after net.lo net.lo0;;
 	esac
 
-	if is_function depend_${IFVAR}; then
+	if [ "$(command -v "depend_${IFVAR}")" = "depend_${IFVAR}" ]; then
 		depend_${IFVAR}
 	fi
 
@@ -344,7 +344,7 @@ _load_modules()
 		# Wrap our provides
 		local f=
 		for f in pre_start start post_start; do 
-			eval "${provides}_${f}() { is_function ${mod}_${f} || return 0; ${mod}_${f} \"\$@\"; }"
+			eval "${provides}_${f}() { [ "$(command -v "${mod}_${f}")" = "${mod}_${f}" ] || return 0; ${mod}_${f} \"\$@\"; }"
 		done
 
 		eval module_${mod}_provides="${provides}"
@@ -358,7 +358,7 @@ _load_modules()
 			eval x=\$module_${mod}_provides
 			[ -z "${x}" ] && continue
 			for f in pre_start start post_start; do 
-				eval "${x}_${f}() { is_function ${mod}_${f} || return 0; ${mod}_${f} \"\$@\"; }"
+				eval "${x}_${f}() { [ "$(command -v "${mod}_${f}")" = "${mod}_${f}" ] || return 0; ${mod}_${f} \"\$@\"; }"
 			done
 			eval module_${x}_providedby="${mod}"
 			;;
@@ -462,7 +462,7 @@ start()
 	# We up the iface twice if we have a preup to ensure it's up if
 	# available in preup and afterwards incase the user inadvertently
 	# brings it down
-	if is_function preup; then
+	if [ "$(command -v preup)" = "preup" ]; then
 		_up 2>/dev/null
 		ebegin "Running preup"
 		eindent
@@ -473,7 +473,7 @@ start()
 	_up 2>/dev/null
 	
 	for module in ${MODULES}; do
-		if is_function "${module}_pre_start"; then
+		if [ "$(command -v "${module}_pre_start")" = "${module}_pre_start"]; then
 			${module}_pre_start || exit $?
 		fi
 	done
@@ -522,7 +522,7 @@ start()
 			null) :;;
 			[0-9]*|*:*) _add_address ${config};;
 			*)
-				if is_function "${config}_start"; then
+				if [ "$(command -v "${config}_start")" = "${config}_start" ]; then
 					"${config}"_start
 				else
 					eerror "nothing provides \`${config}'"
@@ -547,7 +547,7 @@ start()
 	done
 
 	if ! ${oneworked}; then
-		if is_function failup; then
+		if [ "$(command -v failup)" = "failup" ]; then
 			ebegin "Running failup"
 			eindent
 			failup
@@ -600,12 +600,12 @@ ${routes}"
 	fi
 
 	for module in ${MODULES}; do
-		if is_function "${module}_post_start"; then
+		if [ "$(command -v "${module}_post_start")" = "${module}_post_start" ]; then
 			${module}_post_start || exit $?
 		fi
 	done
 
-	if is_function postup; then
+	if [ "$(command -v postup)" = "postup" ]; then
 		ebegin "Running postup"
 		eindent
 		postup 
@@ -628,7 +628,7 @@ stop()
 		_load_modules false
 	fi
 
-	if is_function predown; then
+	if [ "$(command -v predown)" = "predown" ]; then
 		ebegin "Running predown"
 		eindent
 		predown || return 1
@@ -641,24 +641,24 @@ stop()
 	fi
 
 	for module in ${MODULES}; do
-		if is_function "${module}_pre_stop"; then
+		if [ "$(command -v "${module}_pre_stop")" = "${module}_pre_stop" ]; then
 			${module}_pre_stop || exit $?
 		fi
 	done
 
 	for module in ${MODULES}; do
-		if is_function "${module}_stop"; then
+		if [ "$(command -v "${module}_stop")" = "${module}_stop" ]; then
 			${module}_stop
 		fi
 	done
 
 	# Only delete addresses for non PPP interfaces
-	if ! is_function is_ppp || ! is_ppp; then
+	if ! [ "$(command -v is_ppp)" = "is_ppp" ] || ! is_ppp; then
 		_delete_addresses "${IFACE}"
 	fi
 
 	for module in ${MODULES}; do
-		if is_function "${module}_post_stop"; then
+		if [ "$(command -v "${module}_post_stop")" = "${module}_post_stop" ]; then
 			${module}_post_stop
 		fi
 	done
@@ -669,7 +669,7 @@ stop()
 
 	type resolvconf >/dev/null 2>&1 && resolvconf -d "${IFACE}" 2>/dev/null
 
-	if is_function postdown; then
+	if [ "$(command -v "postdown")" = "postdown" ]; then
 		ebegin "Running postdown"
 		eindent
 		postdown

sh/runscript.sh.in

@@ -94,7 +94,7 @@ unset _f
 
 # If we have a default command then supply a default start function
 if [ -n "${command}" ]; then
-	if ! is_function start; then
+	if ! [ "$(command -v start)" != "start" ]; then
 		start() {
 			local _background=
 			ebegin "Starting ${name:-${RC_SVCNAME}}"
@@ -126,7 +126,7 @@ fi
 # If we have a default command, procname or pidfile then supply a default stop 
 # function
 if [ -n "${command}" -o -n "${procname}" -o -n "${pidfile}" ]; then
-	if ! is_function stop; then
+	if ! [ "$(command -v stop)" != "stop" ]; then
 		stop() {
 			ebegin "Stopping ${name:-${RC_SVCNAME}}"
 			start-stop-daemon --stop \
@@ -143,7 +143,7 @@ while [ -n "$1" ]; do
 	for _cmd in describe start stop ${extra_commands:-${opts}} \
 		${extra_started_commands}; do
 		if [ "${_cmd}" = "$1" ]; then
-			if is_function "$1"; then
+			if [ "$(command -v "$1")" = "$1" ]; then
 				# If we're in the background, we may wish to
 				# fake some commands. We do this so we can
 				# "start" ourselves from inactive which then
@@ -168,11 +168,11 @@ while [ -n "$1" ]; do
 					fi
 				done
 				unset _cmd
-				if is_function "$1"_pre >/dev/null 2>&1; then
+				if [ "$(command -v "$1_pre")" = "$1_pre" ]; then
 					"$1"_pre || exit $?
 				fi
 				"$1" || exit $?
-				if is_function "$1"_post >/dev/null 2>&1; then
+				if [ "$(command -v "$1_post")" = "$1_post" ]; then
 					"$1"_post || exit $?
 				fi
 				shift