diff --git a/cmd/zed/zed.d/statechange-led.sh b/cmd/zed/zed.d/statechange-led.sh
index c1a1bd92d543..6484b79592aa 100755
--- a/cmd/zed/zed.d/statechange-led.sh
+++ b/cmd/zed/zed.d/statechange-led.sh
@@ -165,7 +165,7 @@ process_pool()
 	fi
 }
 
-if [ ! -z "$ZEVENT_VDEV_ENC_SYSFS_PATH" ] && [ ! -z "$ZEVENT_VDEV_STATE_STR" ] ; then
+if [ -n "$ZEVENT_VDEV_ENC_SYSFS_PATH" ] && [ -n "$ZEVENT_VDEV_STATE_STR" ] ; then
 	# Got a statechange for an individual VDEV
 	val=$(state_to_val "$ZEVENT_VDEV_STATE_STR")
 	vdev=$(basename "$ZEVENT_VDEV_PATH")
diff --git a/cmd/zed/zed.d/zed-functions.sh b/cmd/zed/zed.d/zed-functions.sh
index fb16e9d36f32..a6e608573e58 100644
--- a/cmd/zed/zed.d/zed-functions.sh
+++ b/cmd/zed/zed.d/zed-functions.sh
@@ -434,7 +434,7 @@ zed_guid_to_pool()
 	fi
 
 	guid=$(printf "%llu" "$1")
-	if [ ! -z "$guid" ] ; then
+	if [ -n "$guid" ] ; then
 		$ZPOOL get -H -ovalue,name guid | awk '$1=='"$guid"' {print $2}'
 	fi
 }
diff --git a/cmd/zpool/zpool.d/smart b/cmd/zpool/zpool.d/smart
index 64b5f6e4e4bc..bd18e9d0443c 100755
--- a/cmd/zpool/zpool.d/smart
+++ b/cmd/zpool/zpool.d/smart
@@ -69,7 +69,7 @@ if [ "$1" = "-h" ] ; then
         exit
 fi
 
-smartctl_path=$(which smartctl)
+smartctl_path=$(command -v smartctl)
 
 if [ -b "$VDEV_UPATH" ] && [ -x "$smartctl_path" ] || [ -n "$samples" ] ; then
 	if [ -n "$samples" ] ; then
@@ -228,7 +228,7 @@ smart_test)
 esac
 
 with_vals=$(echo "$out" | grep -E "$scripts")
-if [ ! -z "$with_vals" ]; then
+if [ -n "$with_vals" ]; then
 	echo "$with_vals"
 	without_vals=$(echo "$scripts" | tr "|" "\n" |
 		grep -v -E "$(echo "$with_vals" |
@@ -237,6 +237,6 @@ else
 	without_vals=$(echo "$scripts" | tr "|" "\n" | awk '{print $0"="}')
 fi
 
-if [ ! -z "$without_vals" ]; then
+if [ -n "$without_vals" ]; then
 	echo "$without_vals"
 fi
diff --git a/scripts/zimport.sh b/scripts/zimport.sh
index 426c329c9e1e..d7e82fe9f025 100755
--- a/scripts/zimport.sh
+++ b/scripts/zimport.sh
@@ -233,8 +233,8 @@ src_set_vars() {
 	ZFS_URL="$REPO/zfs/tarball/$ZFS_TAG"
 
 	if [ "$TAG" = "installed" ]; then
-		ZPOOL_CMD=$(which zpool)
-		ZFS_CMD=$(which zfs)
+		ZPOOL_CMD=$(command -v zpool)
+		ZFS_CMD=$(command -v zfs)
 		ZFS_SH="/usr/share/zfs/zfs.sh"
 	else
 		ZPOOL_CMD="./cmd/zpool/zpool"