Fix SC2181 ("[ $?") outside tests/

Reviewed-by: John Kennedy <john.kennedy@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Closes #12042

contrib/dracut/02zfsexpandknowledge/module-setup.sh.in

@@ -17,8 +17,7 @@ get_pool_devices() {
   local prefix
   local resolved
   poolconfigtemp=`mktemp`
-  @sbindir@/zpool list -v -H -P "$1" > "$poolconfigtemp" 2>&1
-  if [ "$?" != "0" ] ; then
+  if ! @sbindir@/zpool list -v -H -P "$1" > "$poolconfigtemp" 2>&1 ; then
     poolconfigoutput=$(cat "$poolconfigtemp")
     dinfo "zfsexpandknowledge: pool $1 cannot be listed: $poolconfigoutput"
   else

contrib/dracut/90zfs/mount-zfs.sh.in

@@ -38,11 +38,9 @@ modprobe zfs 2>/dev/null
 udevadm settle
 
 if [ "${root}" = "zfs:AUTO" ] ; then
-	ZFS_DATASET="$(find_bootfs)"
-	if [ $? -ne 0 ] ; then
+	if ! ZFS_DATASET="$(find_bootfs)" ; then
 		zpool import -N -a ${ZPOOL_IMPORT_OPTS}
-		ZFS_DATASET="$(find_bootfs)"
-		if [ $? -ne 0 ] ; then
+		if ! ZFS_DATASET="$(find_bootfs)" ; then
 			warn "ZFS: No bootfs attribute found in importable pools."
 			export_all -F
 

contrib/dracut/90zfs/zfs-lib.sh.in

@@ -5,12 +5,8 @@ command -v getargbool >/dev/null || {
     # Compatibility with older Dracut versions.
     # With apologies to the Dracut developers.
     getargbool() {
-        if ! [ -z "$_b" ]; then
-                unset _b
-        fi
         _default="$1"; shift
-        _b=$(getarg "$@")
-        [ $? -ne 0 ] &&  [ -z "$_b" ] && _b="$_default"
+        ! _b=$(getarg "$@") && [ -z "$_b" ] && _b="$_default"
         if [ -n "$_b" ]; then
             [ "$_b" = "0" ] && return 1
             [ "$_b" = "no" ] && return 1