[type/__sysctl] Fix on NetBSD

cdist/conf/type/__sysctl/explorer/value

@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/bin/sh -e
 #
 # 2014 Steven Armstrong (steven-cdist at armstrong.cc)
 #
@@ -18,5 +18,10 @@
 # along with cdist. If not, see <http://www.gnu.org/licenses/>.
 #
 
+if test "$(uname -s)" = NetBSD
+then
+	PATH=$(getconf PATH)
+fi
+
 # get the current runtime value
-sysctl -n "$__object_id" || true
+sysctl -n "${__object_id}" || true

cdist/conf/type/__sysctl/gencode-remote

@@ -44,6 +44,8 @@ case "$os" in
       flag='-w'
       ;;
    netbsd)
+      # shellcheck disable=SC2016
+      echo 'PATH=$(getconf PATH)'
       flag='-w'
       ;;
    freebsd|openbsd)

cdist/conf/type/__sysctl/man.rst

@@ -26,6 +26,13 @@ EXAMPLES
 
     __sysctl net.ipv4.ip_forward --value 1
 
+    # On some operating systems, e.g. NetBSD, to prevent an error if the
+    # MIB style name does not exist (e.g. optional kernel components),
+    # name and value can be separated by `?=`. The same effect can be achieved
+    # in cdist by appending a `?` to the key:
+
+    __sysctl ddb.onpanic? --value -1
+
 
 AUTHORS
 -------