global interfaces explorer: only check if we have ip or ifconfig and be more compatible.

tests on debian, centos, freebsd, openbsd, netbsd and solaris confirm that this is enough and extra os check is not needed here.

cdist/conf/explorer/interfaces

@@ -1,6 +1,6 @@
-#!/bin/sh
+#!/bin/sh -e
 #
-# 2012 Sébastien Gross <seb•ɑƬ•chezwam•ɖɵʈ•org>
+# 2019 Ander Punnar (ander-at-kvlt-dot-ee)
 #
 # This file is part of cdist.
 #
@@ -17,35 +17,14 @@
 # You should have received a copy of the GNU General Public License
 # along with cdist. If not, see <http://www.gnu.org/licenses/>.
 #
-#
-# List all network interfaces in explorer/ifaces. One interface per line.
-#
-# If your OS is not supported please provide a ifconfig output
-#
 
-# Use ip, if available
-if command -v ip >/dev/null; then
+if command -v ip > /dev/null
+then
     ip -o link show | sed -n 's/^[0-9]\+: \(.\+\): <.*/\1/p'
-    exit 0
+
+elif command -v ifconfig > /dev/null
+then
+    ifconfig -a \
+        | sed -n -E 's/^(.*)(:[[:space:]]*flags=|Link encap).*/\1/p' \
+        | sort -u
 fi
-
-if ! command -v ifconfig >/dev/null; then
-   # no ifconfig, nothing we could do
-   exit 0
-fi
-
-uname_s="$(uname -s)"
-REGEXP='s/^(.*)(:[[:space:]]*flags=|Link encap).*/\1/p'
-
-case "$uname_s" in
-    Darwin)
-	ifconfig -a | sed -n -E "$REGEXP"
-	;;
-    Linux|*BSD)
-	ifconfig -a | sed -n -r "$REGEXP"
-	;;
-    *)
-	echo "Unsupported ifconfig output for $uname_s" >&2
-	exit 1
-	;;
-esac