wireless_channel_occupation_: various improvements

* add documentation header
* support dirty config
* fix shellcheck issues

plugins/network/wireless_channel_occupation_

@@ -1,28 +1,50 @@
 #!/bin/sh
-#
+
-# Monitor the wifi channel occupation (taken from "iw dev wlan0 survey dump").
+: << =cut
-#
+
-# Symlink this plugin with the name of the wifi interface added (e.g. "wlan0").
+=head1 NAME
-#
+
-#
+wireless_channel_occupation_ - Monitor occupation of wireless channels
-# Copyright (C) 2015 Lars Kruse <devel@sumpfralle.de>
+
-#
+
-#    This program is free software: you can redistribute it and/or modify
+=head1 APPLICABLE SYSTEMS
-#    it under the terms of the GNU General Public License as published by
+
-#    the Free Software Foundation, either version 3 of the License, or
+All systems with at least one wireless interface and the the tool "iw".
-#    (at your option) any later version.
+
-#
+The wifi channel occupation is parsed from the output of "iw dev wlan0 survey dump".
-#    This program is distributed in the hope that it will be useful,
+
-#    but WITHOUT ANY WARRANTY; without even the implied warranty of
+
-#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+=head1 CONFIGURATION
-#    GNU General Public License for more details.
+
-#
+Symlink this plugin with the name of the wifi interface added (e.g. "wlan0").
-#    You should have received a copy of the GNU General Public License
+
-#    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+Root permissions are probably required for accessing "iw".
-#
+
-# Magic markers
+  [wireless_channel_occupation_*]
-#%# capabilities=autoconf suggest
+  user root
-#%# family=auto
+
+
+=head1 VERSION
+
+  1.1
+
+
+=head1 AUTHOR
+
+Lars Kruse <devel@sumpfralle.de>
+
+
+=head1 LICENSE
+
+GPLv3 or above
+
+
+=head1 MAGIC MARKERS
+
+  #%# family=auto
+  #%# capabilities=autoconf suggest
+
+=cut
 
 set -eu
 
@@ -35,36 +57,26 @@ clean_fieldname() {
 }
 
 
-get_wifi_devices() {
+get_wifi_interfaces() {
 	iw dev | grep Interface | awk '{print $2}'
 }
 
-
 get_wifi_device_from_suffix() {
 	local suffix
-	local called
+	local real_dev
-	called=$(basename "$0")
+	# pick the part after the basename of the real file
-	suffix="${called#$SCRIPT_PREFIX}"
+	suffix=$(basename "$0" | sed "s/^$SCRIPT_PREFIX//")
-	# empty result if the prefix did not match (and was not removed)
+	for real_dev in $(get_wifi_interfaces); do
-	[ "$suffix" = "$0" ] && echo "" || echo "$suffix"
+		[ "$suffix" != "$(clean_fieldname "$real_dev")" ] || echo "$real_dev"
+	done | head -1
 }
 
 
-if [ "${1:-}" = "autoconf" ]; then
+do_config() {
-	if which iw 2>/dev/null; then
+	local device
-		if [ -n "$(get_wifi_devices)" ]; then
+	local dev_field
-			echo "yes"
-		else
-			echo "no (missing wifi devices)"
-		fi
-	else
-		echo "no (missing 'iw' dependency)"
-	fi
-elif [ "${1:-}" = "suggest" ]; then
-	get_wifi_devices
-elif [ "${1:-}" = "config" ]; then
 	device=$(get_wifi_device_from_suffix)
-	[ -z "$device" ] && echo >&2 "Invalid wifi device name given" && exit 1
+	[ -z "$device" ] && echo >&2 "Invalid wifi device name given" && return 1
 	echo "graph_title Channel Occupation of $device"
 	echo "graph_vlabel %"
 	echo "graph_category wireless"
@@ -93,13 +105,39 @@ elif [ "${1:-}" = "config" ]; then
 	echo "${dev_field}_transmit.type DERIVE"
 	echo "${dev_field}_transmit.draw STACK"
 	echo "${dev_field}_transmit.cdef 100,${dev_field}_transmit,${dev_field}_active,/,*"
-else
+}
+
+
+do_fetch() {
+	local device
 	device=$(get_wifi_device_from_suffix)
-	[ -z "$device" ] && echo >&2 "Invalid wifi device name given" && exit 1
+	[ -z "$device" ] && echo >&2 "Invalid wifi device name given" && return 1
 	iw dev "$device" survey dump \
 		| grep -F -A 5 "[in use]" \
 		| grep -E "channel (busy|receive|transmit|active) time:" \
-		| awk '{print "'${device}_'"$2"'.value'",$4}'
+		| awk '{print "'"${device}_"'"$2"'.value'",$4}'
+}
+
+
+if [ "${1:-}" = "autoconf" ]; then
+	if which iw >/dev/null; then
+		if [ -n "$(get_wifi_interfaces)" ]; then
+			echo "yes"
+		else
+			echo "no (missing wifi devices)"
+		fi
+	else
+		echo "no (missing 'iw' dependency)"
+	fi
+elif [ "${1:-}" = "suggest" ]; then
+	for dev in $(get_wifi_interfaces); do
+		clean_fieldname "$dev"
+	done
+elif [ "${1:-}" = "config" ]; then
+	do_config || exit 1
+	[ "${MUNIN_CAP_DIRTYCONFIG:-0}" = 1 ] && do_fetch
+else
+	do_fetch
 fi
 
 exit 0