16927 FIX lnx_bonding failing with 'head: *: No such file or directory' if no bonding interface is configured

CMK-32474

closes: #900

Change-Id: Icaece69306a5be172ee49218e288aae15fef78fa

Author: osedlbauer

.werks/16927.md

@@ -0,0 +1,24 @@
+[//]: # (werk v3)
+# lnx_bonding failing with 'head: *: No such file or directory' if no bonding interface is configured
+
+key        | value
+---------- | ---
+date       | 2026-07-22T07:20:07.799324+00:00
+version    | 3.0.0b1
+class      | fix
+edition    | community
+component  | checks
+level      | 1
+compatible | yes
+
+The Linux and OpenWrt agents collect bonding information by reading the files
+in <tt>/proc/net/bonding</tt>. This directory exists whenever the bonding
+kernel module is loaded, even if no bonding interface is actually configured.
+
+In that case the directory is empty, and the agent tried to run
+<tt>head</tt> on an unmatched shell glob. This wrote an error such as
+<tt>head: ./*: No such file or directory</tt> to the agent output.
+
+The agents now only read the bonding files when at least one bonding
+interface is present, so no spurious error is emitted.
+

agents/check_mk_agent.linux

@@ -903,7 +903,7 @@ section_bonding_interfaces() {
     (
         cd /proc/net/bonding 2>/dev/null || return
         echo '<<<lnx_bonding:sep(58)>>>'
-        head -v -n 1000 ./*
+        [ -n "$(ls)" ] && head -v -n 1000 ./*
     )
 }
 

agents/check_mk_agent.openwrt

@@ -581,7 +581,7 @@ section_bonding_interfaces() {
     (
         cd /proc/net/bonding 2>/dev/null || return
         echo '<<<lnx_bonding:sep(58)>>>'
-        head -v -n 1000 ./*
+        [ -n "$(ls)" ] && head -v -n 1000 ./*
     )
 }