Support /etc/sysctl.d/ for Debian-based systems

On Debian-based systems, /etc/sysctl.conf doesn't exist and
/etc/sysctl.d/ directory is used instead. Modified xcatconfig
to prefer /etc/sysctl.d/99-xcat.conf when the directory exists,
falling back to /etc/sysctl.conf for backward compatibility.

Author: kcgthb

xCAT-server/sbin/xcatconfig

@@ -623,7 +623,7 @@ exit;
 #-----------------------------------------------------------------------------
 
 =head3    usage
-	
+
 	Displays message for -h option
 
 =cut
@@ -652,7 +652,7 @@ sub verbose
 #-----------------------------------------------------------------------------
 
 =head3    genSSHRootKeys
-	
+
      Will generate a new ssh rsa key for the root user, if it does not exist or if requested by the input -k flag.
 
 =cut
@@ -833,7 +833,7 @@ sub genSSHRootKeys
 #-----------------------------------------------------------------------------
 
 =head3   settunables
-	
+
     Will set the default suggested tunables on the Management Node or service node for Linux
 
 =cut
@@ -867,30 +867,50 @@ sub settunables
     }
 
     # set for after reboot
-    if (!(-f "/etc/sysctl.conf.xcatbackup")) {    # not already backed up
-        $cmd = "cp /etc/sysctl.conf /etc/sysctl.conf.xcatbackup";
+    my $sysctl_file;
+    if (-d "/etc/sysctl.d") {
+        $sysctl_file = "/etc/sysctl.d/99-xcat.conf";
+        if (!(-f "$sysctl_file")) {
+            $cmd = "touch $sysctl_file";
+            my $outref = xCAT::Utils->runcmd("$cmd", 0);
+            if ($::RUNCMD_RC != 0)
+            {
+                xCAT::MsgUtils->message('E', "Could not create $sysctl_file.");
+                exit 1;
+            }
+        }
+    } elsif (-f "/etc/sysctl.conf") {
+        $sysctl_file = "/etc/sysctl.conf";
+    } else {
+        xCAT::MsgUtils->message('E', "Could not find /etc/sysctl.d directory or /etc/sysctl.conf.");
+        exit 1;
+    }
+
+    my $sysctl_backup = "$sysctl_file.xcatbackup";
+    if (!(-f "$sysctl_backup")) {
+        $cmd = "cp $sysctl_file $sysctl_backup";
         my $outref = xCAT::Utils->runcmd("$cmd", 0);
         if ($::RUNCMD_RC != 0)
         {
-            xCAT::MsgUtils->message('E', "Could not backup /etc/sysctl.conf.");
+            xCAT::MsgUtils->message('E', "Could not backup $sysctl_file.");
             exit 1;
         }
     }
 
     #delete all occurance of the attribute and then add xCAT settings
-    `sed -i '/net.ipv4.neigh.default.gc_thresh1 /'d /etc/sysctl.conf`;
-    `echo "net.ipv4.neigh.default.gc_thresh1 = 1024" >>/etc/sysctl.conf`;
-    `sed -i '/net.ipv4.neigh.default.gc_thresh2 /'d /etc/sysctl.conf`;
-    `echo "net.ipv4.neigh.default.gc_thresh2 = 4096" >>/etc/sysctl.conf`;
-    `sed -i '/net.ipv4.neigh.default.gc_thresh3 /'d /etc/sysctl.conf`;
-    `echo "net.ipv4.neigh.default.gc_thresh3 = 8192" >>/etc/sysctl.conf`;
+    `sed -i '/net.ipv4.neigh.default.gc_thresh1 /'d $sysctl_file`;
+    `echo "net.ipv4.neigh.default.gc_thresh1 = 1024" >>$sysctl_file`;
+    `sed -i '/net.ipv4.neigh.default.gc_thresh2 /'d $sysctl_file`;
+    `echo "net.ipv4.neigh.default.gc_thresh2 = 4096" >>$sysctl_file`;
+    `sed -i '/net.ipv4.neigh.default.gc_thresh3 /'d $sysctl_file`;
+    `echo "net.ipv4.neigh.default.gc_thresh3 = 8192" >>$sysctl_file`;
 
 }
 
 #-----------------------------------------------------------------------------
 
 =head3    genSSHNodeHostKey
-	
+
   If node private node hostkeys do not exist in either directory or force option
    or generate host key option, we need to generate them
    These keys are installed on the nodes in /etc/ssh directory and allow the
@@ -1069,7 +1089,7 @@ sub is_redhat6sp4
 #-----------------------------------------------------------------------------
 
 =head3    initDB
-	
+
     Will initialize the DB if it does not already exist,  also updates with
 	new data needed or database changes during xCAT  install.
 
@@ -1526,7 +1546,7 @@ sub initDB
 #-----------------------------------------------------------------------------
 
 =head3    check for otherpkgs
-	
+
     Check to see if other pkgs exists in postscripts table.
 	If it does not we will be putting it in postbootscripts
           return exist_flag
@@ -1577,7 +1597,7 @@ sub checkotherpkgs
 #-----------------------------------------------------------------------------
 
 =head3    genCredentials
-	
+
     Will generate the xCAT credential,  if new install or requested to
 	regenerate.
 
@@ -1800,7 +1820,7 @@ sub setupAIXIPMITool
 #-----------------------------------------------------------------------------
 
 =head3    setupAIXexports
-	
+
     Set AIX exports
 
 =cut
@@ -1836,7 +1856,7 @@ sub setupAIXexports
 #-----------------------------------------------------------------------------
 
 =head3    setupLinuxexports
-	
+
     Set Linux exports
 
 =cut
@@ -1959,7 +1979,7 @@ sub setupLinuxexports
 #-----------------------------------------------------------------------------
 
 =head3    mknb
-	
+
    Creates a network boot root image on Linux
    Run mknb to put xCAT-genesis-scripts-x86_64 and xCAT-genesis-base-x86_64 together and in /tftpboot
    From 2.12.2, both xCAT-genesis-scripts-x86_64 and xCAT-genesis-scripts-ppc64 will be installed.
@@ -2003,7 +2023,7 @@ sub mknb
 #-----------------------------------------------------------------------------
 
 =head3    makenetworks
-	
+
      Runs makenetworks on AIX and Linux
 
 =cut
@@ -2030,7 +2050,7 @@ sub makenetworks
 #-----------------------------------------------------------------------------
 
 =head3    setuphttp
-	
+
      initializes http  on Linux
 
 =cut
@@ -2102,7 +2122,7 @@ sub setuphttp
 #-----------------------------------------------------------------------------
 
 =head3   cleanupPSTable
-	
+
    Any line in the postscripts table that has the following
    entry will have xcatserver,xcatclient remove because they
    are not called by servicenode
@@ -2214,7 +2234,7 @@ sub cleanupPSTable
 #-----------------------------------------------------------------------------
 
 =head3   setupMNinDB
-	
+
  Will add the management node to the noderes table with group=__mgmtnode
  Will add the management node to the servicenode tble with group=__mgmtnode
 
@@ -2315,7 +2335,7 @@ sub setupMNinDB
 #-----------------------------------------------------------------------------
 
 =head3    startnamedonboot
-	
+
      Configure named to start on boot
 
 =cut