rc.sysinit: fix log writing to file in non debug mode to prevent writing to read-only filesystem

etc/rc.d/init.d/rc.sysinit

@@ -42,18 +42,15 @@ for cmd in $CMDLINE; do
    esac
 done
 
-[ $debug -gt 0 ] && logfile="/dev/console"
+[ $debug -gt 0 ] && logfile="/dev/console" || logfile="/dev/null"
 
-[ $logfile ] || {
-   logfile="/dev/.sysinit.start"
-   > $logfile
-}
 
 if [ ! -d $rc_base/rc$runlevel.d ]; then
    echo $"$rc_base/rc$runlevel.d does not exist"
    exit 1
 fi
 
+
 # set dns-resolving safe hostname for sysinit to successfully run
 hostname localhost
 
@@ -62,6 +59,11 @@ startservicesnum=`echo $startservices | wc -w`
 
 i=0
 for servicefile in $startservices; do
+   # write log to file as soon as writable filesystem is available
+   [ $logfile = "/dev/null" -a -w "/run" ] && {
+      logfile="/run/.sysinit.start"
+      > $logfile
+   }
    if [ "$previous" != "N" ]; then
       service=${servicefile#$rc_base/rc$runlevel.d/S$rex}
       stop=$rc_base/rc$runlevel.d/K$rex$service
@@ -74,7 +76,6 @@ for servicefile in $startservices; do
    progress=`expr 5 + $i \* 45 / $startservicesnum`
 
    $PLYMOUTH update --status="$progress"
-
    if [ "$service" = "postplug" ]; then
       $servicefile start
    else