disable xrootd log rotating

xcache.singularity.def

@@ -161,5 +161,5 @@ fi
 export LD_PRELOAD=/usr/lib64/libtcmalloc.so
 export TCMALLOC_RELEASE_RATE=10
 export XRD_LOCALMETALINKFILE=1
-/usr/bin/xrootd -b -c $xcache_cfg -l /data/xrd/var/log/xrootd.log -k 7
+/usr/bin/xrootd -b -c $xcache_cfg -l /data/xrd/var/log/xrootd.log -k hup
 [ "$runcmsd" -eq 1 ] && /usr/bin/cmsd -b -c $xcache_cfg -l /data/xrd/var/log/cmsd.log -k 7