+ Cache="${Dir}/${CacheDir}/${CacheArchive}/"
+ Back="${Dir}/${CacheDir}/${CacheBackup}/"
+ BackX="${Back}${CacheArchive}/"
+ for x in $(seq 0 1 $((${BackupLevel}-1))); do
+ eval "Back${x}=${Back}${x}/"
+ done
+
+ # backup after n-days if archive contents changed.
+ # (This uses hardlink to save disk space)
+ BACKUP_ARCHIVE_STAMP=/var/lib/apt/periodic/backup-archive-stamp
+ if check_stamp $BACKUP_ARCHIVE_STAMP $BackupArchiveInterval; then
+ if [ $({(cd $Cache 2>/dev/null; find . -name "*.deb"); (cd $Back0 2>/dev/null;find . -name "*.deb") ;}| sort|uniq -u|wc -l) -ne 0 ]; then
+ mkdir -p $Back
+ rm -rf $Back$((${BackupLevel}-1))
+ for y in $(seq $((${BackupLevel}-1)) -1 1); do
+ eval BackY=${Back}$y
+ eval BackZ=${Back}$(($y-1))
+ if [ -e $BackZ ]; then
+ mv -f $BackZ $BackY ;
+ fi
+ done
+ cp -la $Cache $Back ; mv -f $BackX $Back0
+ update_stamp $BACKUP_ARCHIVE_STAMP
+ debug_echo "backup with hardlinks. (success)"
+ else
+ debug_echo "skip backup since same content."
+ fi
+ else
+ debug_echo "skip backup since too new."
+ fi
+}
+
+# sleep for a random interval of time (default 30min)
+# (some code taken from cron-apt, thanks)
+random_sleep()
+{
+ RandomSleep=1800
+ eval $(apt-config shell RandomSleep APT::Periodic::RandomSleep)
+ if [ $RandomSleep -eq 0 ]; then
+ return
+ fi
+ if [ -z "$RANDOM" ] ; then
+ # A fix for shells that do not have this bash feature.
+ RANDOM=$(dd if=/dev/urandom count=1 2> /dev/null | cksum | cut -c"1-5")
+ fi
+ TIME=$(($RANDOM % $RandomSleep))
+ debug_echo "sleeping for $TIME seconds"
+ sleep $TIME
+}
+
+
+debug_echo()
+{
+ # Display message if $VERBOSE >= 1
+ if [ "$VERBOSE" -ge 1 ]; then
+ echo $1 1>&2
+ fi
+}
+
+# ------------------------ main ----------------------------
+
+# check apt-config exstance
+if ! which apt-config >/dev/null ; then
+ exit 0
+fi
+
+# check if the user really wants to do something
+AutoAptEnable=1 # default is yes
+eval $(apt-config shell AutoAptEnable APT::Periodic::Enable)
+
+if [ $AutoAptEnable -eq 0 ]; then
+ exit 0
+fi
+
+# Set VERBOSE mode from apt-config (or inherit from environment)
+VERBOSE=0
+eval $(apt-config shell VERBOSE APT::Periodic::Verbose)
+debug_echo "verbose level $VERBOSE"
+if [ "$VERBOSE" -le 2 ]; then
+ # quiet for 0,1,2
+ XSTDOUT=">/dev/null"
+ XSTDERR="2>/dev/null"
+ XAPTOPT="-qq"
+ XUUPOPT=""
+else
+ XSTDOUT=""
+ XSTDERR=""
+ XAPTOPT=""
+ XUUPOPT="-d"
+fi
+if [ "$VERBOSE" -ge 3 ]; then
+ # trace output
+ set -x
+fi