refactor(script): used fixed export location

- previous random name made full restore virtually impossible
- use one container directory to make full restore easy
- store each backup in timestamped subdirectory for easy
incremental restore

pilerBackup/pilerbackup.sh

@@ -421,7 +421,8 @@ printf "%s[%s] -- [INFO] %s%s%s imported --%s\n" \
 
 ## create tmp directory and change to it for export operations
 # create temporary directory to dump exported email from piler
-if ! exportDir=$( mktemp -d 2>>"$logFile" ); then
+tmpdir="/tmp/emailbackup/$( date +%F_%T )"
+if ! exportDir=$( mkdir -p "${tmpdir}" 2>>"$logFile" ); then
     exitError 111 "Could not create temporary directory for exported EML files"
 fi
 # grant pilerUser permission to write to temporary directory