Prevent unfinished incremental backup file from being used

backup-tar/backup.sh

@@ -43,6 +43,7 @@ TIMESTAMP=$(date +"%Y-%m-%d")
 BACKUP_FILE=${TIMESTAMP}.${TYPE}.tar.xz
 INCFILE_TGT=stamps/${TIMESTAMP}.${TYPE}.snar
 INCFILE=${TIMESTAMP}.${TYPE}.snar
+INCFILE_TMP=${INCFILE_TMP}.tmp
 
 INC_FILTER="."
 if [[ "$TYPE" = "weekly" ]]; then
@@ -54,15 +55,16 @@ trap "rmdir lock" EXIT
 
 set -x
 
-[[ -f $INCFILE ]] && fail "ERROR: backup already in progress (incremental backup file exists)"
+[[ -f $INCFILE_TMP ]] && fail "ERROR: backup already in progress (incremental backup file exists)"
 if [[ "$TYPE" != "full" ]]; then
     LAST=$(ls *.snar | sort | grep $INC_FILTER | tail -n1)
     if [[ -f "$LAST" ]]; then
-        cp --reflink=auto $LAST $INCFILE
+        cp --reflink=auto $LAST $INCFILE_TMP
     fi
 fi
 
 ssh $TARGET "mkdir -p stamps"
-tar --create --xattrs --acls --listed-incremental=$INCFILE $SOURCES | \
+tar --create --xattrs --acls --listed-incremental=$INCFILE_TMP $SOURCES | \
     xz -T$COMPRESS_THRS -3 | ssh $TARGET "cat > $BACKUP_FILE"
-scp $INCFILE $TARGET:$INCFILE_TGT
+scp $INCFILE_TMP $TARGET:$INCFILE_TGT
+mv $INCFILE_TMP $INCFILE