auto backup local file in folder using crontab and rsync

it is really fast working at local hard disk. but the disadvantage is that it is not backuped. so a better way would be working at local hard disk that are automatically backed up as schedule.
two problems here.
1. how to make a schedule
2. how to sync with two folders.

slolution to problem 1:

using command

$ crontab

two useful parameters:

$ crontab -e

after executing this, a text editor pops out, which is the place one lodge a schedule, the format is like this (one can use # to comment out unnecessary schedules )

Code:

* * * * * /path/to/the/bash/script

the first star means minutes, it can be 0 to 59 or *. if it is star (*), it means every minute
the second star means hour, it can be 0 to 23 or *. if it is star (*), it means every hour
the third star means day of the month, it can be 0 to 31 or start*. if it is star (*), it means every day
the fourth star means month of the year, it can be 1 to 12. if it is star (*), it means every month
the fifth star means day of the week. if it is star (*), it means every day.

my final script after executing crontab -e is:
0 18 * * * /home/chenming/Hdrive/backup6.4

which means run backup6.4 at 18:00 of each day.

one needs to make sure that backup6.4 is a executable file (chmod +x backup6.4)

some other useful commands:

$ crontab -l

list schedules 

I usually use the following one to test:

schedule:

* * * * * /home/chenming/Hdrive/backup6.4

commands:

#!/bin/bash
echo $(date)>>/home/chenming/test

which writes date and time in one file per minute.




solution to problem 2:

use command rsync. put the following line in /home/chenming/Hdrive/backup6.4

rsync -a --progress --human-readable --states --update /path/to/folder/needs/to/be/synced --delete /path/to/folder/backup/file/stores/

here --progress shows the results (not useful as a schedule, though)
       --stats vobose mode
       --update skip files that are newer on the receiver (this is not useful if one doesn't change anything in receiver)
       --delete delete  extraneous files from dest dirs

Notes for systemd user:

you need to make sure that the service dcron is enabled:

 systemctl status dcron
systemctl is-enabled dcron

To enable it, you can do:

systemctl enable dcron