Rsync example....

rsync -abviuzP src/ dest/

• -i turns on the itemized format, which shows more information than the default format
• -b makes rsync backup files that exist in both folders, appending ~ to the old file. You can control this suffix with --suffix .suf
• -u makes rsync transfer skip files which are newer in dest than in src
• -z turns on compression, which is useful when transferring easily-compressible files over slow links
• -P turns on --partial and --progress
• --partial makes rsync keep partially transferred files if the transfer is interrupted
• --progress shows a progress bar for each transfer, useful if you transfer big files

Someone suggest to use:    rsync -abuP

rsync synchronizes in one direction from source to destination. Therefore the following statement

rsync -avh --progress Source Destination

syncs everything from Source to Destination. The merged folder resides in Destination.

-a means "archive" and copies everything recursively from source to destination preserving nearly everything.

-v gives more output ("verbose").

-h for human readable.

--progress to show how much work is done.

If you want only update the destination folder with newer files from source folder:

rsync -avhu --progress source destination