rsync in linux

What is rsync ?
-> According to wikipedia,
rsync is a utility for efficiently transferring and synchronizing files between a computer and an external hard drive and across networked computers by comparing the modification times and sizes of files. It is commonly found on Unix-like operating systems.

Basically it is a tool for sync to directory. Directories can be remote and local.
You can read more about it here.  https://www.geeksforgeeks.org/rsync-command-in-linux-with-examples/

Please note the following behavior of rsync:

• Files that do not exist on the remote-host are copied.
• Files that have been updated will be synced, rsync will copy only the changed parts of files to the remote host.
• File that is exactly the same are not copied to the remote host at all.

Now, 

To sync a folder  locally use command

$ rsync -avh source destination 

Here  -avh is flag where a is for archived, v for verbose, h for human-readable format.


To sync a folder on a remote 

$ rsync -avhze ssh source user@remote-host:destination 

To show progress of transfer 
we can use --progress option.

$ rsync -avhze --progress ssh source user@remote-host:destination 

To delete files which are not in source
we can use --delete option

$ rsync -avh --delete source destination 

Performing a dry run
A dry run is a trial run. By using this we can get to know what happens if we run that command. Dry run doesn't make change to destination.

$ rsync -avh --delete --dry-run source destination