RSYNC is a fast, versatile, and powerful command utility used in Unix/Linux throught the secure shell (SSH) to synchronize files and directories from one location to another, while minimizing file data transfer using its delta-transfer algorithm. `-P` is one of the popular options used with RSYNC which influences how it operates.
The `-P` option in RSYNC is a combination of two other options: `—progress` and `—partial`. It is commonly used to display transfer progress and to keep partially transferred files.
1. `—progress` : This part of `-P` option displays the file transfer progress during the synchronization process. It provides a progress summary indicating the percentage of transfer completed, speed at which the transfer is occurring, and remaining time.
1. `—partial` : This part of `-P` option keeps the partially transferred files if the transfer process is interrupted. Normally, if a transfer process gets interrupted, RSYNC removes the file that was being transferred. But `—partial` ensures that the partially transferred file is not deleted. Instead, the next time you run RSYNC, it will continue from where it left off.
Here’s an example: Say, you want to synchronize a directory from one location to another, and you want to see the progress of the transfer and ensure that any interruptions don’t result in lost data. In such a case, you might use the following RSYNC command with the `-P` option:
`rsync -P source_directory/ destination_directory/`
This command will synchronize the source directory to the destination directory, providing updates on the progress of the transfer, and safeguarding against data loss in case of interruptions.
For more details and other options in RSYNC, please refer to its extensive man page which contains full details of its features and options (source: rsync man page) or online tutorials from reputable teaching sources such as Red Hat (source: https://www.redhat.com/sysadmin/rsync-tutorial). Middleware Inventory provides a really good comprehensive tutorial for first-time users with clear explanation of all options in RSYNC (source: https://www.middlewareinventory.com/blog/rsync-command-examples/).
In conclusion, `-P` option in RSYNC is a powerful option that provides real-time progress while synchronizing files and allows the process to resume in case of any interruption, thereby ensuring file integrity and efficient transfer.
