Understanding and Utilizing the `rsync` Command in Linux
What Does Synchronizing Files Mean?
Synchronizing files, in the context of computing, refers to the process of ensuring that two or more locations contain an identical set of files and folders.
This process is crucial for data backup, replication for redundancy, or simply for keeping a consistent set of files across multiple devices or locations. The synchronization is not just about copying files, but also about doing it efficiently, transferring only the changes made rather than the entire files afresh.
The rsync Command
rsync (Remote Synchronization) is a versatile file-copying tool in Linux that
synchronizes files and directories from one location to another while minimizing
data transfer by using delta encoding when appropriate. It's commonly used for
backups and mirroring or just copying files with various conditions and
filtering.
Syntax of the rsync Command
The basic syntax for the rsync command is:
rsync [options] source destination
[options]: These are the flags that control the behavior ofrsync.source: The path to the source file(s) or directory.destination: The path where the files will be copied to.
Creating Example Files for Synchronization
Before we proceed with examples, let's create some files and directories that we
will use with rsync:
mkdir ~/rsync-source
mkdir ~/rsync-destination
echo "This is a test file." > ~/rsync-source/testfile1.txt
echo "This is another test file." > ~/rsync-source/testfile2.txt
Now we have a directory ~/rsync-source with two test files that we'll sync
to ~/rsync-destination.
Examples of Using the rsync Command
Basic File Synchronization
To synchronize all files from the source to the destination directory, use:
rsync -av ~/rsync-source/ ~/rsync-destination
This command syncs the contents of rsync-source to rsync-destination, -a
stands for 'archive' mode, which ensures permissions, timestamps, and other file
attributes are preserved, and -v enables verbose mode.
Dry Run
Before actually performing the sync, you can perform a dry run to see what changes would be made:
rsync -avn ~/rsync-source/ ~/rsync-destination
The -n option tells rsync to perform a trial run that makes no changes.
Synchronizing Over SSH
For syncing files to a remote server securely over SSH:
rsync -avz -e ssh ~/rsync-source/ user@remotehost:/path/to/destination
Here, -z enables compression during transfer, and -e ssh specifies using SSH
for the data transfer.
Excluding Files
If you want to exclude files from being synchronized:
rsync -av --exclude 'testfile2.txt' ~/rsync-source/ ~/rsync-destination
This command will sync all files except testfile2.txt.
Table of rsync Command Options
| Option | Shorthand | Description |
|---|---|---|
--archive | -a | Archive mode; equals -rlptgoD (no -H,-A,-X) |
--verbose | -v | Verbose mode; increases the amount of information shown |
--compress | -z | Compress file data during the transfer |
--dry-run | -n | Perform a trial run with no changes made |
--exclude | Exclude files matching pattern | |
--delete | Delete extraneous files from destination dirs | |
--progress | Show progress during transfer | |
--rsh=COMMAND | -e | Specify the remote shell to use |
--recursive | -r | Recurse into directories |
--times | -t | Preserve modification times |
--links | -l | Copy symlinks as symlinks |
--perms | -p | Preserve permissions |
--owner | -o | Preserve owner (super-user only) |
--group | -g | Preserve group |
--devices | -D | Preserve device files (super-user only) |
--specials | Preserve special files |
With these examples and the table of options, you can use rsync to efficiently
sync files between directories and even across different machines. `rsyncs
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