Both SCP and RSYNC use SSH to transfer files and directories.
While SCP simply uploads or downloads files and folders, RSYNC can synchronize the content of two folders by copying only what is new.
The basic syntax of both looks like this:
[scp/rsync] [OPTION] … [SRC] … [USER@]HOST:DEST [scp/rsync] [OPTION] … [USER@]HOST:SRC [DEST]
SCP
scp /home/user/file.zip [email protected]:/home/user/file.zip scp file.zip [email protected]:/home/user scp file.zip 200.100.50.3:/home/user scp file.zip [email protected]: scp file.zip 200.100.50.3: scp [email protected]:/home/user/file.zip /home/user/file.zip scp [email protected]:/home/user/file.zip /home/user scp [email protected]:/home/user/file.zip . scp 200.100.50.3:file.zip /home/user scp 200.100.50.3:file.zip .
The examples above show multiple ways to upload (1 to 5) and download (6 to 10) files.
The first example in each block (in bold) shows the complete syntax, unless you need to apply additional options.
By omitting the filename at the destination, it will be copied with the same name.
By omitting the full path on the source, it refers to the current directory.
By omitting the full path at the destination, it saves to the home directory of the user.
By omitting the username, it will use the same username as the one you are logged in with locally.
Use the option -r to copy directories recursively, -v (verbose) to print debugging messages, and -P (same as –progress) to see real-time progress.
RSYNC
The main feature of RSYNC is the ability to compare file dates and directory contents to determine what is new or missing on either side.
rsync -r /directory [email protected]:/directory rsync -r [email protected]:/directory /directory
The option -r (recursive) copies all content, while option -a (archive) compares both directories (local and remote) and only copies what is missing or has been updated.
Option -b (backup) will not overwrite the old file with the new version but instead makes a backup copy of the old one first (file.zip~). The option –delete removes files at the destination that were deleted from the source.
Using option -z (compress), traffic will be compressed, saving time on slow connections but increasing CPU usage on both ends. The option –dry-run simulates the operation and shows what would be done without actually performing any changes.
The option –exclude ‘dir1’ prevents RSYNC from comparing or copying a specific file or directory.
You can also try the option –backup-dir=$(date +%F) to see what it does.
BONUS
LSYNCD is a tool that runs as a service and periodically compares and syncs files (using RSYNC) based on a provided configuration.
sudo apt install lsyncd -y sudo mkdir /etc/lsyncd sudo nano /etc/lsyncd/lsyncd.conf.lua
Add the following content, customizing the parameters in bold:
settings {
logfile = "/var/log/lsyncd/lsyncd.log",
statusFile = "/var/log/lsyncd/lsyncd.status",
statusInterval = 20,
nodaemon = false
}
sync {
default.rsync,
source = "/path/",
target = "/path"
}
Note: the interval (20) is in seconds.
systemctl start lsyncd systemctl enable lsyncd systemctl status lsyncd
For troubleshooting:
tail -f /var/log/lsyncd/lsyncd.log tail -f /var/log/lsyncd/lsyncd.status
Backing up additional or newer files from source to destination.
rsync -rlptgo /source /destination