Rsync Directory

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Tutorial

Introduction

Installing Rsync. Rsync comes pre-installed in Ubuntu 20.04 LTS. However, if it is accidentally. Exclude a specific directory. Frist we remove destination directory if it exist by typing below.

Rsync, which stands for “remote sync”, is a remote and local file synchronization tool. It uses an algorithm that minimizes the amount of data copied by only moving the portions of files that have changed.

In this guide, we will cover the basic usage of this powerful utility.

What Is Rsync?

Rsync directory slash

Rsync is a very flexible network-enabled syncing tool. Due to its ubiquity on Linux and Unix-like systems and its popularity as a tool for system scripts, it is included on most Linux distributions by default.

Basic Syntax

The basic syntax of rsync is very straightforward, and operates in a way that is similar to ssh, scp, and cp.

We will create two test directories and some test files with the following commands:

We now have a directory called dir1 with 100 empty files in it.

We also have an empty directory called dir2.

To sync the contents of dir1 to dir2 on the same system, type:

The -r option means recursive, which is necessary for directory syncing.

We could also use the -a flag instead:

The -a option is a combination flag. It stands for “archive” and syncs recursively and preserves symbolic links, special and device files, modification times, group, owner, and permissions. It is more commonly used than -r and is usually what you want to use.

An Important Note

You may have noticed that there is a trailing slash (/) at the end of the first argument in the above commands:

This is necessary to mean “the contents of dir1”. The alternative, without the trailing slash, would place dir1, including the directory, within dir2. This would create a hierarchy that looks like:

Always double-check your arguments before executing an rsync command. Rsync provides a method for doing this by passing the -n or --dry-run options. The -v flag (for verbose) is also necessary to get the appropriate output:

Compare this output to the output we get when we remove the trailing slash:

You can see here that the directory itself is transferred.

How To Use Rsync to Sync with a Remote System

Syncing to a remote system is trivial if you have SSH access to the remote machine and rsync installed on both sides. Once you have SSH access verified between the two machines, you can sync the dir1 folder from earlier to a remote computer by using this syntax (note that we want to transfer the actual directory in this case, so we omit the trailing slash):

This is called a “push” operation because it pushes a directory from the local system to a remote system. The opposite operation is “pull”. It is used to sync a remote directory to the local system. If the dir1 were on the remote system instead of our local system, the syntax would be:

Like cp and similar tools, the source is always the first argument, and the destination is always the second.

Useful Options for Rsync

Rsync provides many options for altering the default behavior of the utility. We have already discussed some of the more necessary flags.

If you are transferring files that have not already been compressed, like text files, you can reduce the network transfer by adding compression with the -z option:

The -P flag is very helpful. It combines the flags --progress and --partial. The first of these gives you a progress bar for the transfers and the second allows you to resume interrupted transfers:

If we run the command again, we will get a shorter output, because no changes have been made. This illustrates rsync’s ability to use modification times to determine if changes have been made.

Rsync Directory

We can update the modification time on some of the files and see that rsync intelligently re-copies only the changed files:

In order to keep two directories truly in sync, it is necessary to delete files from the destination directory if they are removed from the source. By default, rsync does not delete anything from the destination directory.

Sync

We can change this behavior with the --delete option. Before using this option, use the --dry-run option and do testing to prevent data loss:

If you wish to exclude certain files or directories located inside a directory you are syncing, you can do so by specifying them in a comma-separated list following the --exclude= option:

If we have specified a pattern to exclude, we can override that exclusion for files that match a different pattern by using the --include= option.

Finally, rsync’s --backup option can be used to store backups of important files. It is used in conjunction with the --backup-dir option, which specifies the directory where the backup files should be stored.

Conclusion

Rsync can simplify file transfers over networked connections and add robustness to local directory syncing. The flexibility of rsync makes it a good option for many different file-level operations.

A mastery of rsync allows you to design complex backup operations and obtain fine-grained control over what is transferred and how.

rsync is an open source utility that provides fast incremental file transfer.

Installation

Install the rsync package.

rsync must be installed on both the source and the destination machine.

Front-ends

  • Grsync — GTK front-end.
http://www.opbyte.it/grsync/ grsync
  • gutback — rsync wrapper written in Shell.
https://github.com/gutenye/gutbackup gutbackupAUR
  • JotaSync — Java Swing GUI for rsync with integrated scheduler.
https://trixon.se/projects/jotasync/ jotasyncAUR
  • luckyBackup — Qt front-end written in C++.
http://luckybackup.sourceforge.net/index.html luckybackupAUR

Other tools using rsync are rdiff-backup and osyncAUR.

As cp/mv alternative

rsync can be used as an advanced alternative for the cp or mv command, especially for copying larger files:

The -P option is the same as --partial --progress, which keeps partially transferred files and shows a progress bar during transfer.

You may want to use the -r/--recursive option to recurse into directories.

Files can be copied locally as with cp, but the motivating purpose of rsync is to copy files remotely, i.e. between two different hosts. Remote locations can be specified with a host-colon syntax:

or

Network file transfers use the SSH protocol by default and host can be a real hostname or a predefined profile/alias from .ssh/config.

Whether transferring files locally or remotely, rsync first creates a file-list containing information (by default, it is the file size and last modification timestamp) which will then be used to determine if a file needs to be constructed. For each file to be constructed, a weak and strong checksum is found for all blocks such that each block is of length S bytes, non-overlapping, and has an offset which is divisible by S. Using this information a large file can be constructed using rsync without having to transfer the entire file. For a more detailed practical explanation and detailed mathematical explanation refer to how rsync works and the rsync algorithm, respectively.

To use sane defaults quickly, you could use some aliases:

Note: The use of the term checksum is not interchangeable with the behavior of the --checksum option. The --checksum option affects the file skip heuristic used prior to any file being transferred. Independent of --checksum, a checksum is always used for the block-based file construction which is how rsync transfers a file.

Trailing slash caveat

Arch by default uses GNU cp (part of GNU coreutils). However, rsync follows the convention of BSD cp, which gives special treatment to source directories with a trailing slash '/'. Although

creates a directory 'destination/source' with the contents of 'source', the command

copies all of the files in 'source/' directly into 'destination', with no intervening subdirectory - just as if you had invoked it as

This behavior is different from that of GNU cp, which treats 'source' and 'source/' identically (but not 'source/.'). Also, some shells automatically append the trailing slash when tab-completing directory names. Because of these factors, there can be a tendency among new or occasional rsync users to forget about rsync's different behavior, and inadvertently create a mess or even overwrite important files by leaving the trailing slash on the command line.

Thus it can be prudent to use a wrapper script to automatically remove trailing slashes before invoking rsync:

This script can be put somewhere in the path, and aliased to rsync in the shell init file.

As a backup utility

The rsync protocol can easily be used for backups, only transferring files that have changed since the last backup. This section describes a very simple scheduled backup script using rsync, typically used for copying to removable media.

Automated backup

For the sake of this example, the script is created in the /etc/cron.daily directory, and will be run on a daily basis if a cron daemon is installed and properly configured. Configuring and using cron is outside the scope of this article.

First, create a script containing the appropriate command options:

-a
indicates that files should be archived, meaning that most of their characteristics are preserved (but not ACLs, hard links or extended attributes such as capabilities)
--delete
means files deleted on the source are to be deleted on the backup as well

Here, /path/to/backup should be changed to what needs to be backed-up (e.g. /home) and /location/of/backup is where the backup should be saved (e.g. /media/disk).

Finally, the script must be executable:

Automated backup with SSH

If backing-up to a remote host using SSH, use this script instead:

Rsync
-e ssh
tells rsync to use SSH
remoteuser
is the user on the host remotehost
-a
groups all these options -rlptgoD (recursive, links, perms, times, group, owner, devices)
Note: Rsync will try to modify any previously backed up files on the target machine to match their current state at the source machine, with each incremental backup. This means that when backing up files that are owned by root over SSH (and when preserving permissions and ownerships such as with the -a option), root access to the target machine is needed. The preferred way to achieve this for automation is to set up the SSH daemon to allow root to login using a public key without password and run the rsync command as root.

Automated backup with NetworkManager

This script starts a backup when network connection is established.

First, create a script containing the appropriate command options:

-a
group all this options -rlptgoD recursive, links, perms, times, group, owner, devices
--files-from
read the relative path of /path/to/backup from this file
--bwlimit
limit I/O bandwidth; KBytes per second

The script must be owned by root (see NetworkManager#Network services with NetworkManager dispatcher for details).

Automated backup with systemd and inotify

Note:
  • Due to the limitations of inotify and systemd (see this question and answer), recursive filesystem monitoring is not possible. Although you can watch a directory and its contents, it will not recurse into subdirectories and watch the contents of them; you must explicitly specify every directory to watch, even if that directory is a child of an already watched directory.
  • This setup is based on a systemd/User instance.

Instead of running time interval backups with time based schedules, such as those implemented in cron, it is possible to run a backup every time one of the files you are backing up changes. systemd.path units use inotify to monitor the filesystem, and can be used in conjunction with systemd.service files to start any process (in this case your rsync backup) based on a filesystem event.

First, create the systemd.path file that will monitor the files you are backing up:

Then create a systemd.service file that will be activated when it detects a change. By default a service file of the same name as the path unit (in this case backup.path) will be activated, except with the .service extension instead of .path (in this case backup.service).

Note: If you need to run multiple rsync commands, use Type=oneshot. This allows you to specify multiple ExecStart= parameters, one for each rsync command, that will be executed. Alternatively, you can simply write a script to perform all of your backups, just like cron scripts.

Rsync Directory Rename

Now all you have to do is start/enable backup.path like a normal systemd service and it will start monitoring file changes and automatically start backup.service.

Differential backup on a week

This is a useful option of rsync, resulting in a full backup (on each run) and keeping a differential backup copy of changed files only in a separate directory for each day of a week.

First, create a script containing the appropriate command options:

--inplace
implies --partial update destination files in-place

Snapshot backup

The same idea can be used to maintain a tree of snapshots of your files. In other words, a directory with date-ordered copies of the files. The copies are made using hardlinks, which means that only files that did change will occupy space. Generally speaking, this is the idea behind Apple's TimeMachine.

This basic script is easy to implement and creates quick incremental snapshots using the --link-dest option to hardlink unchanged files:

There must be a symlink to a full backup already in existence as a target for --link-dest. If the most recent snapshot is deleted, the symlink will need to be recreated to point to the most recent snapshot. If --link-dest does not find a working symlink, rsync will proceed to copy all source files instead of only the changes.

A more sophisticated version keeps an up-to-date full backup $SNAP/latest and in case a certain number of files has changed since the last full backup, it creates a snapshot $SNAP/$DATETAG of the current full-backup utilizing cp -al to hardlink unchanged files:

To make things really, really simple this script can be run from a systemd/Timers unit.

Full system backup

This section is about using rsync to transfer a copy of the entire / tree, excluding a few selected directories. This approach is considered to be better than disk cloning with dd since it allows for a different size, partition table and filesystem to be used, and better than copying with cp -a as well, because it allows greater control over file permissions, attributes, Access Control Lists and extended attributes.

rsync will work even while the system is running, but files changed during the transfer may or may not be transferred, which can cause undefined behavior of some programs using the transferred files.

Rsync

This approach works well for migrating an existing installation to a new hard drive or SSD.

Run the following command as root to make sure that rsync can access all system files and preserve the ownership:

Wget Directory Tree

By using the -aAX set of options, the files are transferred in archive mode which ensures that symbolic links, devices, permissions, ownerships, modification times, ACLs, and extended attributes are preserved, assuming that the target file system supports the feature. The option -H preserves hard links, but uses more memory.

The --exclude option causes files that match the given patterns to be excluded. The directories /dev, /proc, /sys, /tmp, and /run are included in the above command, but the contents of those directories are excluded. This is because they are populated on boot, but the directories themselves are not created. /lost+found is filesystem-specific. The command above depends on brace expansion available in both the bash and zsh shells. When using a different shell, --exclude patterns should be repeated manually. Quoting the exclude patterns will avoid expansion by the shell, which is necessary, for example, when backing up over SSH. Ending the excluded paths with * ensures that the directories themselves are created if they do not already exist.

Note:
  • If you plan on backing up your system somewhere other than /mnt or /media, do not forget to add it to the list of exclude patterns to avoid an infinite loop.
  • If there are any bind mounts in the system, they should be excluded as well so that the bind mounted contents is copied only once.
  • If you use a swap file, make sure to exclude it as well.
  • Consider if you want to backup the /home/ directory. If it contains your data it might be considerably larger than the system. Otherwise consider excluding unimportant sub-directories such as /home/*/.thumbnails/*, /home/*/.cache/mozilla/*, /home/*/.cache/chromium/*, and /home/*/.local/share/Trash/*, depending on software installed on the system.
  • If GVFS is installed, /home/*/.gvfs must be excluded to prevent rsync errors.
  • If Dhcpcd ≥ 9.0.0 is installed, exclude the /var/lib/dhcpcd/* directory as it mounts several system directories as sub-directories there.

You may want to include additional rsync options, or remove some, such as the following. See rsync(1) for the full list.

  • If you run on a system with very low memory, consider removing -H option; however, it should be no problem on most modern machines. There can be many hard links on the file system depending on the software used (e.g. if you are using Flatpak). Many hard links reside under the /usr/ directory.
  • You may want to add rsync's --delete option if you are running this multiple times to the same backup directory. In this case make sure that the source path does not end with /*, or this option will only have effect on the files inside the subdirectories of the source directory, but it will have no effect on the files residing directly inside the source directory.
  • If you use any sparse files, such as virtual disks, Docker images and similar, you should add the -S option.
  • The --numeric-ids option will disable mapping of user and group names; instead, numeric group and user IDs will be transfered. This is useful when backing up over SSH or when using a live system to backup different system disk.
  • Choosing --info=progress2 option instead of -v will show the overall progress info and transfer speed instead of the list of files being transferred.
  • To avoid crossing a filesystem boundary when recursing, add the option -x/--one-file-system. This will prevent backing up any mount point in the hierarchy.

Restore a backup

If you wish to restore a backup, use the same rsync command that was executed but with the source and destination reversed.

File system cloning

rsync provides a way to do a copy of all data in a file system while preserving as much information as possible, including the file system metadata. It is a procedure of data cloning on a file system level where source and destination file systems do not need to be of the same type. It can be used for backing up, file system migration or data recovery.

rsync's archive mode comes close to being fit for the job, but it does not back up the special file system metadata such as access control lists, extended attributes or sparse file properties. For successful cloning at the file system level, some additional options need to be provided:

And their meaning is (from the manpage):

Additionally, use -x if you have other filesystems mounted under the tree that you want to exclude from the copy.Produced copy can be simply reread and checked (for example after a data recovery attempt) at the file system level with diff's recursive option:

It is possible to do a successful file system migration by using rsync as described in this article and updating the fstab and bootloader as described in Migrate installation to new hardware. This essentially provides a way to convert any root file system to another one.

rsync daemon

rsync can be run as daemon on a server listening on port 873.

Edit the template /etc/rsyncd.conf, configure a share and start the rsyncd.service.

Note: As of rsync 3.2.0-1 the package adopted the upstream systemd unit files rsyncd.service and [email protected]. The change for ProtectHome has been commented, the security feature ProtectSystem=full under the [Service] section is still active. This makes the /boot/, /etc/ and /usr/ directories read-only. If you need rsyncd write system directories you can edit the unit and set ProtectSystem=off in the [Service] section of the overriding snippet.

Usage from client, e.g. list server content:

transfer file from client to server:

Consider iptables to open port 873 and user authentication.

Note: All transferred data including user authentication are not encrypted.

Wget Directory Download

Example configuration

Sharing from a list of files

Inside the file list, all the intermediary paths are necessary, except when the *** wildcard is used:

Rsync Directory Structure

See also

Rsync Directory Sync

  • More usage examples can be searched in the Community Contributions and General Programming forums
  • Howto – local and remote snapshot backup using rsync with hard links Includes file deduplication with hard-links, MD5 integrity signature, 'chattr' protection, filter rules, disk quota, retention policy with exponential distribution (backups rotation while saving more recent backups than older)

Rsync Directory Structure

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