Recipe 16.2. Using rsync for Local File Transfers and Synchronization
16.2.1 Problem
You need to keep
file trees synchronized on your workstation because your workstation
is a staging ground for web directories, image galleries, source code
trees, or other complex collections of files. So you use a working
directory for editing files, and then copy the finished files to a
separate upload directory. You would like something faster and more
intelligent than cp, because
cp takes a long time and you lose track of what
needs to be copied.
16.2.2 Solution
Use rsync to keep file trees synchronized.
rsync copies only changes, so it speeds up file
copying, and it tracks changes inside files and in file trees.
Be sure you have the latest version, to get all the bugfixes and
security patches. You definitely want 2.6 or later:
$ rsync —version
rsync version 2.6.2 protocol version 26
...
This command copies a directory of web files to a staging directory
that will later be uploaded to the web server:
$ rsync -av —stats /home/pearlbear/webs ~/web_upload
building file list ... done
...<all the files being copied fly by>...
Number of files: 254
Number of files transferred: 235
Total file size: 8923014 bytes
Total transferred file size: 8923014 bytes
Literal data: 8923014 bytes
Matched data: 0 bytes
File list size: 6490
Total bytes written: 8939848
Total bytes read: 3780
To verify the transfer, use:
$ ls ~/web_upload
webs
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There is a subtle gotcha here:
/home/pearlbear/images transfers the contents of
/images and the images directory itself. Adding
a trailing slash (/home/pearlbear/images/)
copies only the contents of the /images
directory, but not the directory itself. The trailing slash only
matters on the source directory; it makes no difference on the
destination directory.
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If more files are added to /home/pearlbear/webs,
or any existing files are changed, simply re-run the same command.
rsync will transfer only the changes.
You can specify more than one source directory to be copied:
$ rsync -av /home/pearlbear/webs /home/pearlbear/web_images ~/web_upload
You can also test your rsync command first with
the —dry-run option:
$ rsync -av —dry-run /home/pearlbear/webs /home/pearlbear/web_images ~/web_upload
16.2.3 Discussion
If any files are deleted from the source directory,
rsync will not delete
them from the destination directory unless you explicitly tell it to
with the —delete flag:
$ rsync -av —delete /home/pearlbear/webs ~/web_upload
The -av flags mean archive,
which retains file permissions and ownership, and
verbose output.
Be careful using the —delete flag; if you
accidentally delete from the rsync archive a
file that you wanted to keep, it's gone for good. Be
especially careful with your filepaths, because
—delete will happily erase an entire
directory or file tree.
rsync is a great tool for keeping local archives
synchronized. When you're authoring web pages,
writing code, assembling files to burn to CD, or managing any kind of
large collection of files, it's a real timesaver to
have rsync track and synchronize all the
changes.
Installation is simple—both RPMs and Debian packages are named
rsync, and you only need the single package. The
sources are statically linked, so there is no danger of dependency
problems, however you elect to install it.
16.2.4 See Also
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