null-rsync - mirror a file tree to sparse files
null-rsync [options] rsync_source_url local_path
null-rsync [--exclude=pattern] [-q|--quiet] [-v|--verbose] rsync_source_url local_path
null-rsync [-h|--help]
null-rsync [--version]
null-rsync(1) mimics rsync(1), but can save massive amounts of time and diskspace if you need a copy of a file tree for testing purposes. If you don't care if the files contain zeroes, null-rsync(1) will create a filetree as a copy from a remote host, just like rsync does. But all files will contain only zeroes. Moreover, they will be created as sparse files that don't take disk space (besids metadata of the filesystem itself).
Technically, to get the file metadata over rsync, rsync's own itemized output is used, because it tells us all we need to know:
del. rw-r--r-- *deleting ultimate-edition-1.9-x64.iso 0 1970/01/01-01:00:00
recv rwxr-xr-x cd+++++++++ firefox/releases/3.0.15/ 4096 2009/10/26-19:23:12
recv rw-r--r-- >f+++++++++ firefox/releases/3.0.15/MD5SUMS 54256 2009/10/26-19:21:21
null-rsync(1) copies all permissions and timestamps where possible. An
exception are timestamps on symlinks, that can't be set by Python (its
os.utime() implementation always follows to the target). (It would work if
Python would export utimensat() with AT_SYMLINK_NOFOLLOW. See
utimensat(2).) But it doesn't really matter.
null-rsync(1) can be run again and again to synchronize the local tree with upstream changes. Just like you would do with rsync(1).
If the remote source contains world-writable directories, they are not made world-writable locally.
-v, --verbosePrint debug messages to stderr.
-q, --quietIf lock can't be acquired immediately, silently quit without error.
--versionShow program's version number and exit.
-h, --helpShow command synopsis and exit.
--exclude=patternExclude files matching pattern (which is passed through to rsync)
You can simply substitute a usual rsync(1) call with null-rsync(1).
null-rsync --exclude source rsync://mirrors.tds.net/debian/dists/jessie/main/ /tmp/sparse-debian-mirror
This program was written by Peter Pöml peter@poeml.de in 2009-2015.
rsync(1)