Can Rsync be configured to verify the contents of the file before they are being synced. I have heard about checksum, but I came to know that checksum only does a sampling. I want to transfer a file only if it is contents are changed and not timestamp, is there a way to do it with any of the rsync modes.
In my scenario, say file sample.text will be created every week and I want to sync it with a remote server only if the contents of sample.text are changed, since it is created every week, the time stamp would obviously change. But I want the transfer only on a content change.
Yes:
$ man rsync | grep "\--checksum"
-c, --checksum skip based on checksum, not mod-time & size
Rsync is pretty complicated. I recommend cuddle time with the man page and experimentation with test data before using it for anything remotely important.
Most of the time, people use rsync -ac source dest.
$ man rsync | grep "\--archive"
-a, --archive archive mode; same as -rlptgoD (no -H)
And that -rlptgoD garbage means: recursive (r), copy symlinks as symlinks (l), preserve permissions (p), preserve times (t), preserve group (g), preserve owner (o), preserve device files (D, super-user only), preserve special files (also part of D).
The -c or --checksum is really what you are looking for (skip based on checksum, not mod-time & size). Your supposition that rsync only samples mtime and size is wrong.
See the --checksum option on the rsync man page.
Also, the --size-only option will be a faster choice if you know for sure that a change of contents also means a change of size.
Example:
#!/bin/bash
echo > diff.txt
rsync -rvcn --delete /source/ /destination/ > diff.txt
second_row=$(sed -n '2p' diff.txt)
if [ "$second_row" = "" ]; then
echo there was no change
else
echo there was change
fi
Related
I need to copy a file from multiple locations to the BACK UP directory by retaining its directory structure. For example, I have a file "a.txt" at the following locations /a/b/a.txt /a/c/a.txt a/d/a.txt a/e/a.txt, I now need to copy this file from multiple locations to the backup directory /tmp/backup. The end result should be:
when i list /tmp/backup/a --> it should contain /b/a.txt /c/a.txt /d/a.txt & /e/a.txt.
For this, I had used the command: echo /a/*/a.txt | xargs -I {} -n 1 sudo cp --parent -vp {} /tmp/backup. This is throwing the error "cp: cannot stat '/a/b/a.txt /a/c/a.txt a/d/a.txt a/e/a.txt': No such file or directory"
-I option is taking the complete input from echo instead of individual values (like -n 1 does). If someone can help debug this issue that would be very helpful instead of providing an alternative command.
Use rsync with the --relative (-R) option to keep (parts of) the source paths.
I've used a wildcard for the source to match your example command rather than the explicit list of directories mentioned in your question.
rsync -avR /a/*/a.txt /tmp/backup/
Do the backups need to be exactly the same as the originals? In most cases, I'd prefer a little compression. [tar](https://man7.org/linux/man-pages/man1/tar.1.html) does a great job of bundling things including the directory structure.
tar cvzf /path/to/backup/tarball.tgz /source/path/
tar can't update compressed archives, so you can skip the compression
tar uf /path/to/backup/tarball.tar /source/path/
This gives you versioning of a sort, as if only updates changed files, but keeps the before and after versions, both.
If you have time and cycles and still want the compression, you can decompress before and recompress after.
I'd like to copy a file to a directory without changing the modification timestamp of the directory on an ext4 filesytem. Well, many files and many directories in a script.
I've looked at rsync and cp options.
So to frame the question, how do I copy a file on an ext4 filesystem and preserve the timestamp on the destination directory?
There are many ways to copy files and preserve their attributes but they modify the parent directory timestamp. What's needed is the two step process of recording that timestamp and applying it after the copy. That was not addressed in the question referenced. Giving a file/directory the same modification date as another
One option is to save and restore the timestamp:
# Save current modification time
timestamp=$(stat -c #%Y mydir)
[.. copy/sync files ..]
# Restore that timestamp
touch -d "$timestamp" mydir
See this guid. If you want to preserve original timestamp use
$ touch -r <original_file> <new_file>.
This copy the attributes from another file. If you need to change specific attributes use following.
For Access time
$ touch -a --date="1988-02-15" file.txt
For Modify time:
$ touch -m --date="2020-01-20" file.txt
To see stat of a file or folder, Use stat <file>
$ cp --preserve=timestamps oldfile newfile
or
$ cp -p oldfile newfile would do that. Man pages clearly state that.
I am doing a clean up activity on files based on the time with which they create , however I also have to take a backup with scp without modifying the ctime or mtime of files
Later I will use find command to pick the qualified files with mtime in my shells script
find $V_Filepath -mmin +7200 -name "*.ack"
To keep the mtime unchanged scp -p option would help in terms of doing scp between two servers.
eg:
scp -pr myfile.* username#server://path/
Comparing the mtime (using stat command) before and after remains same. scp -p option preserves the mtime of the files
eg:
stat -c '%y' myfile.*
Modification time is the mtime, not ctime. scp -p already preserves mtime.
ctime is the inode change time, updated every time the file itself is touched in any way – renamed, moved, chmodded, etc.
Generally, there is no way to preserve it, as the OS does not provide any function for that, and even if it did, the very act of setting the ctime would be a change that would cause the ctime to be updated again.
Firstly I'd like to apologize if I duplicated a questions which already exists but it's too important to screw this.
I have two directories on my linux server:
- /tmp/tmp as source
- /var as destination
There are already like 500 txt files in /var directory and I'd like to move all my files from /tmp directory (about 200 files) to /var directory with replacing those ones which already exist with the same name but as well as not touching those ones which are not in /tmp.
Practical example:
/var files: a.txt , b.txt , c.txt , d.txt
/tmp files: a.txt , b.txt
Result: /var files: a.txt(from /tmp) , b.txt(from /tmp) , c.txt , d.txt
Not sure if mv is a proper method to do that, so thank you in advance guys! :)
This can be implemented through rsync
Refer rsync manual for more information.
Local: rsync [OPTION...] SRC... [DEST]
Access via remote shell:
Pull: rsync [OPTION...] [USER#]HOST:SRC... [DEST]
Push: rsync [OPTION...] SRC... [USER#]HOST:DEST
Access via rsync daemon:
Pull: rsync [OPTION...] [USER#]HOST::SRC... [DEST]
rsync [OPTION...] rsync://[USER#]HOST[:PORT]/SRC... [DEST]
Push: rsync [OPTION...] SRC... [USER#]HOST::DEST
rsync [OPTION...] SRC... rsync://[USER#]HOST[:PORT]/DEST
For your case,
rsync -avzh /tmp/ /var/
If you want to test it
rsync -avzh --dry-run /tmp/ /var/
-a, --archive archive mode;
-v, --verbose increase verbosity
-z, --compress compress file data during the transfer
-h, --human-readable output numbers in a human-readable format
Detailed commentary
-v, --verbose This option increases the amount of information you are given during the transfer. By default, rsync works silently. A single
-v will give you information about what files are being transferred and a brief summary at the end. Two -v options will give you
information on what files are being skipped and slightly more
information at the end. More than two -v options should only be used
if you are debugging rsync. Note that the names of the transferred
files that are output are done using a default --out-format of
lq%n%Lrq, which tells you just the name of the file and, if the item
is a link, where it points. At the single -v level of verbosity, this
does not mention when a file gets its attributes changed. If you ask
for an itemized list of changed attributes (either --itemize-changes
or adding lq%irq to the --out-format setting), the output (on the
client) increases to mention all items that are changed in any way.
See the --out-format option for more details.
-a, --archive This is equivalent to -rlptgoD. It is a quick way of saying you want recursion and want to preserve almost everything (with
-H being a notable omission). The only exception to the above equivalence is when --files-from is specified, in which case -r is not
implied. Note that -a does not preserve hardlinks, because finding
multiply-linked files is expensive. You must separately specify -H.
--no-OPTION You may turn off one or more implied options by prefixing the option name with lqno-rq. Not all options may be prefixed with a
lqno-rq: only options that are implied by other options (e.g. --no-D,
--no-perms) or have different defaults in various circumstances (e.g. --no-whole-file, --no-blocking-io, --no-dirs). You may specify either the short or the long option name after the lqno-rq prefix (e.g.
--no-R is the same as --no-relative). For example: if you want to use -a (--archive) but don't want
-o (--owner), instead of converting -a into -rlptgD, you could specify -a --no-o (or -a --no-owner). The order of the options is important: if you specify --no-r -a, the
-r option would end up being turned on, the opposite of -a --no-r. Note also that the side-effects of the --files-from option are NOT
positional, as it affects the default state of several options and
slightly changes the meaning of -a (see the --files-from option for
more details).
-z, --compress With this option, rsync compresses the file data as it is sent to the destination machine, which reduces the amount of data
being transmitted -- something that is useful over a slow connection.
Note that this option typically achieves better compression ratios
than can be achieved by using a compressing remote shell or a
compressing transport because it takes advantage of the implicit
information in the matching data blocks that are not explicitly sent
over the connection.
-h, --human-readable Output numbers in a more human-readable format. This makes big numbers output using larger units, with a K, M, or G
suffix. If this option was specified once, these units are K (1000), M
(1000*1000), and G (1000*1000*1000); if the option is repeated, the
units are powers of 1024 instead of 1000.
You cannot merge two directories using mv command simply. You can use either of the following ways:
1) You can use cp and rm commands to achieve your purpose.
$ cp -r /var /tmp
$ rm -rf /var
2) Using rsync, you can achieve that but rsync doesn't actyally "move" as per your question. It rather copies from one location to other(usually remote).
$ rsync -a -v /var /tmp
$ rm -r /var
I think this should serve the purpose. Cheers!
I just copied a ton of data from a machine running Windows 7 Ultimate to a server running Ubuntu Server LTS 10.04. I used the robocopy utility via PowerShell to accommplish this task, but I couldn't find any informaiton online regarding whether Robocopy verifies the copied file's integrity once it is copied to the server.
First of all, does anyone know if this is done inherently? There is no switch that explicitly allows you to add verification to a file transfer.
Second, if it doesn't or there is uncertainty about whether or not it does, what would be the simplest method to accomplish this for multiple directories with several files/sub-directories?
Thanks!
The easiest mechanism I know would rely on an md5sum and Unix-like find utility on your Windows machine.
You can generate a manifest file of filenames / md5sums:
find /source -type f -exec md5sum {} \; > MD5SUM
Copy the MD5SUM file to your Linux machine, and then run:
cd /path/to/destination
md5sum --quiet -c MD5SUM
You'll get a list of files that fail:
$ md5sum --quiet -c /tmp/MD5SUM
/etc/aliases: FAILED
md5sum: WARNING: 1 of 341 computed checksums did NOT match
Much easier method is to use unix uilities diff and rsync
With diff you can compare two file but you can compare also two directories. With diff I would recomend this command:
diff -r source/directory/ destination/directory
-r forces diff to analyse directorysor recursively
The second option is to use rsync which is ment to sync files or directories but with -n option you can use it also to analyes differencies between directories. rsync also works even when the files are not on the same host it means on one there can be remote host and you can acess it even with ssh. Pluss rsync is really flexible with its meny options avaialbe
rsync -avn --itemize-changes --progress --stats source/directory/ destination/directory/
-n option makes rsync do a "dry-run", meaning it makes no changes on the
-a otion includes in it "Recursive mode,symbolic links,file permissions, file timestamps, file owner parameter, file group paratmeter
-v increase verbosity
--itemize-changes output a change-summary for all updates
Here you can find even more ways how to compear directories:
https://askubuntu.com/questions/12473/file-and-directory-comparison-tool
On rsync wikipedia page you can find windows alternative programs for rsync