Home » scp and compress at the same time, no intermediate save

scp and compress at the same time, no intermediate save

Solutons:


There are many ways to do what you want. The simplest is to use a pìpe:

tar zcvf -  MyBackups | ssh user@server "cat > /path/to/backup/foo.tgz"

Here, the compression is being handled by tar which calls gzip (z flag). You can also use compress (Z) and bzip (j). For 7z, do this:

tar cf - MyBackups | 7za a -si -mx=9 -ms=on MyBackups.tar.7z | 
   ssh user@server "cat > /path/to/backup/foo.7z"

The best way, however, is probably rsync.

   Rsync is a fast and extraordinarily versatile  file  copying  tool.   It  can  copy
   locally, to/from another host over any remote shell, or to/from a remote rsync dae‐
   mon.  It offers a large number of options that control every aspect of its behavior
   and  permit  very  flexible  specification of the set of files to be copied.  It is
   famous for its delta-transfer algorithm, which reduces the amount of data sent over
   the network by sending only the differences between the source files and the exist‐
   ing files in the destination.  Rsync is widely used for backups and  mirroring  and
   as an improved copy command for everyday use.

rsync has way too many options. It really is worth reading through them but they are scary at first sight. The ones you care about in this context though are:

    -z, --compress              compress file data during the transfer
        --compress-level=NUM    explicitly set compression level

   -z, --compress
          With this option, rsync compresses the file data as it is sent to the desti‐
          nation 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.

So, in your case, you would want something like this:

rsync -z MyBackups user@server:/path/to/backup/

The files would be compressed while in transit and arrive decompressed at the destination.


Some more choices:

  • scp itself can compress the data

     -C      Compression enable.  Passes the -C flag to ssh(1) to
             enable compression.
    
    $ scp -C source user@server:/path/to/backup
    
  • There may be a way to get rsync and 7za to play nice but there is no point in doing so. The benefit of rsync is that it will only copy the bits that have changed between the local and remote files. However, a small local change can result in a very different compressed file so there is no point in using rsync for this. It just complicates matters with no benefit. Just use direct ssh as shown above. If you really want to do this, you can try by giving a subshell as an argument to rsync. On my system, I could not get this to work with 7za because it does not allow you to write compressed data to a terminal. Perhaps your implementation is different. Try something like (this does not work for me):

    rsync $(tar cf - MyBackups | 7za a -an -txz -si -so) 
      user@server:/path/to/backup
    
  • Another point is that 7z should not be used for backups on Linux. As stated on the 7z man page:

    DO NOT USE the 7-zip format for backup purpose on Linux/Unix
    because :
    – 7-zip does not store the owner/group of the file.

I think this command will do the trick

ssh user@host "cd /path/to/data/;tar zc directory_name" | tar zx 

Now, first of all you have to execute this command from the target host. And details to be explained:

  1. ssh user@host will open connection to host machine, from where the data is to be transfered.
  2. cd /path/to/data will take to the directory where required data is stored
  3. tar zc * will initiate compression and put it to the STDOUT
  4. Now pipe(|) will pipeline the STDOUT of the source to the STDIN of the destination where “tar zx ” is running and continuously decompression data stream coming from source.

As you can see this command compresses on-the-fly and saves bandwidth.
You can use other compressions as well for better results, but remember, compression and decompression needs CPU cycles.

Reference

Small improvement for the dkbhadeshiya’s answer: you don’t have to do cd dir, just specify working directory to the tar instead:

ssh user@host "tar -C /path/to/data/ -zc directory_name" | tar zx 

You can also upload directory the same way:

tar zc directory_name/ | ssh user@host "tar zx -C /new/path/to/data/"

Related Solutions

Joining bash arguments into single string with spaces

[*] I believe that this does what you want. It will put all the arguments in one string, separated by spaces, with single quotes around all: str="'$*'" $* produces all the scripts arguments separated by the first character of $IFS which, by default, is a space....

AddTransient, AddScoped and AddSingleton Services Differences

TL;DR Transient objects are always different; a new instance is provided to every controller and every service. Scoped objects are the same within a request, but different across different requests. Singleton objects are the same for every object and every...

How to download package not install it with apt-get command?

Use --download-only: sudo apt-get install --download-only pppoe This will download pppoe and any dependencies you need, and place them in /var/cache/apt/archives. That way a subsequent apt-get install pppoe will be able to complete without any extra downloads....

What defines the maximum size for a command single argument?

Answers Definitely not a bug. The parameter which defines the maximum size for one argument is MAX_ARG_STRLEN. There is no documentation for this parameter other than the comments in binfmts.h: /* * These are the maximum length and maximum number of strings...

Bulk rename, change prefix

I'd say the simplest it to just use the rename command which is common on many Linux distributions. There are two common versions of this command so check its man page to find which one you have: ## rename from Perl (common in Debian systems -- Ubuntu, Mint,...

Output from ls has newlines but displays on a single line. Why?

When you pipe the output, ls acts differently. This fact is hidden away in the info documentation: If standard output is a terminal, the output is in columns (sorted vertically) and control characters are output as question marks; otherwise, the output is...

mv: Move file only if destination does not exist

mv -vn file1 file2. This command will do what you want. You can skip -v if you want. -v makes it verbose - mv will tell you that it moved file if it moves it(useful, since there is possibility that file will not be moved) -n moves only if file2 does not exist....

Is it possible to store and query JSON in SQLite?

SQLite 3.9 introduced a new extension (JSON1) that allows you to easily work with JSON data . Also, it introduced support for indexes on expressions, which (in my understanding) should allow you to define indexes on your JSON data as well. PostgreSQL has some...

Combining tail && journalctl

You could use: journalctl -u service-name -f -f, --follow Show only the most recent journal entries, and continuously print new entries as they are appended to the journal. Here I've added "service-name" to distinguish this answer from others; you substitute...

how can shellshock be exploited over SSH?

One example where this can be exploited is on servers with an authorized_keys forced command. When adding an entry to ~/.ssh/authorized_keys, you can prefix the line with command="foo" to force foo to be run any time that ssh public key is used. With this...

Why doesn’t the tilde (~) expand inside double quotes?

The reason, because inside double quotes, tilde ~ has no special meaning, it's treated as literal. POSIX defines Double-Quotes as: Enclosing characters in double-quotes ( "" ) shall preserve the literal value of all characters within the double-quotes, with the...

What is GNU Info for?

GNU Info was designed to offer documentation that was comprehensive, hyperlinked, and possible to output to multiple formats. Man pages were available, and they were great at providing printed output. However, they were designed such that each man page had a...

Set systemd service to execute after fstab mount

a CIFS network location is mounted via /etc/fstab to /mnt/ on boot-up. No, it is not. Get this right, and the rest falls into place naturally. The mount is handled by a (generated) systemd mount unit that will be named something like mnt-wibble.mount. You can...

Merge two video clips into one, placing them next to each other

To be honest, using the accepted answer resulted in a lot of dropped frames for me. However, using the hstack filter_complex produced perfectly fluid output: ffmpeg -i left.mp4 -i right.mp4 -filter_complex hstack output.mp4 ffmpeg -i input1.mp4 -i input2.mp4...

How portable are /dev/stdin, /dev/stdout and /dev/stderr?

It's been available on Linux back into its prehistory. It is not POSIX, although many actual shells (including AT&T ksh and bash) will simulate it if it's not present in the OS; note that this simulation only works at the shell level (i.e. redirection or...

How can I increase the number of inodes in an ext4 filesystem?

It seems that you have a lot more files than normal expectation. I don't know whether there is a solution to change the inode table size dynamically. I'm afraid that you need to back-up your data, and create new filesystem, and restore your data. To create new...

Why doesn’t cp have a progress bar like wget?

The tradition in unix tools is to display messages only if something goes wrong. I think this is both for design and practical reasons. The design is intended to make it obvious when something goes wrong: you get an error message, and it's not drowned in...