How To Use tar Command Through Network Over SSH Session

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How do I use tar command over secure ssh session running on Linux or Unix-like system?

The GNU version of the tar archiving utility (and other old version of tar) can be use through network over ssh session. Do not use telnet command, it is insecure. You can use Unix/Linux pipes to create archives.

Let us see some examples of how to use the tar command over ssh securely to create archives on Linux or Unix-like system.
Tar over ssh on Linux or Unix

Syntax

The syntax is as follows to ssh into box and run the tar command:
ssh [email protected] tar czf - /dir1/ > /destination/file.tar.g
OR
ssh [email protected] 'cd /dir1/ && tar -cf - file | gzip -9' >file.tar.gz
The following command backups /wwwdata directory to dumpserver.nixcraft.in (IP 192.168.1.201) host over ssh session.
# tar zcvf - /wwwdata | ssh [email protected] "cat > /backup/wwwdata.tar.gz"OR# tar zcvf - /wwwdata | ssh [email protected] "cat > /backup/wwwdata.tar.gz"
Sample outputs:

tar: Removing leading `/' from member names
/wwwdata/
/wwwdata/n/nixcraft.in/
/wwwdata/c/cyberciti.biz/
....
..
...
Password:

The default first SCSI tape drive under Linux is /dev/st0. You can read more about tape drives naming convention used under Linux here. You can also use dd command for clarity purpose:
# tar cvzf - /wwwdata | ssh [email protected] "dd of=/backup/wwwdata.tar.gz"
It is also possible to dump backup to remote tape device:
# tar cvzf - /wwwdata | ssh [email protected] "cat > /dev/nst0"
OR you can use mt to rewind tape and then dump it using cat command:
# tar cvzf - /wwwdata | ssh [email protected] $(mt -f /dev/nst0 rewind; cat > /dev/nst0)$
You can restore tar backup over ssh session: # cd /
# ssh [email protected] "cat /backup/wwwdata.tar.gz" | tar zxvf -
If you wish to use above command in cron job or scripts then consider SSH keys to get rid of the passwords.

Some more examples:

$ tar cvjf - * | ssh [email protected] "(cd /dest/; tar xjf -)"
$ tar cvzf - mydir/ | ssh [email protected] "cat > /backups/myfile.tgz"
$ tar cvzf - /var/www/html | ssh [email protected] "dd of=/backups/www.tar.gz"
$ ssh [email protected] "cat /backups/www.tar.gz" | tar xvzf -
$ tar cvjf - * | ssh [email protected] "(cd /dest/; tar xjf - )"

Make sure you read the tar command/ssh command/bash command man page for more info:
$ man tar
$ man bash
$ man ssh

A note about SSHFS – a FUSE filesystem

You can use sshfs to mount a remote directory and run tar command:
mkdir /data/
sshfs [email protected]:/ /data/
tar -zcvf /data/file.tar.gz /home/vivek/

Posted by: Vivek Gite

The author is the creator of nixCraft and a seasoned sysadmin and a trainer for the Linux operating system/Unix shell scripting. He has worked with global clients and in various industries, including IT, education, defense and space research, and the nonprofit sector. Follow him on Twitter, Facebook, Google+.

40 comment

  1. The use of this and your examples seem rather untypical. Why pipe it through “ssh” if you’re just transfering a tar.gz to the other side. You could just create the tar.gz and scp it.

    Also, the use of “cat” in your examples is completely unnecessary.

    I came here hoping to find an example like this (i.e. transferring a directory recursively over ssh). So, for the next guy:

    tar cvf – /data | ssh otherhost tar xvf –

    1. So how exactly would your tar up a 10GB partition with less than 1GB of space left? The original author’s solution works very nice, as does your solution. They are just used for two separate things.

  2. Hi Vincent,

    You may want to do this to get around limitations in older implementations of SSH that do not allow for large file transfers (larger than 2GB). I had recently run into this problem and the only workable solution was to tar over ssh to get around it.

  3. The whole point of this command is to help you when you have a filesystem full and need to tar files but don’t have enough space to store the tars. You can pipe the tar through ssh so that later you may also delete the files and place the tar into the original filesystem.

  4. i dont know how to use to tar on network i was used 192.168.200.178 machine i use this /mydata folder how to transer using tar over network destination system is 192.168.200.200. any one help me.

  5. The opposite side – which is the more common case, where you want to pull data from server, as opposed to making the server initiate connection and pushing data:

    ssh [email protected] "tar jcf - /srv/gdr/gdr.geekhood.net/gdrwpl" > gdrwpl_backup.tar.bz2

    This might be useful if you are behind a firewall

  6. Vincent:
    The method of piping tar through SSH is faster than SCP not because SCP is slow (the transfer rate would theoretically be exactly the same), but because it saves a lot of time by parallelizing the tar.gz creation with the transfer. This is even more true if the source system only has one hard drive (or the only hard drive with enough free space to do the tar.gz is the same as the one you want data from).

    If you have a few GB of loose files to copy into a .tar.gz on the remote side (say, for doing a backup), piping the output through ssh is faster because the source hard drive can just read continously the whole time and the destination can write at the same time. If you’re creating the .tar.gz on the same hard drive, you take a huge penalty for all the seeking it has to do; it as to read a bit, write it to the tar, read a bit more, write it to the tar, etc.

    Even if you have a second hard drive (or a crapload of RAM), you’re still taking longer if you make the .tar.gz first because there’s creation + transfer time instead of just transfer time.

  7. Hi,
    thank you for your script snippets, one of these is just backing up some giga bytes across the network. But I notices a typo, a unnecessary “ssh” behind some of the pipe symbols. For example:
    # tar cvzf - /wwwdata | ssh ssh [email protected] "cat > /dev/nst0"

  8. Here’s one that worked for me recently:

    I had to copy all the files from server A to a directory in server B (in order to have full replica of A), using man-in-the-middle server (because that IP was the only one allowed to connect).

    The trouble was that I only had sudo rights on the first server and there were absolutely all ports closed (both ways) except incoming 22 for my ip and incoming 80 and 443 for serving web. No way to ssh out of that box (fw blocked outgoing syn packets)

    First I had to “initialize” sudo so that I wouldn’t be asked a password which would later be asked within the pipe so I can’t provide it then (you recognize it by the infinite delay in the beginning while files are not appearing to the other side).

    ssh -Ct serverA "sudo hostname
    Password:

    -C uses compression,
    -t forces assigning a terminal (RHEL 5.1 by default requires terminal)

    I guess this can be achieved also by just sshing in and issuing the same command there. Hostname is just a random command to get sudo to ask for password (which it remembers for the next 15 minutes).

    Now for the fun part:

    ssh -Ct "stty -onlcr; sudo tar -cpf - -X /tmp/exclusion.list / 2> /dev/null" | ssh serverB "cd /tmp; tar cvpf -"

    stty -onlcr fixes a problem that arises with using forced terminal: for every CR (0x13) an extra LF character will be injected (0x13) for proper displaying on terminal. Only we’re actually not using a terminal but passing the bitstream through the ssh tunnel to tar.

    -p preserves files’ permissions
    -X specifies an exclusion file (directories I don’t want to be copied like /dev, /proc and /sys)
    / is what I want to be tarred :)
    2> /dev/null sends tar commentary to the darkest of places. Without it you’ll get tar’s own chatter within the data stream.

    Hope this will be useful to someone (like myself, later on)

  9. I recently needed to copy entire directory structure from one machine to another, preserving symlinks, owners and dates. I’ve done this tens of times before with tar and ssh but this time it didn’t work.

    Although I didn’t use the -h option, tar nevertheless followed symlinks and not recreated them on other side. Distro was Ubuntu 8.04. When I tried it with a small set of files, it worked, though, but I needed the entire tree. I never figured it out why it acted like that.

    I was finally able to solve my problem by using rsync and after inital setup it worked very well. So for anyone stumbling over the same rock, here’s some examples getting it done with rsync:
    http://www.commandlinefu.com/commands/matching/rsync/cnN5bmM=/sort-by-votes

  10. Is there some simple method to copy file through some kind of “ssh chain” ?
    Assuming that I’m at “homepc” , can connect via SSH to “remote1” , and from “remote1” I can only connect SSH to “remote2” .

    Which is the “one-liner” to copy a file from “remote2” to “homepc” ?
    Let’s say it’s “remote2:/repository/somefile.war” (I googled around but not found easy method)

  11. In my experience, “rsync over ssh” is much faster than “tar | ssh”. Both are faster than scp, though. The only advantage of “tar | ssh”, IMHO, is not needing to have rsync in the remote host…

  12. I want to do exactly this to a Windows machine running ssh

    I’m trying something like

    tar zcvf - /somedir | ssh [email protected] " > /backup/wwwdata.tar.gz"

    but there is no “cat” in windows, and the similar commands (echo, type, more) doesn’t seem to take input from stdin. Any ideas?

  13. If, for one reason or another, you call ssh with the `-t` param (as mentioned by Henno) or have set `RequestTTY yes` in your ssh_config, tar will give strange errors like
    `tar: Skipping to next header
    tar: Exiting with failure status due to previous errors`
    or
    `tar: A lone zero block at 21625
    tar: Exiting with failure status due to previous errors`
    These will go away by adding ssh parameter `-T Disable pseudo-tty allocation.`, or if you need `-t` by prepending `stty -onlcr; ` to the remote command as workaround (thx Henno!).

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