help with text-append over SSH ? - dd: unknown operand >>

Giorgos Keramidas keramida at
Mon Oct 15 11:32:02 PDT 2007

On 2007-10-12 16:43, Juri Mianovich <juri_mian at> wrote:
>--- Giorgos Keramidas <keramida at> wrote:
>>On 2007-10-11 16:49, Juri Mianovich
>><juri_mian at> wrote:
>>> I have an account on a system where I cannot log in over SSH, but I
>>> _can_ run a limited set of commands remotely, over SSH.  (I am in a
>>> jail of some sorts).
>>> I want to append the contents of a local text file to the contents
>>> of a remote text file, over SSH.
>>> Normally, I would do this locally with:
>>> cat file1 >> file2
>>> But again, file2 is remote, and I can't log in there... I have
>>> access to the 'echo' command and the 'dd' command (among others) on
>>> the remote host ... so for instance, I can do things like this:
>>> ssh user at host rm -rf filename
>>> So, with all that in mind, how do I append the contents of a local
>>> file to a remote file, over SSH, using either 'echo' or 'dd' ?
>> Try running:
>>     cat file1 | ssh user at host "dd >> file2"
> Thank you - I do indeed need to use 'dd' because I don't have access
> to 'cat' in the chroot.
> However, when I use your example, I get this error:
> dd: unknown operand >>
> So I have something off a bit ... help ?

Then you are not running a 'standard shell', but some sort of local
hack and/or wrapper:

    kobe-> ssh server "echo 'hello world' > foo"
    kobe-> ssh server "od -c foo"
    0000000   h   e   l   l   o       w   o   r   l   d  \n
    kobe-> echo hello new world | ssh server "dd >> foo"
    0+1 records in
    0+1 records out
    kobe-> ssh server "od -c foo"
    0000000   h   e   l   l   o       w   o   r   l   d  \n   h   e   l   l
    0000020   o       n   e   w       w   o   r   l   d  \n

I'm sorry, but I don't think you can get effective "help" from the
FreeBSD lists.  You will have to ask for specific guidelines and help
from your hosting provider.  Anything else will be guesswork and may
break without any sort of notice in the future, when your host decides
to install a "new" "security fix" to their custom shell.

- Giorgos

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