Questions on "SSH"

linux_2007_ · 05-11-2007, 05:33 PM

I am writing a script file in linux SUSE os. One line of this script is SSH in order to connect to a remote server. I can do that and the connection is made. Now I have 2 questons:

1. How can I run a remote command (I mean automatically)?

2. How can I keep this connection "open" and go to the next line in the script file (to run the next command)?

I appreciate any help or advice on these, I really need them.

Matir · 05-11-2007, 05:35 PM

If you want to run a whole batch of commands via SSH, you could do something like:

Code:

ssh user@remote bash<<<EOF
command1
command2 with args
command3
EOF

This spawns a bash shell on the remote system and passes it those commands. You may need the -t option to SSH, sometimes I have, sometimes I haven't. (It depends on the SSH version)

linux_2007_ · 05-11-2007, 06:51 PM

Thanks Matir
.

linux_2007_ · 05-11-2007, 06:54 PM

Are "bash<<<EOF" and the last line "EOF" the exact syntax that I should type and put in the script file?

If you have any advice for my 2nd question as well, that would be a great help.

Thanks.

Matir · 05-11-2007, 10:10 PM

There was a typo in my original post, it's supposed to be "<<", not "<<<". My apologies.

You can replace both instances of EOF with any string that is the same, though EOF is a convention for "End of File".

This will continue and allow multiple commands to be executed on the remote system. If you want to mix local and remote execution, it will be much more complex. Perhaps you can provide an example if this does not work for you.

linux_2007_ · 05-12-2007, 02:16 AM

Quote:

Originally Posted by Matir

There was a typo in my original post, it's supposed to be "<<", not "<<<". My apologies. This will continue and allow multiple commands to be executed on the remote system.

No problem, actually I noticed a little after I posted my message. My batch file including several "remote" commands works very well now.

Quote:

Originally Posted by Matir

If you want to mix local and remote execution, it will be much more complex. Perhaps you can provide an example if this does not work for you.

Regarding my 2nd question, all I need is to run SSH to connect to a remote server and keep the connection open as I need to run a software which although is installed on my local PC, for it to be excecuted, it needs license checking and that is on the remote server (I should mention that I have permission from the software producer and the remote server owner both, so it is totally legal, but getting all this working is my own resposibility). As such the script file will be something like this:

...
ssh user@remote
---->> now we are in the remote server (can see the prompt)
---->> then, here I need to run the software installed on my computer without closing the connection (if it gets closed, clearly we are back on the local machine, but the program cannot be run).

In other words, the connection has to be kept on in the background while going back to the local PC for executing the software. I have heard there is a definite solution for it but could not find any answer yet.

I hope this makes it a bit clearer. Any advice?

Thanks
.

Matir · 05-12-2007, 09:02 AM

You'll probably need to add a port-forward or something similar, but look into the -f option to ssh. You might need to split the execution of remote commands and the port forwarding into two ssh sessions (or get much more complex in your scripting).