|
ssh/sftp/scp: Use remote system without always switching tools/connections?
First of all: I know my way around the command line, at least enough to get by, but I'm far from being any sort of unix expert. I'm a programmer (mostly C-derived languages), and I can do basic shell scripts, but I'm no script-fu wiz.
I have basic familiarity with using ssh (for a secure remote shell), sftp and scp. But I've noticed I typically need to switch between them a lot for various tasks (which also means lots of opening/closing ssh connections to the same remote machine). From what I can tell, this seems to be due to limitations in each of them.
Maybe I'm wrong, but as I understand things:
ssh shell:
Can do: Pretty much anything you can do at a normal shell.
Can do: Multiple commands in one session/connection.
Cannot do: File transfers.
Cannot do: "batch" mode (like sftp) that'll bail out at the first error.
sftp:
Can do: Multiple commands in one session/connection.
Can do: Transfer files.
Can do: Delete files and empty dirs.
Can do: Explore/query the remote filesystem.
Can do: Batch mode (-b) that'll bail out at the first error.
Cannot do: Transfer/delete entire non-empty directory trees.
scp:
Can do: Transfer entire non-empty directory trees.
Cannot do: Multiple commands in one session/connection.
Cannot do: Delete things.
Cannot do: Move/rename things.
So, for example, suppose I want to do all the following, and automate it in a script:
1. Upload a bunch of misc standalone files to various places (ie, wildcards won't help).
2. Delete the tree 'foo'.
3. Upload a new 'foo' tree.
4. Do some logic, both remote and local.
5. Some other step that completely depends on the results of #4
As far as I'm aware:
#1 needs to use sftp (could use scp, but that would be wasteful - a new connection for every file?).
#2 needs to be ssh (could use sftp in theory, but that's be a royal PITA).
#3 needs to be scp (again, sftp would be theoretically possible, but a royal pain).
#4 can only be ssh.
#5 could end up needing to be anything.
So, AFAIK, I can't just simply pass a block of script in batch mode to ssh or sftp. That simple set of tasks involves switching between all those separate programs, and with each making a separate new connection.
Now, I can certainly do all that. But it seems to me I must be missing something.
Is there some better way to do all of this? To do it all in one connection? Or not have to keep switching between the different tools?
|
