How to write a file a file via ssh

Question

I want to write a file in the Machine B under

/home/test whose permissions are root:root and rwxr-xr-x.

I have an account on the Machine B, named testUser. When logged to the Machine B with this user, I can use sudo to write a file under /home/test.

However now I want to use ssh command on the Machine A to order testUser@MachineB to write a file under /home/test via ssh, but I got the Permission denied message when using scp to copy a file to /home/test. I want to avoid typing password so that these action can be done using a script. Is there any way to solve it?

By the way, I've set ssh-key to login without password authentication.

Is using setuid on a executable file on Machine B to write a file under /home/test a good way?

Answer 1

You could configure sudo to allow the command cp foo /home/test/ without a password, and then use this command:

ssh testUser@MachineB 'cat > foo && sudo mv foo /home/test/' < my_file

Piping data through ssh to a command of your choice on the other end is the general trick here. You can probably find a dozen other ways to accomplish your goal using variations of this.