transferring data on the network - c++

Question

Please suggest some solutions. Normally I ssh to an other computer and do some calculations there then I just sftp when I need to transfer data from that machine to my local host machine. This time around I want to send some input from my local machine to the remote machine, the remote machine will do its bit and then send me back its output. How can I automate this process so that it repeats as many times as I specify on my local machine? Is this quite complicated to do. Please let me know if I have not given enough detail.
This is the manual process.
ssh username#remote.machine !ssh to remote machine
program.o input.dat !supply input to the program
sftp username#remote.machine !ftp to remote machine from another terminal
get output.dat !output.dat was produced by program.o
!open an other terminal
another_prog.o output.dat !run another program on my local machine
!Then repeat. Some times I may compile using a make file.
I want to automate this process. what are my options. The programs are written in any number of languages like C++/c, fortran. I am an o.k programmer but I have never had a situation where I had to do the above, so teach me :)
Both my local and remote machines are linux/ubuntu

Answer 1

Set up private/public key login between the systems you want to automate. See e.g. here for an explanation on how to do it: https://wiki.archlinux.org/index.php/SSH_Keys - note that you will greatly benefit from the use of ssh agents (and e.g. keychain, if applicable)
ssh can be used to remotely execute anything, passing whatever you write to its stdin to the remote process' stdin.
Examples:
echo test | ssh yourmachine.example.com xargs echo
This will call the remote xargs program, which will read the "test" string from stdin, passed to it via ssh, which you passed it in the first piped echo command, and it (xargs) will execute the remote echo binary with the string "test" as its argument, returning whatever the remote "echo" command writes to its stdout to your own ssh command's stdout, which is your terminal. In short, this is a complicated way of invoking echo on the remote machine to echo a an arbitrary string and return it to you.
echo more tests | ssh yourmachine.example.com "cat > /tmp/file.txt"
This will create a file /tmp/file.txt on the remote machine with the contents "more tests" (because the remotely executed cat command will read the "more tests" string from its stdin and the shell redirect will write its output to /tmp/file.txt - note that the quotes are required because you want to pass the "cat > /tmp/file.txt" string as a whole, integral command to the remote system).
cat input_data.txt | ssh yourmachine.example.com /usr/bin/my_number_cruncher > output_data.txt
This will transfer the contents of the input_data.txt file to the remote machine, execute the /usr/bin/my_number_cruncher binary and pass it to its stdin, and return whatever this program writes to stdout to the output_data.txt file on your local machine.
Using all these combined you can see it's trivial to transfer files and data among machines using ssh, invoke remote programs, and transfer the results back to you.

Answer 2

you can use the scp command for copying the file from remote to local or from local to remote.
for automation you can write the script for the same.