some times you need to copy a file or directory from your machine to another machine using command line, if so you can use the scp command :

suppose that the file needed to be copied /home/mostafa/file.txt, and you have access to the other machine

$ scp /home/mostafa/file.txt

this command will copy the file.txt to the the path /home/mostafa/file.txt in the remote machine

also you can copy files between 2 remote machine with the same command as follows:

$ scp :/home/mostafa/