Running Remote Commands Interactively with SSH
I often need to run a command on a remote server without starting a full interactive session. I want the program to keep all the characteristics of a local process while running on the remote server.
At first, I just used the ssh command, specifying the server and the command to run:
ssh server command
This method doesn’t work well for programs that require a pseudo terminal, like Neovim. To fix that, I tried the -t option to force pseudo terminal allocation. With it, programs like ls display colors, but the user environment isn’t loaded. In that case, I need to pass the --color option to ls. Even so, programs like Neovim fail because the shell doesn’t behave as interactive and ANSI codes aren’t processed correctly.
ssh -t server command
To get a fully working shell that loads its configuration, I tell the shell to run as interactive. In zsh, that’s the -i option. I also use the -c option to run the desired command:
ssh -t server "zsh -ic 'command'"
This way, I run complex commands from my local machine without opening an interactive remote session, which improves convenience and security. This method is useful in scripts that need to manipulate the server, since it doesn’t leave the session open.
The only drawback is that the command runs in a new shell, without keeping environment variables and other settings after it finishes. I can attach to a tmux or screen session, but that makes it hard to identify where the command starts and ends, preventing output capture.
In any case, here is the command to create a tmux session, or attach to an existing one, and then run the command:
ssh -t server "tmux new-session -d -s persistent || true; \
tmux send-keys -t persistent \"zsh -ic 'command'\" Enter; \
tmux attach -t persistent"
To get a remote shell with all the settings and environment variables while keeping state between sessions, we would need a new shell. But that’s a project for another day.
Video with a detailed explanation: