2021/06/09

Cookbook: Running commands remotely

(I frequently write throw-away scripts in Gauche, and it occurred to me that they can be a nice source of cookbook recipe. I'll write them up as I come to useful snippets.)

With run-process or do-process, you can invoke external commands (ref:gauche.process). One of their interesting feature is that you can run the commands on a remote host, if you have ssh access with public-key authentication to it.

Just add :host keyword argument.

(do-process '(ls) :host "remote.example.com")
 ;=> you see listing of your home directory at remote.example.com

Stdio is forwarded to the local process, so as process exit status. The :directory keyword argument works, though it is relative to your home directory of the remote machine. So, you can mix local execution and remote execution pretty much seamlessly.

The following snippet pushes local commits to the repo, pulls them on the remote machine, rebuild and restart the service. The return value of do-process is a boolean indicating command success or failure, so combining with and is like && in shell scripts.

(and (do-process '(git push) :directory *local-dir*)
     (do-process '(git pull) :host *host* :directory *remote-dir*)
     (do-process '(make)     :host *host* :directory *remote-dir*)
     (do-process '(make restart) :host *host* :directory *remote-dir*))

Tags: Cookbook, gauche.process