Master Remote Command Execution with SSH: From Simple Commands to Scripts

Remote Command Execution

SSH is the fundamental tool for remote connections on Linux, but its power goes far beyond simple login; it can automate many remote operations.

Running a Single Command

You can execute df -h on a remote host without logging in:

ssh [email protected] "df -h"

Running Multiple Commands

Separate commands with a semicolon and wrap them in quotes: ssh [email protected] "pwd; cat hello.txt" The first command returns the home directory, and the second displays the file content. When using multiple commands, always quote the entire command string to ensure all commands run remotely.

Executing Interactive Commands

Commands that require a TTY (e.g., sudo ls /root or top) fail unless you allocate a pseudo‑terminal with -t: ssh -t [email protected] "sudo ls /root" Adding -t forces SSH to keep the session open until the interactive command finishes.

Running Multi‑Line Commands

You can embed several lines of commands inside a quoted string, using mixed single and double quotes when needed.

Executing Local Scripts Remotely

Create a script test.sh locally (e.g., containing ls and pwd) and pipe it to the remote host: ssh [email protected] < test.sh To pass arguments, use the -s option with bash:

ssh [email protected] 'bash -s' < test.sh helloworld

Executing Scripts Stored on the Remote Server

If the script resides on the remote machine, invoke it with its absolute path: ssh [email protected] "/home/nick/test.sh" Arguments can be supplied after the script path, and they appear as $0 and $1 inside the script.

Summary

This article demonstrates the basic SSH remote‑operation techniques—running single or multiple commands, handling interactive sessions, executing multi‑line commands, and running both local and remote scripts—laying the groundwork for more complex automation tasks.