Single command to launch an agent program, which controls the agent computer and communicates with the master. Jenkins assumes that the executed program launches the agent.jar program on the correct machine.

A copy of agent.jar can be downloaded from here.

In a simple case, this could be something like ssh hostname java -jar ~/bin/agent.jar.

Note: the command can't rely on a shell to parse things, e.g. echo foo > bar; baz. If you need to do that, either use sh -c or write the expression into a script and point to the script.

It is often a good idea to write a small shell script, like the following, on an agent so that you can control the location of Java and/or agent.jar, as well as set up any environment variables specific to this node, such as PATH.

#!/bin/sh
exec java -jar ~/bin/agent.jar

You can use any command to run a process on the agent machine, such as RSH, as long as stdin/stdout of the process on the master will be connected to those of java -jar ~/bin/agent.jar on the agent machine eventually.

In a larger deployment, it is also worth considering to load agent.jar from a NFS-mounted common location, so that you don't have to update this file on every agent machines every time you update Jenkins.

Setting this to ssh -v hostname may be useful for debugging connectivity issue.