This document shows how you can use JMeter to perform more automated (non-interactive) testing.

Requirements

This article assumes that you:

know the basics of JMeter
have an existing test plan
have a bit of knowledge on using variables in test plans
have touched on remote testing (from GUI is fine)

Set up

In your existing test plan, make sure that any variations in testing make use of functions or variables. For example, if running a HTTP sampler, use HTTP Request Defaults to specify a host as {{$\{+P(targetHost,localhost)\}}}. Other useful places for parameterisation might include number of threads, ramp-up period or scheduler duration in a thread group, using a format of {{$\{+P(threadgroup.threads,500)\}}}  (The {{+P}} function is shorthand for {{+property}}. See the \[http://jmeter.apache.org/usermanual/functions.html#__P user manual\] for more info on using this function).

Save your test plan and properties file to a directory.
Create a properties file containing all your variables. E.g. mytest.properties could contain threadgroup.threads=100, targetHost=my-target-host.com
The test plan does not need Listeners, as this will be configured via parameters. This will improve performance on the testing.
Run the test mode in stand-alone mode (i.e. no remote servers): jmeter -n -t load_test.jmx -l load_test_report.jtl -q mytest.properties -j mytest.log
The "-q" parameter defines an additional property file, which is the equivalent of setting properties for the contents of the file using the -J parameter. These parameters are not sent to remote servers; for that one can use the -G parameter. The -G parameter can reference either a property in the format of -Gprop=val or a properties file, such as -G./myglobal.properties
Properties can be referenced anywhere in the test plan using the +P() function - e.g. ${+P(propname)}
There is no way currently to predefine variables, however the User Defined Variables table on the Test Plan can be used to create variables from properties. For example:

Name:	Value:
HOST	`${__P(host,localhost)`}

On all client machines, start up JMeter server, ensuring that firewall is not blocking connections (clients must all be on the same subnet).
On JMeter controller (the host initializing the test), run the test with the -R parameter (can be run using -r and specfiying hosts in jmeter properties file):
jmeter -n -t load_test.jmx -l load_test_report.jtl -Gmytest.properties -j mytest.log -R remotehost1,remotehost2 ${GLOBAL_VARS}

Note that load injection to targets will be a increased as a ratio of number of threads per thread group multiplied by number of client machines.

A bash script similar to the following could be used to start up jmeter (called jmeter_test_wrapper.sh for example):

#!/bin/sh

loadtest="myloadtest"
GLOBAL_VARS=""
REPORT_DIR=/tmp
JMETER_PROPERTIES=jmeter.properties
JMETER_CUSTOM_PROPERTIES=mytest.properties
# If set as an environment var, then use it, otherwise leave it unset.
HOST_LIST=${HOST_LIST:+"-R ${HOST_LIST}"}

# Had an issue with -Gglobal.properties file, so parsed this into individual properties.
for var in `grep -vE "^#|^$" ${JMETER_CUSTOM_PROPERTIES}`; do
        GLOBAL_VARS="-G${var} ${GLOBAL_VARS}"
done

# But after testing, it does work as expected.
GLOBAL_VARS="-G${JMETER_CUSTOM_PROPERTIES}"

if [ -f ${loadtest}.jmx ]; then
        echo "Running ${loadtest} with:"
        echo -e "               -----------------------
        $JMETER -n
                -t ${loadtest}.jmx
                -l ${REPORT_DIR}/${loadtest}.jtl
                -p ${JMETER_PROPERTIES}
                ${GLOBAL_VARS}
                ${HOST_LIST}
                -j ${REPORT_DIR}/_${loadtest}.log
        -----------------------"
        $JMETER -n \
                -t ${loadtest}.jmx \
                -l ${REPORT_DIR}/${loadtest}.jtl \
                -p ${JMETER_PROPERTIES} \
                ${GLOBAL_VARS} \
                ${HOST_LIST} \
                -j ${REPORT_DIR}/_${loadtest}.log
else
        echo "Could not find test plan for ${loadtest}"
fi

For a local test, you could run: ./jmeter_test_wrapper.sh
For a remote test, it can be modified as HOST_LIST="192.168.1.10,192.168.1.12" ./jmeter_test_wrapper.sh
Now all you need to do is make sure the servers are running and add the above command into scheduler.