app/src/main/java/org/sakaiproject/nakamura/app/NakamuraMain.java
private static String getSlingHome(Map<String, String> commandLine) {
		String source = null;

		String slingHome = commandLine.get("c");
		if (slingHome != null) {

			source = "command line";

		} else {

			slingHome = System.getProperty(SharedConstants.SLING_HOME);
			if (slingHome != null) {

				source = "system property sling.home";

			} else {

				slingHome = System.getenv(ENV_SLING_HOME);
				if (slingHome != null) {

					source = "environment variable SLING_HOME";

				} else {

					source = "default";
					slingHome = SharedConstants.SLING_HOME_DEFAULT;

				}
			}
		}
		System.setProperty(SharedConstants.SLING_HOME, slingHome);

		info("Setting sling.home=" + slingHome + " (" + source + ")", null);
		return slingHome;
	}
private static String getSlingHome(Map<String, String> commandLine) {
		String source = null;

		String slingHome = commandLine.get("c");
		if (slingHome != null) {

			source = "command line";

		} else {

			slingHome = System.getProperty(SharedConstants.SLING_HOME);
			if (slingHome != null) {

				source = "system property sling.home";

			} else {

				slingHome = System.getenv(ENV_SLING_HOME);
				if (slingHome != null) {

					source = "environment variable SLING_HOME";

				} else {

					source = "default";
					slingHome = SharedConstants.SLING_HOME_DEFAULT;

				}
			}
		}
		System.setProperty(SharedConstants.SLING_HOME, slingHome);

		info("Setting sling.home=" + slingHome + " (" + source + ")", null);
		return slingHome;
	}
Define the sling.home parameter implementing the algorithme defined on
the wiki page to find the setting according to this algorithm:
<ol>
<li>Command line option <code>-c</code></li>
<li>System property <code>sling.home</code></li>
<li>Environment variable <code>SLING_HOME</code></li>
<li>Default value <code>sling</code></li>
</ol>

@param args
The command line arguments
@return The value to use for sling.home