Latex Dollar Sign \\ How do I signify Linux Environment Variables in latex?

I am aware to output dollar signs you escape it with \ such that:

\$ 开发者_开发百科         % prints '$' 

However, I can't print something like

\$ JAVA_HOME       % prints '$ JAVA_HOME'

The space in between the $ and JAVA_HOME is what's annoying. How can I make it so it's one word?

remove the space? \$JAVAHOME gives what I expect:

$ grep JAVA test.tex 
\$JAVAHOME

$ ps2ascii test.ps
$JAVAHOME