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If you run jtreg by making a symbolic link to linux/jtreg in another directory already on your PATH you will need to export a JT_HOME environmental variable.
Caveats
If your version of Xcode is older than 3.2.5, the 32-bit build (java -d32 ...) won't start, but the 64-bit build will.
XToolkit currently does not function under 32-bit in universal builds.
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