/usr/lib/mysql-testsuite/t/long_tmpdir-master.opt is in percona-server-test-5.6 5.6.22-rel71.0-0ubuntu4.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 | --tmpdir=$MYSQLTEST_VARDIR/tmp/long_temporary_directory_path_123456789_123456789_123456789_123456789_123456789_123456789_123456789_123456789
|