perl -le "                       print 'x',POSIX::O_RDWR();"
perl -le "            use POSIX; print 'x',POSIX::O_RDWT();"
perl -le "use strict;            print 'x',POSIX::O_RDWR();"
perl -le "use strict; use POSIX; print 'x',POSIX::O_RDWT();"
perl -le "use strict;            print 'x',POSIX::O_RDWR;"
perl -le "use strict; use POSIX; print 'x',POSIX::O_RDWT;"