> perl -le "                       print 'x',POSIX::O_RDWR();"
Undefined subroutine &POSIX::O_RDWR called at -e line 1.
 > perl -le "            use POSIX; print 'x',POSIX::O_RDWT();"
O_RDWT is not a valid POSIX macro at -e line 1
 > perl -le "use strict;            print 'x',POSIX::O_RDWR();"
Undefined subroutine &POSIX::O_RDWR called at -e line 1.
 > perl -le "use strict; use POSIX; print 'x',POSIX::O_RDWT();"
O_RDWT is not a valid POSIX macro at -e line 1
 > perl -le "use strict;            print 'x',POSIX::O_RDWR;"
Bareword "POSIX::O_RDWR" not allowed while "strict subs" in use at -e line 1.
Execution of -e aborted due to compilation errors.
 > perl -le "use strict; use POSIX; print 'x',POSIX::O_RDWT;"
Bareword "POSIX::O_RDWT" not allowed while "strict subs" in use at -e line 1.
Execution of -e aborted due to compilation errors.