$ /usr/vac/bin/xlc -o korn.bin korn.c "korn.c", line 1.18: 1506-045 (S) Undeclared identifier unix. $ /usr/vac/bin/xlc -qversion IBM XL C/C++ for AIX, V10.1 Version: 10.01.0000.0007 $ oslevel -s 6100-05-01-1016