ftp://ftp.wu-wien.ac.at/pub/src/lang/CPAN/modules/by-category/04_Operating_System_Interfaces/  direct

[DIR]VMS/  direct  1070+ twin directories
[DIR]Unix/  direct  1616+ twin directories
[DIR]Sys/  direct  1637+ twin directories
[DIR]Solaris/  direct  2315+ twin directories
[DIR]Shell/  direct  835+ twin directories
[DIR]Schedule/  direct  465+ twin directories
[DIR]SGI/  direct  1029+ twin directories
[DIR]Quota/  direct  625+ twin directories
[DIR]Proc/  direct  641+ twin directories
[DIR]POSIX/  direct  1721+ twin directories
[DIR]OS2/  direct  2743+ twin directories
[DIR]Mac/  direct  2034+ twin directories
[DIR]MVS/  direct  514+ twin directories
[DIR]MSDOS/  direct  519+ twin directories
[DIR]Linux/  direct  4699+ twin directories
[DIR]Ioctl/  direct  389+ twin directories
[DIR]Hardware/  direct  1098+ twin directories
[DIR]HPUX/  direct  800+ twin directories
[DIR]GTop/  direct  389+ twin directories
[DIR]Fcntl/  direct  1478+ twin directories
[DIR]Errno/  direct  839+ twin directories
[DIR]Env/  direct  634+ twin directories
[DIR]Device/  direct  723+ twin directories
[DIR]Be/  direct  474+ twin directories
[DIR]BSD/  direct  1568+ twin directories
[DIR]B/  direct  3998+ twin directories
[DIR]AudioCD/  direct  394+ twin directories
[DIR]Async/  direct  484+ twin directories