ftp://ftp.uga.edu/pub/CPAN/modules/by-category/04_Operating_System_Interfaces/  direct

[DIR]AIX/  direct  800+ twin directories
[DIR]Env/  direct  290+ twin directories
[DIR]Hardware/  direct  470+ twin directories
[DIR]Mac/  direct  950+ twin directories
[DIR]POSIX/  direct  470+ twin directories
[DIR]Async/  direct  270+ twin directories
[DIR]BSD/  direct  570+ twin directories
[DIR]AudioCD/  direct  250+ twin directories
[DIR]B/  direct  1000+ twin directories
[DIR]Chipcard/  direct  240+ twin directories
[DIR]Errno/  direct  410+ twin directories
[DIR]Fcntl/  direct  670+ twin directories
[DIR]FreeBSD/  direct  900+ twin directories
[DIR]HPUX/  direct  380+ twin directories
[DIR]Linux/  direct  1000+ twin directories
[DIR]MSDOS/  direct  340+ twin directories
[DIR]MVS/  direct  340+ twin directories
[DIR]OS2/  direct  1000+ twin directories
[DIR]Quota/  direct  310+ twin directories
[DIR]Signal/  direct  220+ twin directories
[DIR]Slackware/  direct  530+ twin directories
[DIR]Sys/  direct  800+ twin directories
[DIR]VMS/  direct  630+ twin directories
[DIR]BS2000/  direct  210+ twin directories
[DIR]Be/  direct  270+ twin directories
[DIR]Device/  direct  320+ twin directories
[DIR]GTop/  direct  260+ twin directories
[DIR]Ioctl/  direct  260+ twin directories
[DIR]L4Env/  direct  240+ twin directories
[DIR]MacOSX/  direct  510+ twin directories
[DIR]Proc/  direct  270+ twin directories
[DIR]Schedule/  direct  280+ twin directories
[DIR]Passwd/  direct  200+ twin directories
[DIR]RRDTool/  direct  220+ twin directories
[DIR]SGI/  direct  490+ twin directories
[DIR]Shell/  direct  300+ twin directories
[DIR]Solaris/  direct  1000+ twin directories
[DIR]Sun/  direct  420+ twin directories
[DIR]Unix/  direct  490+ twin directories