If I recall well the /sbin directory first appeared in HP/UX, and the name stood for 'Static binaries'. Its reason for existence was that with the introduction of shared libraries the file with the C-library had become a single point of failure. Therefore this sbin was introduced to hold Statically linked executables for the most important commands needed to fix a broken system (sh, ls, mv, cp, find, tar, fsck etcetera). With this directory earlier than /bin in his PATH the administrator could at least restore a working libc.so file. And, while we are at it, the name 'executable' was not commonly used: they were called 'binaries' (except in IBM mainframe terminology were they were called 'load modules'). Only much later the habit of /sbin = System binaries emerged. An important reason to split /bin vs. /usr/bin and /lib vs. /usr/lib etc. was that the root file system had to be kept small. The fsck program, while at work, builds tables. If possible, they stay in memory, but if memory runs out fsck writes them to disk. However, you don't want them to be written to an untrusted/unchecked file system, and certainly not to the file system currently under repair. Since the root file system has to be checked before the others, it had to be small enough so ensure that fsck could run memory-based only. Therefore: the /bin, /lib and other root-fs based directories held the minimal stuff needed for booting and for repairs/restores, while all the rest had to go into the "overflow" directories /usr/bin, /usr/lib etc (and, obviously, /usr was a separately mounted partition). Remember: those were the days that every reboot included a full fsck on all your partitions. -- Hendrik-Jan Thomassen <hjt(a)ATComputing.nl> AT Computing 6546 BE Nijmegen NL Fax +31 24 352 72 92 info(a)atcomputing.nl www.atcomputing.nl 'If you think education is expensive, then try ignorance.'