UNIX history made easy

[John F. Haugh II]

In article <1858 at texsun.Central.Sun.COM> jthomp at wintermute.Central.Sun.COM (Jim Thompson  Sun Dallas IR) writes:
>'sticky bit', John, 'sticky'.  And back then it was on files,
>not directories.  (Well, ok,  you could probably set it on
>a directory (damn, where did I put that V6 listing?) but it
>had no meaning.  If you set it on an executable file, that file's
>swap image would stay on  the swap area after the program exited.
>It was a wonderful hack to reduce overhead of often used programs.
>
>In recent BSD editions, the sticky bit has be overloaded for
>directories to (not) permit 'unlink' operations in directories
>otherwise writtable by the process in question.

I can't believe I have to explain tacky bits to Jim.  Jim Thompson,
for those of you who -have- had your heads under rocks all your
lives is the inventor of the Set-GID bit.  Dennis Ritchie was
giving a lecture on his recently patented Set-UID bit [ which was
one of the first software patents -ever- ] and Jim very sarcastically
said `Why don't you do it for groups too', and the idea was born.

The purpose of the ``tacky bit'' was to get around the incredibly
small disk partitions which were prevalent in the early 1970s.
Any PC user is painfully aware of how small PC disks were [ typically
around 10MB ].  Well, PDP-11 disks ran as small as 5MB each,
often requiring 10 or 20 disk drives just to make a reasonably
large /usr partition.

What the tacky bit did was cause /unix to scan each subdirectory
of a directory on file name lookups.  So it would be possible to
have ten or twenty subdirectories each with a different mounted
file system all look like a single system image.  The introduction
of the RK07 disk drive did away with the need for the tacky bit,
and it faded into obscurity with a few other worthless ideas, like
`Save Stack on Swap', which saved a process's stack on the swapper
after it exited.
-- 
John F. Haugh II                        +-Things you didn't want to know:------
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