Re: [9fans] Novice question - run as other

[plan9fans@ntlworld.nospam.com]

Hi,

My all-time favorite Unix story, lifted from
http://cm.bell-labs.com/cm/cs/who/dmr/hist.html

Although the multiple-process idea slipped in very easily indeed,
there were some aftereffects that weren't anticipated.  The most
memorable of these became evident soon after the new system came up
and apparently worked.  In the midst of our jubilation, it was
discovered that the chdir (change current directory) command had
stopped working.  There was much reading of code and anxious
introspection about how the addition of fork could have broken the
chdir call.  Finally the truth dawned: in the old system chdir was an
ordinary command; it adjusted the current directory of the (unique)
process attached to the terminal.  Under the new system, the chdir
command correctly changed the current directory of the process created
to execute it, but this process promptly terminated and had no effect
whatsoever on its parent shell!  It was necessary to make chdir a
special command, executed internally within the shell.  It turns out
that several command-like functions have the same property, for
example login.


-Steve