lost sysread

[Ray Andrews <rayandrews@xxxxxxxxxxx>]

    Any ideas?
      
      
      0 /aWorking/Zsh/Source/Wk 2 % . test1; print -r -- $(( srand32()
      ))
      srand32:4: command not found: sysread
      4
      
      0 /aWorking/Zsh/Source/Wk 2 % exit
      
      0 /aWorking/Zsh/Source/Wk 1 % . test1; print -r -- $(( srand32()
      ))
      3551593729
      
      0 /aWorking/Zsh/Source/Wk 1 % zsh -f
      b6-12-Deb12b# . test1; print -r -- $(( srand32() ))
      srand32:4: command not found: sysread
      4
      b6-12-Deb12b# exit
      
      0 /aWorking/Zsh/Source/Wk 1 % . test1; print -r -- $(( srand32()
      ))
      2230494374
      
      ... for some unknown reason one of my open shells can find sysread
      while others can't.  I use hibernate, so the OK shell has been
      open for far too long to digress as to which commands might have
      put it into a friendly mood as to sysread.  How on earth do I
      figure this out?  Printing out all my variables, there's dozens of
      differences, but there always are.  Any hot prospects? I can't
      think where I'd even begin.  How can a builtin ever not be found? 
      I know sometimes one 'level' of command can mask another, like a
      function 'sysread' might mask the builtin, but that's not the case
      here.  It's not disabled.  Nothing else seems to be broken or
      missing.  No idea.