Clobbered C library warning

[Operator]

The warning about changing the shared 'C' library from Ken Olum is right
on target.  We have run into his problem a bunch of times when attempting
to switch 'C' libs.  Here are a couple of things I have learned:

    1) NEVER use cp - it is dynamically linked and always gets mangled;
    2) You MAY be able to get away with using install - it just uses reads
       and writes, so the chances of overwriting some executing routine are
       small. You can try this if your needs demand it, but I wouldn't bet the
       farm on it.
    3) The following are statically linked, so they always work.  You can use
       them to avoid c/trashing your system when you are playing with the 
       dynamic 'C' library:
          tar - use this to move the library or to restore a good version from
                tape, etc;
          mv  - use this to overwrite the version you want to replace.
          sh  - you can shutdown to single-user mode, use mv or tar to replace
                the library, and then <cntl-D> back up to multi-usr mode.
          cd  - to get around.

To find out if a particular program is statically or dynamically linked,
use the ldd(1) command (not, however, that SUN in their infinite wisdom
made this dynamically linked, so ldd won't work if your 'C' lib is already
trashed).

Mark Hickey          Computervision Division
O/S Development      Prime Computer, Inc.
                     Bedford, MA     01730

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