2.25: I deleted libc.a by accident --- how do I recover?

You can recover from this without rebooting or reinstalling, if you
have another copy of libc.a available that is also named "libc.a".  If
you moved libc.a to a different directory, you're in luck -- do the
following:

export LIBPATH=/other/directory


And your future commands will work.  But if you renamed libc.a, this
won't do it.  If you have an NFS mounted directory somewhere, you can
put libc.a on the that host, and point LIBPATH to that directory as
shown above.

Failing that, turn off your machine, reboot off floppies or other
media, and get a root shell.  I don't think you should do "getrootfs"
as you usually do when accessing the root vg this way -- AIX may start
looking for libc.a on the disk, and you'll just run into the same
problem.  So do an importvg, varyonvg, and then mount /usr somewhere,
then manually move libc.a back or copy in a new one from floppy.