"This -- is wrong tool. Never use this."

Today, my life is devoted to cleaning up after an old automated daily backup script that included a line like this:

tar cpf - . | (cd /mount/subdir; tar xpf -)

Guess what happens when /mount/subdir doesn’t exist? “Hey, why are all these files truncated to some multiple of 512 bytes in size? And why are they now owned by root?”