Exactly how small is it? How big was the original log file? What does
file bla.log.gz say?
gzip bla.log will write
bla.log.gz and then, if that was successful, delete
gunzip blo.log.gz will write
bla.log and then delete
If something goes wrong during the
gzip command (say, it ran out of space, exceeded your quota, was killed by a signal, or the computer lost power), then you could easily end up with a partial or corrupted
bla.log.gz file -- but then the original
bla.log file should still be there.
And if you then run
gunzip bla.log.gz, you should get a prompt like:
gzip: bla.log already exists; do you wish to overwrite (y or n)?
It shouldn't have clobbered your original
bla.log file unless (a) you told it to (by using
gunzip -f or by anwering
y to the above prompt), or (b) it successfully generated
To answer your question, if
bla.log.gz consists of nothing more than a few zero bytes, you're not going to get anything useful out of it.