GNU tar blocking factor, blocks, records and checkpoints

> Because tar operations may be long running, it can be useful to have feedback about progress during the operation.

For those running on a system that has SIGINFO (e.g., BSD, macOS?), hit ^T and you'll get a status report to stderr. ^T should work for various other utilities as well: dd, cp, ftp.

On those systems that do not have SIGINFO (Linux?), but are using bsdtar (libarchive), SIGUSR1 will do the same:

* https://github.com/libarchive/libarchive/search?q=SIGINFO

INFO isn't one of the mandatory POSIX signals:

* https://en.wikipedia.org/wiki/Signal_(IPC)#POSIX_signals

Tar is a convenient format for basic embedded data storage since it's easy to parse and you don't have to build custom tooling to prepare them. We'd store small pre-gzipped web resources in a tar file and send them out as is without needing onboard compression. The blocking factor puzzled me for a bit when I was trying to store a few hundred bytes and couldn't understand where the extra 10k was coming from. Sometimes you have to RTFM.