pw (view data passing through a pipe)

pw stands for Pipe Watch, a utility that continuously reads lines
of text from a pipe or pipe-like source, passes them through a FIFO
buffer, and maintains a display based on occasionally sampling the
contents of the FIFO buffer, with useful features such as triggering
and filtering.

pw can monitor anything that produces textual output. tail -f
/var/logfile, tcpdump, strace, ...