How to use watch command with a piped chain of commands/programs

watch 'command | othertool | yet-another-tool'

watch -n 1 "ls -lrt | tail -n20; date"

let's you pipe and run in a row.

If you would like to list all files in subdirectories too, you can use find command with exec option.

watch will update every 30 seconds and find will search for all *.log files in current dir (subdirs included) and will print filenames and their last 10 line:

watch -n30 'find . -name "*.log" -print -exec tail -n10 {} \; '