Watchfile display given file. If there's any changes, rewrite it.
$ watchfile file.txt
# screen will be cleard, and cat that file from (1,1)
# and when you edit and save the file, watchfile will rewrite it.
$ brew tap Cj-bc/watchfile
$ brew install watchfile
when you use hoembrew, it might not work and say 'Permission denied.'
This is known big bug and this is caused because watchfile itself($(brew --prefix)/Cellar/watchfile//bin/watchfile) has no permission to execute.
I'm not sure why it's occured, but the easy solution is to run:
$ chmod 755 $(brew --prefix)/Cellar/watchfile/<version>/bin/watchfile
$ bpkg install Cj-bc/watchfile -g
$ git clone https://github.com/Cj-bc/watchfile.git
$ cd watchfile
$ mv watchfile.sh /usr/local/bin/watchfile