Monitor a set of files for changes and execute a command on them when they do

Question

The (command line) interface I have in mind is like so:

watching FILE+ do COMMAND [ARGS] (and COMMAND [ARGS])*

Where any occurrence of \"

Answer 1

You can use entr, e.g.

ls foo.txt bar.txt | entr sh -c 'rsync -vuar *.txt somewhere.com:. && echo Updated'

Unfortunately you can't check which file has been changed, but using rsync -u will automatically skip files which haven't been changed.

Here is the second example:

ls foo.c | entr sh -c 'gcc foo.c && ./a.out'

or simply use make, e.g.

ls -d * | entr sh -c 'make && make test'

To watch the directory for changes, use -d parameter wrapped inside a shell loop, e.g.:

while true; do find path/ | entr -d do_stuff; done