Inject changed file into command

[remy]

Allows users to programmatically use $FILE (or $EVENT) in their commands.

Such as:

watchy -w lib -- say "\$FILE changed"

Note that we escape the $FILE env value otherwise it gets evaluated immediately.

(Please excuse the typo in the actual commit, and the unsolicited PR!)

[remy]

It also means you can do things like this:

watchy -w styles -- "lessc \$FILE | autoprefixer -o .tmp/styles/\${\$(basename \$FILE)%.*}.css"

Which might look a little nuts, but can take the .less file that actually changed and then only process that changed file.

[caseywebdev]

This already works, no?

~ FOO=bar watchy -w . -- 'echo $FOO'
[watchy] echo $FOO Spawning...
bar
[watchy] echo $FOO Exited cleanly

[remy]

No, $FOO is a static env value that you're setting when you run watchy for the first time.

What $FILE is, is the full path of the file that triggered the event (that Chokidar passes to your all event handler). So this $FILE value will change depending on what caused the change.

[caseywebdev]

Ahh, I see what you mean. That sounds like a nice feature, thanks!

[tschaub]

I'm seeing a failure with 0.5.5 that goes away when downgrading to 0.5.4:

env: node: No such file or directory

I'm running watchy as part of a Makefile target that essentially looks like this:

watchy --watch src -- make dist

And the dist target runs browserify. Everything works at 0.5.4. When I include this change, the task fails. I'll dig a bit more to see if I can come up with a simpler test case.

[tschaub]

I think you want to copy everything from process.env first (and then add your EVENT and FILE - ideally only if they don't already exist).

[tschaub]

Proposed fix in #9.