Enter entr


entr runs arbitrary commands when files change

In post (perl-c-ontinuous) I described a little script that monitors the filesystem for a change in a target file, and runs perl -c (the compilation check) over the file, just to make sure I don’t introduce syntax errors as I modify it.

I don’t know where, but I was later pointed towards entr, which generalizes this very idea in a program. It can control multiple files (the list is read in standard input) and do interesting things, like e.g. run a command only on a file that actually changed:

ls *.pl | entr perl -c /_

I did appreciate that the choice of the “file name placeholder” /_ has this explanation:

The special /_ argument (somewhat analogous to $_ in Perl) …

I’m always glad when I see this kind of references to Perl ❤️

entr seems to work out of the box on BSD, Linux and Mac OS, as well on the Linux Subsystem for Windows and Docker for Mac, although with a few restrictions (see the GitHub page).

All in all, it seems amazing and worth checking out! Thanks to whoever drove my attention to it!

Comments? Octodon, Twitter, GitHub, Reddit, or drop me a line!