j

j is a handy way to run project-specific commands.

j looks upward from the current directory for a file called justfile and then runs make with that file as the makefile. j also sets the current working directory to where it found the justfile, so your commands are executed from the root of your project and not from whatever subdirectory you happen to be in.

With no arguments it runs the default recipe:

j

Adding one argument specifies the recipe:

j compile

Arguments after -- are exported as ARG0, ARG1, ..., ARGN, which can be used in the justfile. To run recipe compile and export ARG0=bar and ARG1=baz:

just compile -- bar baz

By way of example, the included justfile has a pinch of fanciful fluff.

getting j

J is distributed via cargo, rust's package manager.

1. Get cargo at rustup.rs
2. Run cargo install j
3. Add ~/.cargo/bin to your PATH

j depends on make to actually run commands, but hopefully if you're on a unix, make is already installed. If not, you can get it from friendly local package manager.