just is a handy way to save and run commands.
Commands are stored in a file called justfile with syntax inspired by make:
```make test-all: build ./test --all
test TEST: build ./test --test {{TEST}}
build: cc *.c -o main ```
just produces detailed error messages and avoids make's idiosyncrasies, so debugging a justfile is easier and less suprising than debugging a makefile.
If you need help with just please feel free to send me an email. Feature requests and bug reports are also always welcome!
just should run on any system with a reasonable sh and can be installed with cargo, the rust language package manager:
cargo install just~/.cargo/bin to your PATHOptionally, you can also alias j=just for lighting fast command running.
Once just is working, create a file called justfile in the root of your project and start adding recipes to it.
Recipes look like this:
```make recipe-name: echo 'This is a recipe!'
another-recipe: @echo 'Another recipe.' ```
Running just with no arguments runs the first recipe in the justfile:
sh
$ just
echo 'This is a recipe!'
This is a recipe!
When you invoke just it looks for a justfile in the current directory and upwards, so you can invoke just from any subdirectory of your project.
One or more arguments specify the recipes to run:
sh
$ just another-recipe
Another recipe.
just prints each command to standard error before running it, which is why echo 'This is a recipe!' was printed. Lines starting with @ will not be printed which is whyc echo 'Another recipe.' was not. printed.
Recipes stop running if a command fails. Here cargo publish will only run if cargo test succeeds:
make
publish:
cargo test
# tests passed, time to publish!
cargo publish
Recipes can depend on other recipes. Here the test recipe depends on the build recipe, so build will run before test:
```make build: cc main.c foo.c bar.c -o main
test: build ./test
sloc:
@echo "wc -l *.c lines of code"
```
sh
$ just test
cc main.c foo.c bar.c -o main
./test
testing... all tests passed!
Recipes without dependencies will run in the order they're given on the command line:
sh
$ just build sloc
cc main.c foo.c bar.c -o main
1337 lines of code
Dependencies will always run first, even if they are passed after a recipe that depends on them:
sh
$ just test build
cc main.c foo.c bar.c -o main
./test
testing... all tests passed!
Assignment, strings, concatination, and substitution with {{...}} are supported:
```make version = "0.2.7" tardir = "awesomesauce-" + version tarball = tardir + ".tar.gz"
publish: rm -f {{tarball}} mkdir {{tardir}} cp README.md *.c {{tardir}} tar zcvf {{tarball}} {{tardir}} scp {{tarball}} me@server.com:release/ rm -rf {{tarball}} {{tardir}} ```
Recipes may take arguments. Here recipe build takes an argument called target:
make
build target:
@echo 'Building {{target}}...'
cd {{target}} && make
Only one recipe that takes arguments may given on the command line, and other recipes may not depend on it. To pass arguments put them after the recipe name:
sh
$ just build my-awesome-project
Building my-awesome-project...
cd my-awesome-project && make
Variables can be exported to recipes as environment variables:
```make export RUST_BACKTRACE = "1"
test: # will print a stack trace if it crashes cargo test ```
Variables can also be overridden from the command line:
```make os = "linux"
test: build ./test --test {{os}}
build: ./build {{os}} ```
sh
$ just
./build linux
./test --test linux
You can pass any number of arguments of the form NAME=VALUE before recipes:
sh
$ just os=plan9
./build plan9
./test --test plan9
Or you can use the --set flag:
sh
$ just --set os bsd
./build bsd
./test --test bsd
Backticks can be used to store the result of commands:
``make
localhost =dumpinterfaces | cut -d: -f2 | sed 's/\/.*//' | sed 's/ //g'`
serve: ./serve {{localhost}} 8080 ```
Recipes that start with a #! are executed as scripts, so you can write recipes in other languages:
```make polyglot: python js perl sh ruby
python: #!/usr/bin/env python3 print('Hello from python!')
js: #!/usr/bin/env node console.log('Greetings from JavaScript!')
perl: #!/usr/bin/env perl print "Larry Wall says Hi!\n";
sh: #!/usr/bin/env sh hello='Yo' echo "$hello from a shell script!"
ruby: #!/usr/bin/env ruby puts "Hello from ruby!" ```
sh
$ just polyglot
Hello from python!
Greetings from JavaScript!
Larry Wall says Hi!
Yo from a shell script!
Hello from ruby!
just also supports a number of useful command line options for listing, dumping, and debugging recipes and variable:
sh
$ just --list
js perl polyglot python ruby
$ just --show perl
perl:
#!/usr/bin/env perl
print "Larry Wall says Hi!\n";
$ just --show polyglot
polyglot: python js perl sh ruby
Run just --help to see all the options.
justfile syntax is close enough to make that you may want to tell your editor to use make syntax hilighting for just.
For vim, you can put the following in ~/.vim/filetype.vim:
```vimscript if exists("didloadfiletypes") finish endif
augroup filetypedetect au BufNewFile,BufRead justfile setf make augroup END ```
Feel free to send me the commands necessary to get syntax hilighting working in your editor of choice so that I may include them here.
A description of the grammar of justfiles can be found in grammar.md.
Before just was a bloated rust program it was a tiny shell script that called make. If you can't or would rather not rust you can find the old version in extras/just.sh.
If you want some commands to be available everwhere, put them in ~/.justfile and add the following to your shell's initialization file:
sh
alias .j='just --justfile ~/.justfile --working-directory ~'
Or, if you'd rather they run in the current directory:
sh
alias .j='just --justfile ~/.justfile --working-directory .'
just is a trivial program, but I personally find it very useful to write a justfile for almost every project, big or small.
On a big project with multiple contributers, it's very useful to have a file with all the commands needed to work on the project close at hand.
There are probably different commands to test, build, lint, deploy, and the like, and having them all in one place is useful and cuts down on the time you have to spend telling people which commands to run and how to type them.
And, with an easy place to put commands, it's likely that you'll come up with other useful things which are part of the project's collective wisdom, but which aren't written down anywhere, like the arcane commands needed for some part of your revision control workflow, install all your project's dependencies, or all the random flags you might need to pass to the build system.
Some ideas for recipes:
Even for small, personal projects it's nice to be able to remember commands by name instead of ^Reverse searching your shell history, and it's a huge boon to be able to go into an old project written in a random language with a mysterious build system and know that all the commands you need to do whatever you need to do are in the justfile, and that if you type just something useful (or at least interesting!) will probably happen.
Anyways, I think that's about it for this incredibly long-winded README.
I hope you enjoy using just and find great success and satisfaction in all your computational endeavors!
😸