Justfile Cheat Sheet

#!/usr/bin/env just --justfile

# hello is recipe's name
hello:
  echo "Hello World!"

default: lint build test

# default recipe to display help information
default:
  @just --list

# default recipe with [default] attribute
[default]
hello:
   echo hello

# **if no default recipe, first recipe will be default**

alias t := test
alias c := check

set shell := ["zsh", "-cu"] 
#set shell := ["bun", "exec"] 

set dotenv-required

set dotenv-load := true

serv: 
   echo "$DATABASE_ADDRESS from .env"

set positional-arguments := true
foo:
  echo $0
  echo $1

string-with-tab := "\t"
string-with-newline := "\n"
escapes := '\t\n\r\"\\'
shell-expanded-path := x'~/${FOO}/${BAR}'
message := f'hello {{name}}'

# this string will evaluate to \`foo\nbar\n\`
x := '''
  foo
  bar
'''

- uses: extractions/setup-just@v1
  with:
    just-version: 1.45.0

# load bar/justfile, bar/.justfile, bar.just
mod bar

# include the contents of another justfile
import 'foo/bar.just'

filter PATTERN:
   echo "{{PATTERN}}"

# param with default value
email address='master@example.com':
   echo "{{address}}"

# param with validation pattern
[arg('n', pattern='\d+')]
double n:
  echo $(({{n}} * 2))

# param with expression
test triple=(arch() + "-unknown-unknown"):
  ./test "{{triple}}"

# variadic param: '+' aceept one or more values
[doc('Backup files')]
backup +FILES:
  scp {{FILES}} me@example.com

# variadic param with *: zero or more values
commit MESSAGE *FLAGS:
  git commit {{FLAGS}} -m "{{MESSAGE}}"

# recipe param as env variable with $ sign
hello $name:
   echo $name

# execution sequence:  a -> b -> c -> d 
b: a && c d

# execute recipe 'a'  around
b:
  echo 'B start!'
  just a
  echo 'B end!'

# depend with params by expression
default: (build "main")

build target:
  @echo 'Building {{target}}...'

hello:
  @ echo "command will not be echoed"
  - echo "ignore none-zero exit status and continue"

@hello2:
  echo "command will not be echoed"

# Invert command exit status by !  - shell feature
hello3:
  # if command succeeds(exit status is 0), exit just
  ! git branch | grep '* master'

bash-test:
    #!/usr/bin/env bash
    set -euxo pipefail
    hello='Yo'
    echo "$hello from bash!"

[script("bash")]
bash-test2:
    set -euxo pipefail
    hello='Yo'

[script('bun', 'run')]
[extension(".ts")]
bun-hello:
   let name: string = "Jackie"
   console.log(`Hello ${name}!`)

[script("duckdb", "-f")]
query:
   select version()
    echo "$hello from bash!"

test: _test-helper
  ./bin/test

# ommited from 'just --list'
_test-helper:
  ./bin/super-secret-test-helper-stuff

for recipe in \`just -f ~/.justfile --summary\`; do
  alias $recipe="just -f ~/.justfile -d. $recipe"
done

venv:
  [ -d .venv ] || uv venv

run: venv
  ./.venv/bin/python3 main.py

version := "0.2.7"
tardir  := "awesomesauce-" + version
tarball := tardir + ".tar.gz"
path := "a" / "b"  # join path
var1 := '' && 'goodbye'  # ''
var2 := 'hello' && 'goodbye'  # 'goodbye'
var3 := '' || 'goodbye'        # 'goodbye'
var4 := 'hello' || 'goodbye'  # 'hello'


test:
   echo "{{version}}"

# set/override variables from just command line
$ just --set version 1.1.0

export RUST_BACKTRACE := "1"

test:
    # will print a stack trace if it crashes
    cargo test

JAVA_HOME := \`jbang jdk home 11\`
#  backtick code block
stuff := \`\`\`
   foo="hello"
   echo $foo "world"
 \`\`\`

done BRANCH=\`git rev-parse --abbrev-ref HEAD\`:
  git checkout master

sloc:
    @echo "\`wc -l *.c\` lines of code"

# **backtick works anywhere:  string/variable/params**

hello name:
   echo "{{os()}}"
   echo "{{uppercase(name)}}"

# function categories
* System Information
* Environment Variables
* Justfile and Justfile Directory
* String Manipulation
* Path Manipulation

# String contact:  (key + ":" + value)

# regular expression match
fo := if "hi" =~ 'h.+' { "match" } else { "mismatch" }

test:
   if true; then echo 'True!'; fi
   for file in \`ls .\`; do echo $file; done
   while \`server-is-dead\`; do ping -c 1 server; done

foo bar:
  echo '{{ if bar == "bar" { "hello" } else { "bye" } }}'

# Each command line is executed by a new shell.
# If a command line failed, just will exit, \
# and subsequent command lines will not be executed.
change-working-dir:
   cd bar && pwd
   # multi-line construct - escape newline with slash
   if true; then \
        echo 'True!'; \
   fi

# justfile is case insensitive: Justfile, JUSTFILE etc
# justfile could be hidden:  '.justfile'
# Call recipe from sub dir:  \`~/app1/target>$ just build\`