Comparison with casey/just

run and just were written to accomplish, in essence, the same task of managing project-specific commands. Here is a breakdown of the main differences between the two command runners:

Disclaimers:

• I have not actually used just. This feature breakdown is based solely on the features listed in its documentation.
• This comparison is currently incomplete. Expect more headings to be added in the future.

Command execution

just always delegates script execution to an external shell. By default, each line of a recipe is executed by a individual sh instances, but a shell an be supplied for an entire recipe by placing a shebang #!/bin/sh line at the start of the recipe, or per-Justfile with a setting set shell := /bin/sh.

run, by default, tries to execute scripts itself, and provide output while doing so. It can be instructed to delegate to an external shell in the script header [script] /bin/sh or a file-wide option ::default-shell /bin/sh.

For both tools, this allows recipes/scripts to be written in any language, not just shell language.

Variables, positional parameters, and substitution

just allows variables to be defined at the top of a Justfile, which are evaluated before the recipe is executed and can be substituted into a recipe. Recipes can also define positional parameters build TARGET: that can be substituted in the same way. Variable substitutions are done with double curly braces cc -o {{TARGET}} {{TARGET}}.c, and positional parameters are passed on the command-line in the same way as a recipe target just build my-target.

run does not have the same concept of variables or script-specified positional parameters. These designs are handled by the shell language instead. Positional parameters are passed on the command-line separated from the main command by a --: run target -- argument, and can be read by the script using $1, $2, etc. parameter substitutions.