has checks presence of various command line tools on the PATH and reports their installed version.

Just install the has script, (there is no dependency apart from bash itself). From the command line, pass the list of commands you want to check as arguments to has, for example:

$ has node npm java git gradle
✓ node 22.17.0
✓ npm 11.5.1
✓ java 21.0.7
✓ git 2.50.1
✓ gradle 8.14.2

If everything is good has exits with status code 0. The exit status code reflects number of commands not found on your path.

$ has node go javac
✓ node 22.17.0
✓ go 1.24.5
✘ javac

And echo the status:

$ echo $?
1

has can be used in shell scripts to check presence of tool in very readable way

if has node
    then echo you have what it takes 🎉
fi

Pro Tip: the has in above command can be replaced with the entire curl command for to ensure portability of script → if curl -sL https://git.io/_has | bash -s node then ...

has is a single bash script that does it all. You can download the script and make it available on your $PATH. However, to make it even simpler, just follow one of these methods.

Just run the following:

brew install kdabir/tap/has

Just execute the following command in a terminal: it clones has repo and installs it into your path.

git clone https://github.com/kdabir/has.git && cd has && sudo make install

For a non-root installation:

git clone https://github.com/kdabir/has.git
cd has
make PREFIX=$HOME/.local install

To update just do a git fetch or make update followed by the appropriate make install command.

curl -sL https://git.io/_has > /usr/local/bin/has

curl -sL https://git.io/_has | sudo tee /usr/local/bin/has >/dev/null

These commands are safe to be called multiple times as well (to update has)

asdf plugin add has https://github.com/sylvainmetayer/asdf-has
asdf install has 1.4.0

If you are lazy, you can run has directly off the Internet as well:

curl -sL https://git.io/_has | bash -s git node npm
✓ git 2.50.1
✓ node 22.17.0
✓ npm 11.5.1

ProTip: if that's too much typing every time, setup an alias in your .bashrc/.zshrc file:

alias has="curl -sL https://git.io/_has | bash -s"

And use it

$ has git
✓ git 2.50.1
$ type has
has is aliased to `curl -sL https://git.io/_has | bash -s'

Let's say $ has foobar returns foobar not understood, because has may not have whitelisted foobar.

In such cases, pass HAS_ALLOW_UNSAFE=y has foobar. This should still check for existence of foobar and tries to detect version as well.

the value must exactly be y for it to work.

has looks for .hasrc file in the directory from where has command is issued. This file can contain commands that has will check for. List one command per line. Lines starting with # are treated as comments.

Following is example of .hasrc file:

# tools
git
curl

# interpreters
ruby
node

When has is run in directory containing this file, it produces:

$ has
✓ git 2.50.1
✓ curl 8.5.0
✓ ruby 3.4.1
✓ node 22.17.0

Also, CLI arguments passed to has are additive to .hasrc file. For example, in the same dir, if the following command is fired, has checks for both commands passed from cli args and provided in .hasrc file.

$ has java
✓ java 21.0.7
✓ git 2.50.1
✓ curl 8.5.0
✓ ruby 3.4.1
✓ node 22.17.0

Pro Tip: commit .hasrc file in root of your project. This can work as a quick check for confirming presence all command line tools required to build and run your project.

On machines that don't even have has installed, your project's .hasrc is honored by this command:

curl -sL https://git.io/_has | bash -s

take a look at .hasrc file for this repo.

here are some ways you can help:

1. Star the repo, write about it, spread the word
2. Update the documentation (including this README)
3. Adding support for more commands and features - see CONTRIBUTING.md