Vendor binaries and the vendor/bin directory What is a vendor binary? Any command line script that a Composer package would like to pass along to a user who installs the package should be listed as a vendor binary. If a package contains other scripts that are not needed by the package users (like build or compile scripts) that code should not be listed as a vendor binary. How is it defined? It is defined by adding the bin key to a project's composer.json. It is specified as an array of files so multiple binaries can be added for any given project. {
    "bin": ["bin/my-script", "bin/my-other-script"]
} What does defining a vendor binary in composer.json do? It instructs Composer to install the package's binaries to vendor/bin for any project that depends on that project. This is a convenient way to expose useful scripts that would otherwise be hidden deep in the vendor/ directory. What happens when Composer is run on a composer.json that defines vendor binaries? For the binaries that a package defines directly, nothing happens. What happens when Composer is run on a composer.json that has dependencies with vendor binaries listed? Composer looks for the binaries defined in all of the dependencies. A proxy file (or two on Windows/WSL) is created from each dependency's binaries to vendor/bin. Say package my-vendor/project-a has binaries setup like this: {
    "name": "my-vendor/project-a",
    "bin": ["bin/project-a-bin"]
} Running composer install for this composer.json will not do anything with bin/project-a-bin. Say project my-vendor/project-b has requirements setup like this: {
    "name": "my-vendor/project-b",
    "require": {
        "my-vendor/project-a": "*"
    }
} Running composer install for this composer.json will look at all of project-a's binaries and install them to vendor/bin. In this case, Composer will make vendor/my-vendor/project-a/bin/project-a-bin available as vendor/bin/project-a-bin. Finding the Composer autoloader from a binary As of Composer 2.2, a new $_composer_autoload_path global variable is defined by the bin proxy file, so that when your binary gets executed it can use it to easily locate the project's autoloader. This global will not be available however when running binaries defined by the root package itself, so you need to have a fallback in place. This can look like this for example: <?php

include $_composer_autoload_path ?? __DIR__ . '/../vendor/autoload.php'; If you want to rely on this in your package you should however make sure to also require "composer-runtime-api": "^2.2" to ensure that the package gets installed with a Composer version supporting the feature. Finding the Composer bin-dir from a binary As of Composer 2.2.2, a new $_composer_bin_dir global variable is defined by the bin proxy file, so that when your binary gets executed it can use it to easily locate the project's Composer bin directory. For non-PHP binaries, as of Composer 2.2.6, the bin proxy sets a COMPOSER_RUNTIME_BIN_DIR environment variable. This global variable will not be available however when running binaries defined by the root package itself, so you need to have a fallback in place. This can look like this for example: <?php

$binDir = $_composer_bin_dir ?? __DIR__ . '/../vendor/bin'; #!/bin/bash

if [[ -z "$COMPOSER_RUNTIME_BIN_DIR" ]]; then
  BIN_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
else
  BIN_DIR="$COMPOSER_RUNTIME_BIN_DIR"
fi If you want to rely on this in your package you should however make sure to also require "composer-runtime-api": "^2.2.2" to ensure that the package gets installed with a Composer version supporting the feature. What about Windows and .bat files? Packages managed entirely by Composer do not need to contain any .bat files for Windows compatibility. Composer handles installation of binaries in a special way when run in a Windows environment:  A .bat file is generated automatically to reference the binary A Unix-style proxy file with the same name as the binary is also generated, which is useful for WSL, Linux VMs, etc.  Packages that need to support workflows that may not include Composer are welcome to maintain custom .bat files. In this case, the package should not list the .bat file as a binary as it is not needed. Can vendor binaries be installed somewhere other than vendor/bin? Yes, there are two ways an alternate vendor binary location can be specified:  Setting the bin-dir configuration setting in composer.json
 Setting the environment variable COMPOSER_BIN_DIR
  An example of the former looks like this: {
    "config": {
        "bin-dir": "scripts"
    }
} Running composer install for this composer.json will result in all of the vendor binaries being installed in scripts/ instead of vendor/bin/. You can set bin-dir to ./ to put binaries in your project root.

    
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