How pkgx Works: A Conceptual Overview

How pkgx Works: A Conceptual Overview

Everything pkgx does involves initially creating package environment. It then either runs commands inside those environments or injects those environments into your running shell.

A command like:

pkgx node start

Is in fact implicitly:

pkgx +node node start

Which more precisely† is in fact:

pkgx +nodejs.org node start

† see disambiguation

The +pkg syntax creates the package environment that node start is then run within.

In fact you can see that env if you invoke pkgx raw:

$ pkgx +node
SSL_CERT_FILE=~/.pkgx/curl.se/ca-certs/v2023.5.30/ssl/cert.pem
PATH=~/.pkgx/unicode.org/v71.1.0/bin:~/.pkgx/unicode.org/v71.1.0/sbin:~/.pkgx/openssl.org/v1.1.1u/bin:~/.pkgx/nodejs.org/v20.5.0/bin
MANPATH=~/.pkgx/unicode.org/v71.1.0/share/man:~/.pkgx/zlib.net/v1.2.13/share/man:~/.pkgx/nodejs.org/v20.5.0/share/man:/usr/share/man
PKG_CONFIG_PATH=~/.pkgx/unicode.org/v71.1.0/lib/pkgconfig:~/.pkgx/openssl.org/v1.1.1u/lib/pkgconfig:~/.pkgx/zlib.net/v1.2.13/lib/pkgconfig
LIBRARY_PATH=~/.pkgx/unicode.org/v71.1.0/lib:~/.pkgx/openssl.org/v1.1.1u/lib:~/.pkgx/zlib.net/v1.2.13/lib
LD_LIBRARY_PATH=~/.pkgx/unicode.org/v71.1.0/lib:~/.pkgx/openssl.org/v1.1.1u/lib:~/.pkgx/zlib.net/v1.2.13/lib
CPATH=~/.pkgx/unicode.org/v71.1.0/include:~/.pkgx/openssl.org/v1.1.1u/include:~/.pkgx/zlib.net/v1.2.13/include:~/.pkgx/nodejs.org/v20.5.0/include
XDG_DATA_DIRS=~/.pkgx/unicode.org/v71.1.0/share:~/.pkgx/zlib.net/v1.2.13/share:~/.pkgx/nodejs.org/v20.5.0/share
DYLD_FALLBACK_LIBRARY_PATH=~/.pkgx/unicode.org/v71.1.0/lib:~/.pkgx/openssl.org/v1.1.1u/lib:~/.pkgx/zlib.net/v1.2.13/lib

This is a composable primitive, and is used by our shellcode, eg. env +node is basically just:

$ eval "$(pkgx +node)"

$ node --version
Node.js v20.5.0

And thus you could imagine pkgx npm start to be:

env "$(pkgx +node)" npm start