RbConfig

Presents the configuration¹ for the current Ruby installation.

irb --simple-prompt -r -rbconfig

Requires the rbconfig module in an irb session

RbConfig::CONFIG['bindir']
=> "/home/vadim/.asdf/installs/ruby/3.0.0/bin"

Other useful keys in the CONFIG hash:

• rubylibdir - Ruby standard library
• bindir - Ruby command-line tools
• archdir - Architecture specific extensions and libraries (compiled, binary files)
• sitedir - Your own or third-party extensions and libraries (written in Ruby)
• vendordir - Third party extensions and libraries (written in Ruby)
• sitelibdir - Your own Ruby language extensions (written in Ruby)
• sitearchdir - Your own Ruby language extensions (written in C)