Besides the main yosys executable, the Yosys distribution contains a set of additional helper programs.
The yosys-config tool (an auto-generated shell-script) can be used to query compiler options and other information needed for building loadable modules for Yosys. See Sec. Section 6 for details.
The yosys-filterlib tool is a small utility that can be used to strip or extract information from a Liberty file. See Sec. 9.3 for details.
This is a fork of ABC with a small set of custom modifications that have not yet been accepted upstream. Not all versions of Yosys work with all versions of ABC. So Yosys comes with its own yosys-abc to avoid compatibility issues between the two.