How to check KiCAD symbol library against KLC (KiCAD library conventions)

First, clonekicad-library-utils using

git clone https://gitlab.com/kicad/libraries/kicad-library-utils.git

Then, run the check script against your library using

~/kicad-library-utils/klc-check/check_symbol.py MyLibrary.kicad_sym -vv

You might need to adjust the path to kicad-library-utils accordingly.

This will provide colored output on the command line such as

Checking symbol 'Analog_Switch:FSA3157L6X':
Checking symbol 'Analog_Switch:NC7SB3157P6X':
  Violating S3.1
    Origin is centered on the middle of the symbol
    Symbol unit 1 not centered on origin
     - Center calculated @ (0, -112)
  Violating S3.6
    Pin name position offset
    Pin offset outside allowed range
     - Pin offset (5) should not be below 20mils