$ less /opt/puppetlabs/bin/bolt 

#!/bin/sh

# avoid influences from already pre-configured other ruby environments
env \
  -u GEM_HOME \
  -u GEM_PATH \
  -u DLN_LIBRARY_PATH \
  -u RUBYLIB \
  -u RUBYLIB_PREFIX \
  -u RUBYOPT \
  -u RUBYPATH \
  -u RUBYSHELL \
  -u LD_LIBRARY_PATH \
  -u LD_PRELOAD \
  BOLT_ORIG_GEM_PATH="$GEM_PATH" \
  BOLT_ORIG_GEM_HOME="$GEM_HOME" \
  BOLT_ORIG_RUBYLIB="$RUBYLIB" \
  BOLT_ORIG_RUBYLIB_PREFIX="$RUBYLIB_PREFIX" \
  BOLT_ORIG_RUBYOPT="$RUBYOPT" \
  BOLT_ORIG_RUBYPATH="$RUBYPATH" \
  BOLT_ORIG_RUBYSHELL="$RUBYSHELL" \
  /opt/puppetlabs/bolt/bin/bolt "$@"