$ su -c "yum --merge-conf update squid"
...
Dependencias resueltas
=========================================================================================
 Paquete             Arquitectura         Versión                   Repositorio    Tamaño
=========================================================================================
	 Actualizando:
 squid               x86_64               7:3.1.8-1.fc13               updates     1.6 M

 Resumen de la transacción
=========================================================================================
 Upgrade       1 Package(s)

 Tamaño total de la descarga: 1.6 M
 Está de acuerdo [s/N]:
...
 Ejecutando transacción
 Actualizando   : 7:squid-3.1.8-1.fc13.x86_64                                         1/2 
	  warning: /etc/squid/squid.conf created as /etc/squid/squid.conf.rpmnew
 Limpieza       : 7:squid-3.1.1-4.fc13.x86_64                                         2/2 

	   Package squid: merging configuration for file "/etc/squid/squid.conf":
	   By default, RPM would keep your local version and rename the new one to /etc/squid/squid.conf.rpmnew
	   What do you want to do ?
	   - diff the two versions (d)
	   - do the default RPM action (q)
	   - install the package's version (i)
	   - merge interactively with vim (v)
	   - background this process and examine manually (z)
	  Your answer ?  v