How do I repair permissions and rebuild the cache in Yosemite to Catalina?

[Hervé]

It's required after any kext addition, removal or modification, whether in /S/L/E or in /L/E.

 

To repair permissions, type the following Terminal commands:

sudo chmod -Rf 755 /S*/L*/E*
sudo chmod -Rf 755 /L*/E*
sudo chown -Rf 0:0 /S*/L*/E*
sudo chown -Rf 0:0 /L*/E*

`

To rebuild kextcache and prelinked kernel, type the following Terminal command:

sudo touch -f /S*/L*/E*
sudo touch -f /L*/E*
sudo kextcache -Boot -U /

`

Sometimes, the system returns an error message about not being able to modify/rebuild the cache and/or the prelinked kernel. In this case, the existing cache and prelinked kernel can be deleted using the following Terminal commands:

sudo rm -Rf /S*/L*/PrelinkedKernels
sudo rm -Rf /S*/L*/Caches/com.apple.kext.caches

The cache and prelinked kernel can then be rebuilt using the above touch and kextcache commands.

[Hervé]

For Mojave and lCatalina, use the following kextcache command:

sudo kextcache -i /

 

 

For Catalina, system's folder lock-out must be lifted before anything can be applied. Use the following commands to that effect:

sudo mount -uw /
sudo killall finder