Updating System files

Question

Created Jun ’20

Replies 3

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I guess this is appropriate here since Big Sur is still in development

Yesterday I created a new APFS partition with macOS Big Sur. I usually edit some files in /System/Library files to tweak my home setup to my liking, including some display settings. However the steps I usually take to be able to edit these files no longer work.

These steps were:

Boot the Mac in recovery mode and go to the terminal,
Here I disable SIP using csrutil disable,
Reboot back in to Recovery Mode, open the terminal again
Remount the disk with write permissions using mount -uw /
Make the edits

However step 4 no longer seems to work on Big Sur as I am getting an error:

Code Block mount_apfs: volume could not be mounted: Permission denied
mount: / failed with 66

Is there another way to mount the file system with write permissions?

Answered by Developer Tools Engineer in 613832022

The system volume is now read-only so you should seek to avoid modifying system files.

Boost

Answer 1

nbelzer OP

Jun ’20

For those with a similar question, I found a similar post which is more active here.

2

Answer 2

Developer Tools Engineer OP

Apple

Jun ’20

Accepted Answer

The system volume is now read-only so you should seek to avoid modifying system files.

0

Answer 3

JustACleverKid OP

2d

I would like to detail a reliable method for modifying the /System folder on macOS Sonoma/Sequoia. this is not intended behavior since you aren’t supposed to be able to modify it, however it works pretty well. The TL;DR is you need to do 5 things:

Enable the root user using Directory Utility if not already done so.
Disable system integrity protection from recovery mode terminal (csrutil disable && csrutil authenticated-root disable)
Log-in as root
Mount the system data partition to a folder && make changes to it
Bless the volume as a startup snapshot and reboot.

(optional) 6. Re-enable SIP in recovery mode. I got the instructions from here: https://sites.google.com/view/delete-system-apps/home?authuser=1#h.203841rgwe44

0