Can't add SSH file to SD Card

Question

Yesterday I got a raspberry pi4 together with a micro SD Card which is preloaded with Raspberry PI OS (32-bit).

I don't have a separate keyboard or mouse but I do have a laptop (a Mac) and so I decided to go for a headless connection.

As per the instruction "If you want to enable SSH, all you need to do is to put a file called ssh in the /boot/ directory" I issued the commands "cd /Volumes/boot" and "touch shh" in Terminal which gave me to which I got the response "ssh: Read-only file system".

And ever since I've been trying to figure out how to get the micro SD card writable. Changing the lever on the SD card holder does not help nor does recreating the image using the Raspberry PI Imager.

Any idea what I need to do to get the micro SD card writable (or any other way to allow me to access the raspberry from my Mac ?

Update 08 Jan-21

Thanks for all these suggestions. See below the output.

1. Micro SD card is brand new (purchased at the rapsberry online webshop)
2. Micro SD card is inserted in SD card 'holder'
3. Switch on SD card holder is set to unlocked
4. SD card holder is inserted in stick that connects to Mac with a USB-C adapter
5. Ran "diskutil list" command:

% diskutil list
/dev/disk2 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:     FDisk_partition_scheme                        *63.9 GB    disk2
   1:             Windows_FAT_32 ⁨boot⁩                    268.4 MB   disk2s1
   2:                      Linux ⁨⁩                        3.7 GB     disk2s2
                    (free space)                         59.9 GB    -

6. Ran "ls -l | grep boot" command

% ls -l | grep boot
drwxrwxrwx@ 1 be022692  staff  3584 Dec  2 13:02 boot  

7. Ran Disk Utility[

To make sure I can write on the card I subsequently used Raspberry PI Imager app to put another OS on the card (LibreElec). See below output

1. Ran "diskutil list" command /dev/disk2 (external, physical): #: TYPE NAME SIZE IDENTIFIER 0: FDisk_partition_scheme *63.9 GB disk2 1: Windows_FAT_32 ⁨LIBREELEC⁩ 536.9 MB disk2s1 2: Linux ⁨⁩ 33.6 MB disk2s2 (free space) 63.3 GB -
2. Ran "ls -l | grep LIBREELEC command" drwxrwxrwx@ 1 be022692 staff 16384 Oct 24 18:05 LIBREELEC
3. Ran Disk Utility

In both instances the FAT folders "boot" and "LIBREELEC" are read-only so impossible to add files.

What would you suggest as best way forward ?

Answer 1

As per the instruction "If you want to enable SSH, all you need to do is to put a file called ssh in the /boot/ directory"

I'm hoping that's not literally what it says in the Foundation docs, because it is misleading if you are new to the whole deal. But if you aren't, it's understandable why someone would refer to it this way.

Filesystem partitions in linux (*nix generally, I'd think this includes MacOS) are "mounted" in a directory tree rooted at the "root" fs. There are two partitions on the card, the 2nd is the root fs, and when the system is running, the 1st partition is normally mounted at /boot.

However, if you stick the card in another computer you just see the two partitions and referring to "the /boot directory" doesn't make sense. I think on a Mac you can only read the first one anyway, but it should contain a few dozen files including kernel.img. That's where you want to put the ssh file.

Answer 2

I think there are two possibilities:

Case 1. Assuming your SD card is a relatively new one, I think you've done something wrong, somehow. Does your SD card have a wee switch on it to make the entire card RO? - or, maybe your Mac user doesn't have any privileges, - or, something else... On my Macs (Catalina, Mojave and High Sierra), I have no problem at all doing what you just said you weren't able to do.

Case 2. If the SD card has been around for a while - perhaps served as a storage device for another computer, camera, etc: It may be "worn out". It seems that a symptom of SD cards approaching end-of-life is that they go into read-only mode.

If your SD card is covered under case 2 above, you should make a backup, and retire the card ASAP. If your card is covered under case 1, please read on - here's some things to try:

How have you connected to the SD card? Have you removed it from the RPi & connected to your Mac via a USB "adapter"? What do you see in Disk Utility? Is it like this:

Please show us what you see in your Mac Terminal app when you enter:

% ls -l /Volumes | grep boot

It should be something like this:

drwxrwxrwx@ 1 seamus staff 3584 Jan 7 12:26 boot

---

EDIT - Additions:

1. diskutil list

seamus@Dung-Pro % diskutil list

... 

/dev/disk3 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:     FDisk_partition_scheme                        *31.9 GB    disk3
   1:             Windows_FAT_32 boot                    268.4 MB   disk3s1
   2:                      Linux                         31.6 GB    disk3s2

CONCLUSION: disk3s1 is a FAT32 partition

2. check permissions via ls -l in /Volumes/boot

seamus@Dung-Pro % cd /Volumes/boot
seamus@Dung-Pro boot % ls -l
total 91359
-rwxrwxrwx  1 seamus  staff    18693 Jan  8 00:45 COPYING.linux
-rwxrwxrwx  1 seamus  staff     1594 Jan  8 00:48 LICENCE.broadcom

...

-rwxrwxrwx  1 seamus  staff  3698056 Jan  8 00:47 start_x.elf

CONCLUSION: /Volumes/boot is 777 (see above), AND all files in /Volumes/boot are 777 (rwx for all)

3. create / touch the ssh file

seamus@Dung-Pro boot % touch ssh
seamus@Dung-Pro boot % ls -l | grep ssh
-rwxrwxrwx  1 seamus  staff        0 Jan  8 11:14 ssh

CONCLUSION: /Volumes/boot is writeable on my macOS Catalina 10.15.7 without privilege elevation (aka sudo). Ergo, your issue is either macOS-related, or your SD card is somehow faulty. I would suggest: 1. Try another SD card, 2. present your question to the Apple SE.

And by all means, do not hesitate to elaborate here (in further comments) on anything else you feel may be relevant.

Answer 3

I found the solution to my problem.

I was using a company-provided laptop and due to a change in policy in the first week of this year it's no longer possible/allowed to write data to direct-attached device.
That's why I was unable to get the "ssh" and "spa_supplicant.conf" files.
So I got myself a second-hand laptop with a standard set-up and in no time I got the SD card fully ready.

I owe you guys a big apology for wasting your time and goodwill :-(.

Answer 4

Your SD card has several partition on it. One is FAT partition, others might be ext4 which could be / (the root) which contains /boot, or /home parition, I don't know how they partitioned a card when it was "preloaded".

The FAT partition is mounted to /boot at runtime. You must put a file there. For reference, there is a config.txt file there, a bunch of *.dtb files, also files named kernel6, kernel7, kernel8 and so on - variants of linux kernel for different revisions of Raspberry Pi board. Put a file next to config.txt. macOS must be able to write to FAT.

I am surprised to read you had seen to see a a /boot folder which normally resided on an ext4 / (root) partition. I didn't knew macOS supports a Linux file system. Even it that, it is possible it supports it in read-only mode.