This is an original planning guide. It is not a vendor manual, an official standard, or legal advice. Example addresses use documentation ranges. Review every command before you paste it.
What this hour is for
diskutil lists and can erase. The builder drafts a command. It does not run it. The first draft is a list. An erase names a disk identifier you read from that list, and that identifier is not the boot disk.
The Mac is one you administer. An erase destroys the volume. Do not practice on a disk that holds the only copy. Do not run an erase during the reading.
APFS container and volume are different. Write which one you mean before a later command.
The change you can finish
Apply nothing while you are writing the note. When the lab window opens, it is one change on the host named in the ticket. Read the draft, then the host, then decide.
Rollback is the file, the package version, or the snapshot you saved first. You do not invent a rollback after the only copy is gone.
- Draft a list.
- Identify the boot disk and exclude it.
- If an erase is a later ticket, name the other disk.
- Confirm a copy exists.
- Do not erase during the reading.
- Stop.
Mistakes that outlive the command
Managing Disks on macOS with diskutil goes wrong in a small set of ways. The list is here so the ticket can forbid them before the window.
- The boot disk erased.
- An erase during the reading.
- The only copy destroyed.
- A Mac you do not administer.
- Container and volume mixed up.
Decisions to write down
One decision for Managing Disks on macOS with diskutil: The first draft is a list. The boot disk is excluded. A copy exists before any later erase. Nothing was erased. And the Mac is yours.
Checks before you call it done
Confirm this before you call the change done: The boot disk is named and excluded. Any other disk is written. No erase was run. A copy is named if an erase is planned later. And the Mac is yours. If one of those fails, stop.
# List first.
# Do not erase the boot disk.
# Do not erase during the reading.
# A Mac you administer.Before you leave the host
Managing Disks on macOS with diskutil ends when the hostname in the prompt matches the hostname in the ticket. If it does not, you are on the wrong host. Stop. A command that succeeded on the wrong host is not progress.
The draft stays a draft until a person has read the names in it. A generator does not log into the host and does not know which disk is empty. You delete a line that names a host, a path, or an account you did not write down.
192.0.2.10/24, gateway 192.0.2.1, 198.51.100.0/24, 203.0.113.0/24, and 2001:db8::/32 are documentation. example.com is a documentation name. They belong in the note. They are not values you leave on a host because a draft included them.
prompt-for-this is a reminder that a secret is missing. It is not a password, a key, or a token you save in the ticket or in git. The real secret stays in the password store.
One change is the window. If two things move and the result is wrong, you will not know which one did it. The next change waits for its own page.
If the same step fails twice, stop for the day. The failure is the result. Adding a forum command beside a half-applied change produces a host nobody can rebuild. Restore the copy you took first.
A second person reads the hostname and the change aloud. If they cannot find them in the ticket, the note is not done. Silence is not agreement. Then leave the host alone.
This page is a planning guide. It is not a vendor manual, not an official standard, and not permission to touch a host you do not administer. You do not disable a firewall, AppArmor, or SELinux to make a check pass.
Tools for this guide
These tools run in the browser on this site. They do not log into your machines.
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