How to Change File Permissions on Mac (Get Info)

Every file on your Mac carries a small access list: who can open it, who can change it, who can’t touch it. When a folder refuses to open or an app claims “you don’t have permission”, that list is what’s in the way — and you can read and edit it from Finder’s Get Info window in under a minute.

Read the permissions on any file

1. Select the file or folder in Finder and press Cmd+I.
2. Scroll to Sharing & Permissions at the bottom and expand it if it’s collapsed.
3. Read the table: each row is a user or group — typically you, staff (regular users on this Mac), and everyone — with a privilege beside it.

The three privileges do what they say:

• Read & Write — open, edit, rename, delete.
• Read only — open and copy, but not change.
• No Access — can’t even open it. On folders you may also see Write only (Drop Box): others can put files in but can’t see what’s inside — it’s what makes the ~/Public/Drop Box folder work.

Change them

1. Click the padlock in the bottom-right corner of the Get Info window and authenticate with your password or Touch ID.
2. Click the privilege next to any user and pick the new level from the menu. The change applies immediately — there’s no Save button.
3. To grant access to a specific person, click + under the table and pick a user of this Mac; select a row and − removes it.
4. Made it worse? The gear menu offers Revert changes until you close the window — after that, undo means setting the values back by hand, so note what the table said before you start.

Fix a folder full of wrong permissions

Changing a folder’s permissions affects the folder itself — not the hundreds of files already inside it. After setting the folder the way you want, click the gear under the table and choose Apply to enclosed items…. That pushes the folder’s current permission set into everything inside, recursively. It’s the standard fix for an external drive or copied project folder where half the files open and half don’t. Two cautions: it can’t be undone in one step, and never run it on system folders — only on your own data.

The Terminal view, briefly

Permissions are Unix underneath, and sometimes Terminal is quicker for a single file:

# see current permissions first, so you can restore them
ls -l report.pdf
# -rw-r--r--  owner can edit, everyone else read-only
# make a file private to you
chmod 600 report.pdf
# undo: restore the common default shown above
chmod 644 report.pdf

Always run ls -l before chmod so you know what to put back. If a file won’t budge even with Read & Write — deletions blocked, edits refused — check the Locked checkbox in Get Info’s General section instead; a lock overrides permissions and has its own fix.

The external-drive special case

Files on an external drive that came from another Mac often show the wrong owner — every file belongs to “_unknown” or to an account that doesn’t exist here, and nothing opens. Before rewriting permissions file by file, use the switch built for exactly this: select the drive in Finder, press Cmd+I, unlock the padlock, and tick Ignore ownership on this volume at the bottom of Sharing & Permissions. macOS then treats everything on the drive as yours, no per-file surgery required. Untick the same box to undo it. (The checkbox only appears on external volumes — system disks always enforce ownership.) One caveat: don’t use it on a shared drive where you actually want per-user separation, since it removes exactly that.