Macintosh Terminal Pocket Guide

Name

fsck_hfs — stdin  stdout  - file  -- opt  --help  --version

Synopsis

fsck_hfs [options] [devices]

The fsck_hfs command validates a Macintosh HFS-formatted disk partition and, if requested, repairs errors found on it. (Alternatively, you can run the diskutil command, or the graphical application Disk Utility in the Utilities folder.) In general, unmount a device before checking it, so no other programs are operating on it at the same time:

➜ sudo diskutil unmount /dev/disk1s2
➜ sudo fsck_hfs -f /dev/disk1s2
** /dev/rdisk1s2
** Checking Journaled HFS Plus volume.
** Checking Extents Overflow file.
** Checking Catalog file.
** Checking multi-linked files.
...

OS X includes more validation programs for other kinds of filesystems. Run man -k fsck to see a list.

Useful options

-f	Force a filesystem check, even if OS X says the filesystem doesn’t need it.
-n	Do not fix errors, just report them.
-y	Fix errors automatically (use only if you really know what you’re doing; if not, you can seriously mess up a filesystem).