"Mac has many enhancements to Unix in the area of files. Ignoring the whole resource fork thing which is not used much anymore, there are:
You can be denied operations on a file because of Unix permissions, ACLs or file flags.
- the standard Unix permissions ugo rwx and so on. Normal Unix tools apply.
- ACLs, viewable with
ls -le and changeable with
chmod [ -a | +a | =a ].
- file flags viewable with
ls -lO and changeable with
- extended attributes, viewable with
ls -l@ (attribute keys only) and changeable with
xattr. (Note that there is no man page for
xattr, but it's a simple program described with
To fully unlock a file:
sudo chmod -N ugo+rw somefile # Remove ACLs and set allow everyone read-write permission
sudo chflags nouchg somefile
Note that if
ls -lO shows that the
schg flag is set, you have to get into single-user mode to unset it. I'm not going to get into that here as there are bigger questions about why the file has that flag set and why you are trying to mess with it and what the consequences will be."