Files can be locked on OS X by going to the "Get Info" panel for the specific file and clicking the lock button.
I would need to remove locks from a shell script. What unix command can do that?
Unlock "Locked" flag on a folder recursivly
chflags -R nouchg /folder/path
Try chflags nouchg YOUR_FILE. To re-enable the lock, chflags uchg YOUR_FILE.
chflags nouchg YOUR_FILE
chflags uchg YOUR_FILE
If you've got xcode installed, /Developer/Tools/SetFile. To unlock:
/Developer/Tools/SetFile
% SetFile -a l <path>
To lock:
% SetFile -a L <path>
To query, you can use /Developer/Tools/GetFileInfo
/Developer/Tools/GetFileInfo