chflags

Change a file or folder’s flags.

Syntax 
      chflags [-fhvx] [-R [-H | -L | -P]] flags file-or-folder ...

Options
   -R      Recurse: Change the file flags of file-or-folder hierarchies rooted in the files
           instead of just the file-or-folder themselves.
           So if the given folder contains files or sub-folders, apply the change to them all.

           Beware of unintentionally matching the .. hard link to
           the parent directory when using wildcards like ".*".

   -R -H   Follow symbolic links on the command line
           by default Symbolic links within the tree are not followed.

   -R -L   All symbolic links are followed.

   -R -P   No symbolic links are followed. (default)

   -f      Do not display a diagnostic message if chflags could not modify the flags for file-or-folder, nor modify
           the exit status to reflect such failures.

   -h      If the file-or-folder is a symbolic link, change the file flags of the link itself rather than the file to which it points.

   -v      Cause chflags to be verbose, showing filenames as the flags are modified.
           If the -v option is specified more than once, the old and new flags of the file will also
           be printed, in octal notation.

   -x      Do not cross mount points.

The flags are specified as an octal number or a comma separated list of keywords.

             hidden           Set the hidden flag [Hide item from GUI]

Keywords and keyword aliases - Owner or Super-user only:

             opaque           Set the opaque flag 
             nodump           Set the nodump flag 
             uappnd, uappend  Set the user append-only flag
   uchg, uchange, uimmutable  Set the user immutable flag
             uunlnk, uunlink  Set the user undeletable flag

Keywords and keyword aliases - Super-user only:

             arch, archived   Set the archived flag
             sappnd, sappend  Set the system append-only flag
   schg, schange, simmutable  Set the system immutable flag
             sunlnk, sunlink  Set the system undeletable flag

The immutable flag makes the file/folder Locked/Protected and is equivalent to locking the file in Finder’s Show Info box.

Putting the letters no before an option causes the flag to be turned off.

  For example:
       uchg    Means the file cannot be changed
     nouchg    Means the file can be changed (immutable bit cleared)
        hidden  Will set the hidden flag
      nohidden  Will remove the hidden flag

In early versions of macOS locked/immutable files could not be deleted from the trashcan. In Mac OS X 10.1 and later locked files can easily be deleted by pressing press Shift-Option or Option key combination while emptying the Trash.

Symbolic links do not have flags, so unless the -H or -L option is set, chflags on a symbolic link always succeeds and has no effect. The -H, -L and -P options are ignored unless the -R option is specified. In addition, these options override each other and the command’s actions are determined by the last one specified.

The sappnd and schg flags can only be unset when the system is in single-user mode. chflags(2).

Use ls -lO to see the flags of existing files.

The return status is zero if the mode is successfully changed,and >0 if an error occurs.

Examples

Lock the folder "finance" against changes:

$ chflags uchg finance

Unlock the folder named "finance" and allow changes to all the contents:

$ chflags -R nouchg finance

Make the folder ~/Library visible (this was the default setting prior to OS X Lion):

$ chflags nohidden ~/Library

An alternative method to view the library is to use the 'Go' drop down menu in Finder and hold down the option key:

Hide the folder ~/Library from finder:

$ chflags hidden ~/Library

Make the file MyLogs.txt append-only:

$ chflags uappnd MyLogs.txt

Unlock your Documents directory and everything in it:

$ chflags -R nouchg ~/Documents

“Fifteen referees. I want fifteen referees to be at this fight because there ain’t no one man who can keep up with the pace I’m gonna set except me. There’s not a man alive who can whup me. I’m too fast. I’m too smart. I’m too pretty. I should be a postage stamp. That’s the only way I’ll ever get licked” ~ Muhammad Ali

Related macOS commands

Local man page: chflags - Command line help page on your local machine.
HT1526 - Empty the (locked) trash with chflags.
ln - Make links between files (hard links, symbolic links).
ls - List information about file(s).
setfile - Set attributes of HFS+ files.
xattr - Edit or remove extended file attributes, including 'Where From' website data.