On hidden Files, especially Library

I published a book: “Packaging for Apple Administrators”

While writing on the next book “Automated Packaging for Apple Administrators”, I will keep publishing small side notes and excerpts. There is a nice gem for macOS Sierra in the last section, so keep reading.;)

Mac OS X has always hidden certain folders and files from the user. The more ‘UNIXey’ folders like /usr, /bin, and /etc were considered too confusing or even dangerous for most users and hidden away. Most users noticed this in OS X Lion when Apple started hiding the user’s Library. Messing with files in the Library can cause damage or data loss if a user does not know exactly what they are doing. Here is the summary on hidden and invisible files.

Dot Files

In UNIX, files or directories with a name beginning with ‘.‘ (period or dot) are considered hidden and will not be shown in a normal file list with ls. You can however easily list them with the option ls -a. Usually dot files are configuration files or folders.

When does Finder consider a File hidden?

Like the ls command Finder will not show files beginning with a ‘.‘ (period or dot). However, there is also an extra hidden flag that Finder will check to see wether it should hide a file. You can see this hidden flag in Terminal with the -O (capital o) option for ls

$ ls -lO 
drwx------+ user  staff  -        Downloads
drwx------@ user  staff  hidden   Library
drwx------+ user  staff  -        Movies

(I removed lines and columns to make the output more legible.)

You can also use the find command to show all files with the hidden flag:

$ find ~ -flags +hidden -print

Use the chflags command to set or unset the hiddenflag:

$ chflags nohidden ~/Library
$ chflags hidden ~/Library

Finder will show or hide the file or folder immediately.

Navigating to your hidden Library

When you click on Finder’s ‘Go’ Menu with the option key, Library will appear as an option.

You can also use Finder’s ‘Go to Folder…’ menu and enter ~/Library as the target. This is especially useful since you usually want to go to a subfolder of Library anyway. This panel supports tab-autocompletion like the shell. OS X 10.11 and earlier would autocomplete to the alphabetically first match so ~/Library/Pref would complete to ~/Library/PreferencePanes rather than ~/Library/Preferences. macOS Sierra will show a popup list if the completion is ambiguous. The keyboard shortcut for ‘Go to Folder…’ command-shift-G will also work in open and save panels.

If you are already in a Terminal window you can use the open command:

$ open ~/Library/

Show all hidden Files and Folders

macOS Sierra has added a great Finder keyboard shortcut to quickly show hidden files and folders. Command-Shift-. (dot or period) will quickly show all hidden files and a second time will re-hide them.

This keyboard shortcut has worked in open and save dialogs for a while already.

In older versions of OS X you have to open Terminal and run:

$ defaults write com.apple.Finder AppleShowAllFiles true
$ killall Finder

Change the true to false to switch it back.