The macOS open Command

You can learn more about using Terminal and the shell on macOS in my my book: “macOS Terminal and Shell” — Thank you!

Most Terminal users will know that

$ open .

will open the current working directory in a Finder window. (You, dear wonderful reader, know this because you read my previous post on Terminal-Finder Interaction.)

However, the open command can do so much more.

Folders

Trivially, it cannot merely open the current working directory, but any path:

$ open ~/Library/Preferences
$ open /etc
$ open ../..

This can be used as a quick way to navigate to hidden directories.

You can also open multiple folders at once:

$ open ~/Documents ~/Desktop ~/Downloads
$ open ~/D*

To clean up, you can option-click any close button in a Finder window to close all Finder windows. Or you can use the keyboard short cut ⌘⌥W.

Files

open can also open files. In general you can think of open as the command line equivalent of double-clicking a file or folder in Finder.

$ open document.pdf

will open document.pdf in the current working directory with the default application for PDF files (usually Preview). You can use this against multiple files as well:

$ open ~/Desktop/Screen\ Shot\ *.png

will open all screenshot files (if any) in a viewer in the default application (Preview).

Applications

If you have changed the default application that handles a file type or want to override the default application, you can use the -a option:

$ open -a Preview ~/Desktop/Screen\ Shot\ *.png
$ open -a TextEdit web.html

You can specify just the name of an application or the full path, i.e. /Applications/Preview.app. If you need to be specific, you can also specify an application’s bundle identifier with -b com.apple.Preview.

If you want to open a document but keep the application and the new document window in the background, use the -g option.

$ open -g ~/Desktop/Screen\ Shot\ *.png

Text Editors

There are two interesting special cases for designating applications:

$ open -e helloworld.swift

will open a file with TextEdit.

$ open -t helloworld.swift

will open a file with the default application for text files (.txt file extensions) You can use the Finder Info panel to change the default application or, if you want more fine grained control use RCDefaultApp. In the default macOS config these are the same, but you can of course change the default app to your favourite text editor. (Many text editors, like BBEdit and Atom, have their own CLI tool, but if they don’t, you can use open -t instead.)

You can even pipe text into open with the -f option:

$ ls -l ~ | open -f     # TextEdit, '-e' is implied
$ ls -l ~ | open -tf    # default application assigned to txt

You can set your $EDITOR environment variable: EDITOR='open -tnW'; export EDITOR and then command lines tools that expect text from an editor, like git commit, will get the text from open and thus your default text editor instead. The -n option will actually open a new (sometimes second) instance of the application and the command line tool will resume when you quit this new instance. This a somewhat awkward workflow for Mac users. Many text editors provide a command line tool that may work better in these cases. For BBEdit the correct $EDITOR value is bbedit -w --resume.

Showing Files in Finder

If you are working on a file in Terminal and want to locate it in Finder, open can do better than just opening the enclosing folder. It can select a given file as well:

$ open -R helloworld.swift

Will open a Finder window with the enclosing folder of helloworld.swift and select the file. (You can pass multiple files into open -R but it will only select the last file in the list.)

URLs

Finally there is one more useful thing you can open:

$ open https://scriptingosx.com   # default browser
$ open vnc://TestMac.local       # Screen Sharing
$ open x-man-page://open         # show man page in Terminal

and, as always, you can use the -a option to override the default application:

$ open -a Firefox https://scriptingosx.com

Header files

For the sake of being complete: you can also open header files quickly with open. The -h option will search and open the header file for a given class. There is an additional -s option to choose an SDK:

$ open -h NSTask
$ open -h NSTask -s OSX10.12
$ open -h UIView.h -s iPhoneOS10.2
$ open -a BBEdit -h NSTask

If the search term is ambiguous open will list all the options.

Terminal–Finder Interaction

Mac Admins have to work a lot in Terminal. This seems counter-intuitive for an OS that is famed for its user interaction. I can’t talk for all admins, but for me the strength of macOS/OS X was always in the combination of ‘clicky’ UI and command line. When you know what you are doing, you can get the best of both worlds.

I remember an Apple marketing slogan: “The power of Unix, the simplicity of Mac” This is from OS X Lion, so more than five years old by now. The future will show how long Apple still values the ‘powerful’ Unix underpinnings. But for now, they are still available and I am going to use them.

All of that said, the CLI and the UI are not entirely separate areas in macOS, there is a lot of overlap and there are functions in Finder and Terminal that allow for quick interaction between the two.

Finder to Terminal

You can drag any folder from Finder to the Terminal application icon in the dock and Terminal will open a new window and change the working directory to the folder you dragged.

Movie 1: Drag Folder onto Terminal

You can drag the folder icon from the Finder window title bar, as well.

Movie 2: Drag Folder from Title Bar onto Terminal

When you drag any file into an open Terminal window, it will insert the full path to that file or folder with spaces and other special characters properly escaped.

Movie 3: Drag File onto Terminal

You can drag multiple files and Terminal will insert all of their paths, separated by spaces. For example you can type file[space] in Terminal and then drag multiple files into that window and hit return, to get information on the file type.

Movie 4: Drag Multiple Files onto Terminal

If you prefer, you can get the same effect with copy and paste. Just select the files in Finder, choose ‘Copy’ (⌘C), switch to Terminal and ‘Paste’ (⌘V).

Update: I knew I had forgotten one. Thanks to Elliot Jordan who pointed this one out on Twitter:

Dragging a folder into a Terminal window while holding the command (⌘) key will add cd before the path to a folder. When you command-drag a file it will cd to the enclosing folder of that file.

Movie 5: Command Drag a Folder to Terminal

Getting Finder path from Terminal

If you are already in Terminal and want to get the frontmost Finder window, we have to do some homework first. (I got the idea for this script from this post, though I have modified its solution somewhat.) This command

$ osascript -e 'tell app "Finder" to get posix path of ((target of window 1) as alias)'

will give us the correct path, but it has two downsides: a) it is awfully complex to type repeatedly and b) it fails with an error if no Finder window is open.

To avoid typing this long command every time, we have two options. You can either define the command as a function in your .bash_profile (or the respective profile for your preferred shell) or you can save it as a script in your $PATH.

To define it as a function, add this to the .bash_profile:

# prints the path of the front Finder window. Desktop if no window open
function pwdf () {
    osascript <<EOS
        tell application "Finder"
            if (count of Finder windows) is 0 then
                set dir to (desktop as alias)
            else
                set dir to ((target of Finder window 1) as alias)
            end if
            return POSIX path of dir
        end tell
EOS
}

# changes directory to frontmost Finder window
alias cdf='pwdf; cd "$(pwdf)"'

The pwdf function will just print the path to the frontmost Finder window to stdout.

There is also added an alias to quickly change directories to the frontmost Finder window. cdf will also print the path it is changing to, like the cd - command. (Which changes to the previous working directory.) This has to be defined as an alias, since scripts cannot change a shell’s working directory.

If you prefer to define the pwdf command from a script file use the following code:

Save this as a text file without extension in a folder in your $PATH, and set the executable bit with chmod +x /path/to/pwdf. You also need to remove (or comment) the function from your profile, since that would override the script.

Using the script form of osascript allows us to pass arguments into the AppleScript. (You can do that with function as well, but the syntax gets really messy quickly.) This script will list the paths to all open Finder windows with the -a|--all argument. Also when you provide a string as an argument it will search for a Finder window containing that string:

$ pwdf Pref
/Users/armin/Library/Preferences/

The open command

You can also go from Terminal to the Finder. This usually as simple as typing

$ open .

This will open the current working directory ‘.’ in a Finder window.

This is usually where most online ‘hints’ for the open command start and end. However, open has so much more to offer. So much more, in fact, that I will cover the open command in a separate article.

Update for ‘Packaging for Apple Administrators’

I have pushed an update to the Packaging for Apple Administrators book in the iBooks Store. Among a few typos and minor changes, I have added an Appendix section on legacy package formats.

If you already bought the book, you should be able to download the updated content for free. If you buy it now then you will get this update and any future ones!

If you have read and liked the book, please leave a review on the iBooks Store, I would be very grateful!

Get it on iBooks

Mac Manager Meeting – Packaging Presentation – Notes and Links

These are the links for my presentation at the Marriot Library of the University of Utah. You should soon be able to watch an archived version of the presentation here.

Thanks again for letting me speak and for watching and listening!

Slides for the Presentation (as PDF)

Packaging is Dead?

Packaging Tools

AutoPkg

Packaging Book

Mac Managers Meeting Presentation

I will be presenting on packaging Wednesday, Jan 18th (update, I had the wrong date here earlier) at the Mac Managers Meeting of the University of Utah. It will be at 1pm Mountain Time (21:00 Central European). Unfortunately, I will not be present but doing the presentation remotely. There will be a live stream and the talk will be archived to view later.

There will be a brief introduction to some basic pkgbuild and autopkg functions and a more detailed look at the new trust functionality in autopkg 1.0. I hope there will remain time for some Q&A.