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Basically, a Mac application has a .app./file extension, but it's not really a file - it's a package. We can view the contents of an application by navigating to it in the Finder, right-clicking it, and then selecting " Show Package Contents ".

The internal folder structure may vary from application to application, but we can be sure that every Mac application will have a Directory folder that contains a MacOS subfolder. Within the MacOS directory, there is an extensionless file with the exact same name as the application itself. This file can really be anything, but in its simplest form is a shell script. It turns out that this folder/file structure is all you need to create a functional application!

Enter appify

Following this discovery, Thomas Aylott came up with a clever "appify" script that allows us to easily create Mac applications from shell scripts. The code is as follows:

#!/usr/bin/env bash

APPNAME=${2:-$(basename "${1}" '.sh')};
DIR="${APPNAME}.app/Contents/MacOS";

if [ -a "${APPNAME}.app" ]; then
    echo "${PWD}/${APPNAME}.app already exists :(";
    exit 1;
fi;

mkdir -p "${DIR}";
cp "${1}" "${DIR}/${APPNAME}";
chmod +x "${DIR}/${APPNAME}";

echo "${PWD}/$APPNAME.app";

If you're used to UNIX, it's appifypretty simple to install and use. (I'm not, so I had to figure this out.) Here's how to install it:

1. Save the script to a directory in your PATH and name it appify (no extension). I chose to put it in /usr/local/bin. You will need root privileges.
2. Launch Terminal.app and type sudo chmod +x /usr/local/bin/appifyMake appify executable without root permissions.

After that, we can create an application based on any shell script by simply launching Terminal.app and typing:

$ appify your-shell-script.sh "Your App Name"

Obviously, this will create a standalone application called Your App Name.appyour-shell-script.sh which will execute the script.

After that we can add a custom icon to the application very easily if needed.

Add a custom application icon

1. .icnsCreate a .txt file or 512x512 PNG image with the icon we want and copy it to the clipboard ⌘ + C. (Alternatively, copy it from an existing application as described in steps 2 and 3.)
2. Right-click the file whose icon you want to change .appand choose Get Info (or select the file and press ⌘ + I).
3. Select the app icon in the top left corner by clicking it once. If you did it right, it will get a subtle blue outline.
4. Now click ⌘ + V(Paste) to overwrite the default icon with the new one.

请注意, this works for any file or folder, not just .app files.

Example

Chrome/Chromium Bootloader

I like to run with some command line switches or flags enabled Chrome/Chromium. On Windows, we can create a shortcut and set the parameters we want in its properties; on Mac, we need to launch it from the command line every time. Well, not anymore :)

#!/usr/bin/env bash
/Applications/Chromium.app/Contents/MacOS/Chromium --enable-benchmarking --enable-extension-timeline-api&

The final &is not a typo; it is used to ensure that Chromium is launched in a separate thread. If not &, Chromium will exit immediately when we exit Terminal.app.

Start a local web server from a directory

Let's say we are working on a project and want to debug it from a web server. The following shell script will use Python to start a local web server from a specific directory and open the index page in the default browser of our choice. Once applied, you don't even need to open the terminal anymore.

#!/usr/bin/env bash
cd ~/Projects/Foo/
python -m SimpleHTTPServer 8080 &> /dev/null &
open http://localhost:8080/

Needless to say, the possibilities are endless. As another example, you could easily create an application that minifies all JavaScript and CSS files in a specific folder. Got any great ideas? Let us know by leaving a comment!