I have a complete installer of El Capitan as a pkg file and I need to install it. But first I need to make it an app.

I can't do it through the MAS because El Capitan is no longer available.

Is it possible to convert a package into an app?


5 Answers 5


Whilst norcal johnny's answer is good, it's missing some vital steps. So here goes:

What you really want to do is:

  1. Drag your .pkg file to somewhere like Desktop if it's still in a mounted drive
  2. If your right click doesn't have "Show Package Contents" - Open the terminal and run: pkgutil --expand InstallMacOSX.pkg installmacosxpkg
  3. Now you have a folder called installmacosxpkg. Inside this you should see your installESD.dmg file (if it's not there, give it a few minutes to finish extracting.
  4. Once finished, open the Distribution file in a text editor or just TextEdit.
  5. Look for the line function isSupportedPlatform(){ and add return true; so it reads: function isSupportedPlatform(){ return true;
  6. Now go and delete the original InstallMacOSX.pkg file.
  7. In terminal run pkgutil --flatten installmacosxpkg InstallMacOSX.pkg (this will take some time to complete, watch for the terminal command returning)

You should now be able to build install.app files on modern machines and then use that to create your bootable disks.

  • 1
    Worked for me, thanks! The only difference was that instead of "installESD.dmg" I had "InstallMacOSX.pkg" within "InstallMacOSX.pkg" along with Distribution and Resources. "InstallESD.dmg" was within the inner "InstallMacOSX.pkg". Tested on El Capitan.
    – Foti Dim
    Commented Aug 23, 2022 at 15:47
  • 1
    Doesn't work in macOS 13 which has a different directory tree.
    – Itachi
    Commented Oct 6, 2023 at 9:04
  • 1
    If dealing with Sierra, you won't find a isSupportPlatform() method but the principal still works. Change VolumeCheck(prefix) to return true; so it reads function VolumeCheck(prefix) { return true;}. Do the same with function InstallationCheck(prefix)- yes you'll delete quite a bit of code, that's okay. And away you go!
    – hanzworld
    Commented Apr 3 at 2:12

Theres no need to are this an app. Here’s what to do, since the .pkg file is basically a folder (if you will), it includes the “app” that the installer runs.

I think you are wanting to burn/run the installer from a disc/USB? (if not, you can run it from the .pkg file itself by double-clicking and mounting the installer.

That being said, this is how to locate and save the .dmg file locally.

What you want to do is:

  1. Right-click on the .pkg file > select "Show Package Contents"
  2. Open the Contents/SharedSupport folder and locate the file named InstallESD.dmg.

Copy InstallESD.dmg to another directory of your choosing. This InstallESD.dmg file is what you need to burn/run macOS installer from a DVD? USB.

Make the OS X El Capitan Bootable Installer Drive with a Terminal Command:

enter image description here

  1. Launch the Terminal application, found in /Applications/Utilities/ and enter the following command exactly (unless you changed the target volume name from ElCapInstaller to something else) onto a single line, the text will wrap because it is long, but it’s important to have proper syntax:

    sudo /Applications/Install\ OS\ X\ El\ Capitan.app/Contents/Resources/createinstallmedia --volume /Volumes/ElCapInstaller --applicationpath /Applications/Install\ OS\ X\ El\ Capitan.app --nointeraction
  2. Hit the Return key and enter the administrator password when requested.

    You’ll then see the following screen text in the Terminal:

    Erasing Disk: 0%… 10%… 20%… 30%…100%…

    Copying installer files to disk…

    Copy complete.

    Making disk bootable…

    Copying boot files…

    Copy complete.


    The target USB disk or flash drive will be erased first and then copy the files to it so that it will become a bootable OS X El Capitan installer. This can take a while to complete, so wait for the “Done” message before continuing.

When you see “Done”, that’s it, your OS X El Capitan installer drive has been created, it’s bootable, and you can use it to update as many Macs as you want to with OS X 10.11.

To boot from the installer drive, hold down the Option key during Mac system start, and select it from the startup volume menu.

Note: the OP is trying to create a bootable disc via MAS and Terminal method. In the instructions it tells you to download and save the installer, to avoid deletion after install completes and saving it for future use. It goes on to say load the .app to continue with creating the bootable disc/USB flash drive. This is why, I assume the user has worded his question as such.

  • 1
    Re "basically a folder (if you will) that.."; Do you mean dmg instead of pkg?
    – Pacerier
    Commented Feb 14, 2018 at 10:34
  • 1
    there is no "show package contents" on the right click menu of the El Capitan .pkg file
    – Mark Ch
    Commented Oct 29, 2018 at 13:13
  • 7
    So there's a step missing here:First you need to unpack the pkg with pkgutil --expand InstallMacOSX.pkg installmacosxpkg then go into the folder installmacosxpkg and follow the directions above Commented Jan 7, 2020 at 21:38
  • 2
    This seems to rely on having the `Install OS X El Capitan.app" already in your Applications folder. That's the very thing I think OP is missing, so this solution won't help. Commented Mar 2, 2020 at 6:34
  • 2
    There seems to be a missing step after getting the InstallESD.dmg file. The next step is to run a file within /Applications/Install OS X El Capitan.app, which doesn't exist yet. How do you go from having InstallESD.dmg to having the installer in your Applications folder?
    – callum
    Commented Oct 11, 2021 at 21:42

It no longer seems possible to “View Package Contents” using a right click in macOS (version 10.15.7 Catalina in 2020).

However you can use the pkgutil command in the Terminal to expand the .pkg file as described here:

The steps are essentially the same as the steps in Adam Collingburn‘s answer.


You'll need to re-download the OS X El Capitan Installer from the Mac App Store, under the Purchased tab.


Just run the pkg and it installs the installer

  • Welcome to Ask Different and thank you for your answer. :) Unfortunately, short answers such as this don't really provide enough detail or context to help many users. If possible, it'd be good if you could add some more info on your answer (e.g. how to run the .pkg file, what to expect, etc). Also, you may want to read How to Answer for tips on providing answers here.
    – Monomeeth
    Commented Mar 23, 2021 at 11:04

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