createinstalliso

Creates a bootable ISO image from a macOS installer application. This image can then be used to install macOS on a physical or virtual machine.

Table of Contents

• Introduction
• Requirements
• Compatibility
• Installation
• Usage
  • Command line arguments
  • Example
• Troubleshooting
  • Alert during macOS installation
• References
  • Installer application types -Required external commands
  • Exit status and messages
• License

Introduction

If you have ever needed to install macOS on a new computer, you have probably discovered the ability to create a bootable USB flash drive or other volume by using the createinstallmedia command included in the downloaded macOS installer: Create a bootable installer.

In case you need a bootable ISO image instead, you can find a lot of shell scripts in forums that create such an ISO image for certain macOS versions. However, they are often only written for a single macOS version and cannot adapt to the specific macOS version contained in the installer.

The purpose of this program createinstalliso is to create a bootable ISO image from a downloaded full macOS installer. In addition, the program should:

• Automatically adapt the strategy used to create the ISO image to the installer application type, thereby supporting a wide range of macOS versions (see: Compatibility).
• Look and feel like Apple's createinstallmedia command (e.g. handling of command line arguments, wording for error and progress messages, status codes used when exiting).
• Behaving like a standard command line program (e.g. Ctrl-C interruptibility, proper cleanup of resources before exiting), even though it is a Bash script.

Requirements

To run createinstalliso you need:

• A machine running Mac OS X Snow Leopard 10.6 or later.
• An administrator user and password required for the use of the sudo command.
• A downloaded full macOS installer for Mac OS X Lion 10.7 or later.

Note: Make sure that you have downloaded a full macOS installer which should have a size of at least 5 GB.

Compatibility

macOS version

The table below shows:

• Whether a macOS version can run createinstalliso.
• Which macOS installers can be used to create an ISO image with this particular macOS version.

macOS	Version	Can run createinstalliso	Can use installer for
Mac OS X Cheetah	10.0	No	N/A
Mac OS X Puma	10.1	No	N/A
Mac OS X Jaguar	10.2	No	N/A
Mac OS X Panther	10.3	No	N/A
Mac OS X Tiger	10.4	No	N/A
Mac OS X Leopard	10.5	No	N/A
Mac OS X Snow Leopard	10.6	Yes	10.7 - 10.11
Mac OS X Lion	10.7	Yes	10.7 - 10.11
OS X Mountain Lion	10.8	Yes	10.7 - 10.15
OS X Mavericks	10.9	Yes	10.7 - 12
OS X Yosemite	10.10	Yes	10.7 - 12
OS X El Capitan	10.11	Yes	10.7 - 13
macOS Sierra	10.12	Yes	10.7 - 13
macOS High Sierra	10.13	Yes	10.7 - 15
macOS Mojave	10.14	Yes	10.7 - 15
macOS Catalina	10.15	Yes	10.7 - 15
macOS Big Sur	11	Yes	10.7 - 15
macOS Monterey	12	Yes	10.7 - 15
macOS Ventura	13	Yes	10.7 - 15
macOS Sonoma	14	Yes	10.7 - 15
macOS Sequoia	15	Yes	10.7 - 15

Installer version

The table below shows:

• Which macOS version is required to use createinstalliso with a particular macOS installer.

Installer for	Version	Required macOS version
Mac OS X Cheetah	10.0	N/A
Mac OS X Puma	10.1	N/A
Mac OS X Jaguar	10.2	N/A
Mac OS X Panther	10.3	N/A
Mac OS X Tiger	10.4	N/A
Mac OS X Leopard	10.5	N/A
Mac OS X Snow Leopard	10.6	N/A
Mac OS X Lion	10.7	10.6 or later
OS X Mountain Lion	10.8	10.6 or later
OS X Mavericks	10.9	10.6 or later
OS X Yosemite	10.10	10.6 or later
OS X El Capitan	10.11	10.6 or later
macOS Sierra	10.12	10.8 or later
macOS High Sierra	10.13	10.8 or later
macOS Mojave	10.14	10.8 or later
macOS Catalina	10.15	10.8 or later
macOS Big Sur	11	10.9 or later
macOS Monterey	12	10.9 or later
macOS Ventura	13	10.11 or later
macOS Sonoma	14	10.13 or later
macOS Sequoia	15	10.13 or later

Installation

Open Terminal, which is in the Utilities folder of your Applications folder, and type or paste the following commands into Terminal:

• Download the createinstalliso file.

  curl -fOSs https://raw.githubusercontent.com/BITespresso/createinstalliso/master/createinstalliso
  

• Make the downloaded script executable.

  chmod +x createinstalliso
  

• A good practice is to keep your shell scripts in the bin folder in your home directory. If it does not already exist, create it and move the script to this folder.

  mkdir -p ~/bin
  mv createinstalliso ~/bin/
  

• You might also want to hide the bin folder from the Finder.

  chflags hidden ~/bin
  

Note: Of course you can also choose a different folder such as /usr/local/bin to save the script.

Usage

Just like Apple's createinstallmedia command createinstalliso must be run as root user. Depending on where you saved the script, the command will look like:

sudo ~/bin/createinstalliso --isodirectory <path to ISO directory> --applicationpath <path to OS installer application> [--nointeraction]

Command line arguments

The command createinstalliso requires the following two command line arguments:

• --isodirectory (or -i) must be followed by a path to a directory where the installer ISO image file will be created.
• --applicationpath (or -a) must be followed by a path to a copy of the OS installer application to create the bootable ISO image from.

The name of the ISO image to be created is made up of the name of the installer and has the extension iso (e.g. Install macOS Catalina.iso). If such a file already exists in the specified destination directory, you will be prompted for confirmation before this file is overwritten. If you do not care about overwriting an existing file and do not want to be prompted, you can add the command line option --nointeraction.

If you want to suppress user interactions when running the command and always allow the required actions, you can add the option:

• --nointeraction (or -n) causes an existing ISO image file to always be overwritten.

Example

The following example show the steps required to create an ISO image from a macOS Catalina installer:

• Open Terminal, which is in the Utilities folder of your Applications folder.

• Type or paste the following command into Terminal, then press Return to enter the command. This assumes that the installer is still in your Applications folder, and you have moved createinstalliso to the ~/bin folder.

  sudo ~/bin/createinstalliso --isodirectory ~/Desktop/ --applicationpath /Applications/Install\ macOS\ Catalina.app/
  

• When prompted, type your administrator password. Terminal doesn't show any characters as you type. Then press Return.

• Terminal shows the progress as the bootable ISO image is created.

• When Terminal says that it's done, you will find the bootable ISO image Install macOS Catalina.iso in the folder you specified (here: ~/Desktop).

• You can now quit Terminal.

Troubleshooting

Alert during macOS installation

If you try to install macOS using the ISO image you created, you may see an alert that says the application can't be verified and may have been corrupted or tampered with during downloading. Or it says that the package was signed with a certificate that has expired and may not be authentic (see: If an installer says it can't be verified or was signed with a certificate that has expired).

The most likely reason for this message is that the installer was signed with a certificate that expired on October 24, 2019. You must therefore either get a new installer signed with a currently valid certificate or temporarily set the system date to a date in the past when the certificate was still valid.

To manually set the system date to a value in the past, perform the following steps after the above warning is displayed during the macOS installation:

• Close the alert.
• Open Terminal from the Utilities menu.
• Type date 100800002019 into Terminal, then press Return. This sets the system date to October 8, 2019, 0:00 am.
• Quit Terminal and resume the macOS installation.

References

Installer application types

Apple has used different internal structures for its macOS installers over time. Therefore, createinstalliso examines the internal structure of the installer and determines which 'type' it is. Based on this 'type', the necessary steps to create a bootable ISO image are performed.

The installer application types are:

Name	Version	Type
Mac OS X Lion	10.7	1
OS X Mountain Lion	10.8	1
OS X Mavericks	10.9	2
OS X Yosemite	10.10	2
OS X El Capitan	10.11	2
macOS Sierra	10.12	3
macOS High Sierra	10.13	3
macOS Mojave	10.14	3
macOS Catalina	10.15	3
macOS Big Sur	11	4
macOS Monterey	12	4
macOS Ventura	13	4
macOS Sonoma	14	4
macOS Sequoia	15	4

Required external commands

createinstalliso uses a number of external commands, which must be available on your system:

• awk
• bless
• codesign
• cp
• cut
• df
• ditto
• du
• file
• grep
• hdiutil
• mktemp
• ps
• pwd
• rm
• rsync
• script
• seq
• stat
• sw_vers
• sysctl
• tput
• uname
• xattr
• /usr/libexec/PlistBuddy.

Unless you have deliberately modified your system, all of the above commands are available on the macOS versions listed in the section "Compatibility".

Exit status and messages

A failure of createinstalliso is indicated by a non-zero exit status. Wherever possible, createinstalliso uses an exit status and and exit message identical to createinstallmedia.

The table below lists all possible exit status and corresponding messages:

Status	Message
255	You must specify both the ISO directory and install application path.
255	createinstalliso: unrecognized option `[OPTION]'
255	createinstalliso: invalid option -- [OPTION]
255	createinstalliso: option `[OPTION]' requires an argument
255	createinstalliso: option requires an argument -- [OPTION]
255	createinstalliso: option `[OPTION]' doesn't allow an argument
255	createinstalliso: option `[OPTION]' is ambiguous
254	[DIRECTORY] is not a valid ISO directory.
253	[FILE] does not appear to be a valid OS installer application.
252	This tool must be run in Bash shell.
251	Couldn't get operating system name.
250	This tool must be run on macOS.
249	This tool must be run as root.
248	Couldn't get macOS version.
247	Invalid macOS version.
246	[VOLUME] is not large enough for [FILE(S)]. An additional [SIZE] is needed.
245	This tool requires [VERSION] or later.
244	Couldn't get absolute path for [FILE].
243	Couldn't get absolute path for [DIRECTORY].
242	Couldn't get installer application display name.
241	Couldn't get installer application type.
240	Failed to create temporary directory.
239	Couldn't get device ID.
238	You need [VERSION] or later to create an ISO image from this installer application.
237	Failed to delete the [FILETYPE] [FILE].
236	Mount of outer dmg failed.
235	BaseSystem missing from the outer dmg, damaged installer image?
234	Failed to convert BaseSystem.dmg.
233	Failed to resize disk image.
232	The disk image did not mount.
231	Failed to delete Packages symlink.
230	Failed to copy Packages directory.
229	The bless of the installer disk image failed.
228	Failed to copy BaseSystem.dmg.
227	Failed to copy BaseSystem.chunklist.
226	Couldn't unmount disk image.
225	Failed to create disk image.
224	Failed to convert disk image into bootable install media.
223	Failed to create ISO image.
222	[NOT USED SINCE 1.1]
221	Couldn't get installer application minimum macOS version.
220	Failed to copy installer application.
219	Failed to remove extended attribute com.apple.quarantine.
218	Failed to patch macOS Sierra installer application.
217	Failed to replace code signatures.
216	Failed to replace modified files with original ones.

License

Copyright (C) 2021-2024 Michael Berger (BITespresso)

createinstalliso is licensed under the GNU General Public License v3 (GPL-3) (http://www.gnu.org/copyleft/gpl.html).