Example output from running ./createOSXinstallPkg --source "/Applications/Install macOS Sierra.app" --pkg "/Users/username/createOSXinstallPkg/first_boot/Sierra First Boot Package Install.pkg" --output "Sierra 10.12.1 Installer.pkg"

gistfile1.txt

computername:createOSXinstallPkg username$ sudo ./createOSXinstallPkg --source "/Applications/Install macOS Sierra.app" --pkg "/Users/username/createOSXinstallPkg/first_boot/Sierra First Boot Package Install.pkg" --output "Sierra 10.12.1 Installer.pkg"
Password:
Examining and verifying source...
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InstallESD.dmg: /Applications/Install macOS Sierra.app/Contents/SharedSupport/InstallESD.dmg
OS Version: 10.12.1
OS Build: 16B2659
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Output path: /Users/username/createOSXinstallPkg/Sierra 10.12.1 Installer.pkg
Additional packages:
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Sierra Upgrade First Boot Package Install.pkg
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Total additional package size: 13700 Kbytes
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Checking available space on /Applications/Install macOS Sierra.app/Contents/SharedSupport/InstallESD.dmg...
Creating package wrapper...
Copying brtool into package resources...
Creating MacOSXInstaller.choiceChanges...
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Downloading and adding IncompatibleAppList pkg...
Downloading http://swcdn.apple.com/content/downloads/17/04/031-83163/n8thccuwnoqetn1kyn53bheb4nb7pw3wbv/OSX_10_12_IncompatibleAppList.pkg to /Users/username/createOSXinstallPkg/Sierra 10.12.1 Installer.pkg/Contents/Resources/OS X Install Data/OSX_10_12_IncompatibleAppList.pkg...
Writing index.sproduct to /Users/username/createOSXinstallPkg/Sierra 10.12.1 Installer.pkg/Contents/Resources/OS X Install Data/index.sproduct...
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Copying InstallESD into package...
Mounting /Applications/Install macOS Sierra.app/Contents/SharedSupport/InstallESD.dmg...
Copying additional packages to InstallESD/Packages/:
    Copying flat package /Users/username/createOSXinstallPkg/first_boot/Sierra Upgrade First Boot Package Install.pkg
Creating /private/tmp/tmpAFfTca/dmg.4raGx3/Packages/OSInstall.collection
Unmounting /Applications/Install macOS Sierra.app/Contents/SharedSupport/InstallESD.dmg...
Creating disk image at /Users/username/createOSXinstallPkg/Sierra 10.12.1 Installer.pkg/Contents/Resources/InstallESD.dmg...
Preparing imaging engine…
Reading Protective Master Boot Record (MBR : 0)…
   (CRC32 $3A2C1859: Protective Master Boot Record (MBR : 0))
Reading GPT Header (Primary GPT Header : 1)…
   (CRC32 $6387BDC5: GPT Header (Primary GPT Header : 1))
Reading GPT Partition Data (Primary GPT Table : 2)…
   (CRC32 $9034B71B: GPT Partition Data (Primary GPT Table : 2))
Reading  (Apple_Free : 3)…
   (CRC32 $00000000:  (Apple_Free : 3))
Reading EFI System Partition (C12A7328-F81F-11D2-BA4B-00A0C93EC93B : 4)…
....
   (CRC32 $B54B659C: EFI System Partition (C12A7328-F81F-11D2-BA4B-00A0C93EC93B : 4))
Reading disk image (Apple_HFS : 5)…
........................................................................................................
   (CRC32 $6F849562: disk image (Apple_HFS : 5))
Reading  (Apple_Free : 6)…
..........................................................................................................
   (CRC32 $00000000:  (Apple_Free : 6))
Reading GPT Partition Data (Backup GPT Table : 7)…
..........................................................................................................
   (CRC32 $9034B71B: GPT Partition Data (Backup GPT Table : 7))
Reading GPT Header (Backup GPT Header : 8)…
...........................................................................................................
   (CRC32 $FC9D3E61: GPT Header (Backup GPT Header : 8))
Adding resources…
...........................................................................................................
Elapsed Time:  9m  5.775s
File size: 4887626747 bytes, Checksum: CRC32 $9B8D9D5F
Sectors processed: 10741912, 10281876 compressed
Speed: 9.2Mbytes/sec
Savings: 11.1%
created: /Users/username/createOSXinstallPkg/Sierra 10.12.1 Installer.pkg/Contents/Resources/InstallESD.dmg
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Done! Completed package at: /Users/username/createOSXinstallPkg/Sierra 10.12.1 Installer.pkg
computername:createOSXinstallPkg username$