I have created a package installer for MacOS with "productbuild" command line and adding the postinstall script in the package through command. And even I have changed the file mode to executable "chmod a+x" before using it in "productbuild" command. Here is what I am using for command line and in postinstall script and I have name the file to "postinstall.sh". command line:- productbuild --component "$appDir" "/Applications" --scripts "../Scripts" --sign "Developer ID Installer: $DEVNAME" "$appName.pkg" postinstall.sh:- #!/usr/bin/env bash open -n -a /Applications/appname.app exit 0 when package is created and I try to install the application on my mac, Installation runs smooth and app is install under application folder but postinstall script does not for some reason. please advise if I have missed out something or anything on running the postinstall script would be appreciated. Thanks in advance Note : This app is generated by Unity engine.