How to create an installable cert file on macos ?

[ladyrick]

Failed case

I run this command to generate cert file and key file:

./mkcert -cert-file http.crt -key-file http.key mydomain.xxx

After that I double click the http.crt file to install it on system.
Then I trust the cert on macos keychain app.

Now, safari works fine but chrome still report a NET::ERR_CERT_AUTHORITY_INVALID

Success case

I run this command to generate files and automatically install:

./mkcert -install -cert-file http.crt -key-file http.key mydomain.xxx

Now both safari and chrome work fine.

I (using macos keychain app) export a cer file and rename it to exported.cer.
With this exported.cer file, I can manually install it without mkcert installed.
This is convenient for distributing my cert to others.

This exported.cer file is what I want.

My question

How to generate the exported.cer file directly by mkcert?
Or further, how to generate an exported.cer file for macos on linux system?