Apple - How to Set a Short User Password in macOS Mojave and Later (10.14+)

You can also use the much more straightforward command:

pwpolicy -clearaccountpolicies

to remove the 4-character requirement for all users. The man page gives other useful examples if you want to change the policy on a per-user basis.

Optionally, learn a bit of the regular expression language - regex (this may take a while) and you can use the one crafted below for a 4 character length password. Here’s how to retrieve the configuration, edit that file, and then load it into the system:

1. pwpolicy getaccountpolicies | awk 'NR>1' > ~/Desktop/file.plist

2. nano ~/Desktop/file.plist

3. Change the quoted part to your Regex.

    policyAttributePassword matches '^$|.{4,}+'
   

4. pwpolicy setaccountpolicies ~/Desktop/file.plist

5. passwd

Presets:

• ^$|.{1,}+ : Any password. (Not the best Regex, but I didn't want to mess around with it too much.)

Confirmed this works with macOS Mojave (10.14).

Source: Modify pwpolicy in Sierra