About the usage of core.gitproxy.

On Ubuntu 20.04, I noticed the following document for `core.gitProxy':

$ man git-config |egrep -A13 -i '^[ ]*core.gitproxy'
       core.gitProxy
           A "proxy command" to execute (as command host port) instead
of establishing direct connection to
           the remote server when using the Git protocol for fetching.
If the variable value is in the
           "COMMAND for DOMAIN" format, the command is applied only on
hostnames ending with the specified
           domain string. This variable may be set multiple times and
is matched in the given order; the
           first match wins.

           Can be overridden by the GIT_PROXY_COMMAND environment
variable (which always applies
           universally, without the special "for" handling).

           The special string none can be used as the proxy command to
specify that no proxy be used for a
           given domain pattern. This is useful for excluding servers
inside a firewall from proxy use,
           while defaulting to a common proxy for external domains.

For my case, I've a local socks5 proxy running on "127.0.0.1:18888", how should I set the above option so that the following command can pick up this proxy:

$ git clone git@github.com:torvalds/linux.git

Regards