Q:

Given the alias, get the HostName from ssh config

I have an SSH config file like:
Host myAlias
  HostName the.actual.host.name.com

Is it possible to resolve the hostname from the alias, from the shell and without connecting to the host?  I'm aiming for something like:
$ <something> myAlias
the.actual.host.name.com

A:

While it is possible to parse the ~/.ssh/config with a simple awk script, it might not work for arbitrary config file, which may have various blocks, etc.  Consider instead using the 'ssh -G', which will dump the parameters of an ssh session, then extract the hostname attribute
ssh -G myAlias | awk '$1 == "hostname" { print $2 }'

Note that this has the advantage of supporting all ssh configuration sources (local config, command line, global config, environment variables, etc). 
Just for completeness, quick and dirty awk solution
awk -v H="myAlias" '
tolower($1) == "host" { m=$2 == H }
tolower($1) == "hostname" && m{ print $2 }
' ~/.ssh/config

