shared vimrc on two machines; only run command for one of them

Question

I use git to share my vimrc across multiple machines. But now I have some commands which I only want on one machine. Namely, this line: au! redhat BufReadPost (derived from this very helpful answer! https://unix.stackexchange.com/questions/59486/disable-vi-from-going-to-the-last-visited-line-upon-file-opening)

Is there a way to load this line only for my linux machine? Or maybe put into a second vimrc file which only exists/loads on linux? Or maybe another solution, so that I can keep using version control for the rest of my files but let this one command apply just for this one machine?

Answer 1

You can surround the config/code in question with a conditional based on an environment variable.

If you're using Bash environments a good candidate is envvar HOSTNAME which will probably be unique (in a personal context, at least). In other environments there is usually a way to get this same information (e.g. output of the *nix command hostname or envvar COMPUTERNAME on Windows). If you have a heterogeneous mix of machines then the best approach is probably to use the Vim function hostname() which provides a platform agnostic means of getting the information.¹

For simplicity, we'll pretend we're all in on Bash. :) For the example you mentioned we'd just need to add something like...

 if $HOSTNAME == "foo"
     au! redhat BufReadPost ...
 endif

Of course, we can also extend this to multiple hosts and/or have default settings...

 if $HOSTNAME == "foo"
     " this config
 elseif $HOSTNAME == "bar"
     " that config
 else
     " default config
 endif

Before you set it up check availability with :echo $HOSTNAME.

If you want to look for alternatives you could run :!printenv or :!env or whatever your system's equivalent command is. In the unlikely event that you can't find an existing envvar that will work then make something up! Choose a variable name not currently in use and on the machine(s) you want to isolate put (assuming Bash, again) export MYSPECIALVAR=uniquevalue in your .profile, .bash_profile, .bashrc or whatever makes the most sense for your environment.

¹_{Thanks to @Achilleas for spurring me to expand/improve this section.}