How can I determine the Linux distro in vimscript?

Question

In shell I do conditional stuff depending on distro like this:

eval "$(source /etc/os-release && typeset -p ID)"
if [[ $ID =~ ^(rhel|fedora.*|amzn|ol|rocky|almalinux)$ ]]; then
  ...
fi

How could I do that in vimscript?

Answer 1

As I pointed out in my comment, I suspect it's an XY problem. I wouldn't read any files in /etc in Vim at all. Although I have to say I'm delighted to have read some great answers.

A comment on the question says the same dotfiles are used on all machines and I think that's where things start to go wrong. Those are configuration files, they are meant to be configured. So allow for some system-specific tweaking.

I would propose a distro-agnostic approach of reading from an optional, machine-specific configuration file like this:

" set defaults that make sense
" ...
if filereadable(expand('~/.vim/overrides/distro.vim'))
    source ~/.vim/overrides/distro.vim
endif

You can put the config file next to your Vim configuration like in my example or specify another path. See :help filereadable() and :help expand() for usage information.

There are two more points to consider which largely depend on how the machines are set up and dotfiles are deployed. There's nothing about it in the question so I'll have to guess a little.

You can write distro.vim e.g. from a shell script much like that in the question or a makefile when you set up a new machine and install your dotfiles. A less favorable option would be to write it from a shell profile whenever you log in.

Also, the configuration should be ignored in whatever tool is used to setup the dotfiles, e.g. add it to .gitignore if Git is what you use.

Main advantages of this approach:

• easy to adapt to allow for other distinguishing features other than Linux distro.
• equally easy to expand or make exceptions. You can script something or just edit that file.
• uses both shell script and Vim for what they're good at.
• comes with the minimal performance penalty of sourceing another file and re-setting some options. You should not be able to notice.

Answer 2

Here's my version:

:echo readfile('/etc/os-release')->filter({k,v -> v =~# '^ID='})[0]->slice(3)

This errors if !filereadable('/etc/os-release') and assumes the line of interest is exactly ID=<value>. If the file must be interpreted by a shell to be correct, something like Vivian's answer using source in systemlist() is probably more appropriate.

Answer 3

I would do:

let distrib = system('source /etc/os-release && typeset -p ID')
if distrib =~ '(rhel|fedora.*|amzn|ol|rocky|almalinux)'
  " ...
endif

Answer 4

Will this work ?

function! GetLinuxDistro()
    let os_release_path = '/etc/os-release'
    
    if filereadable(os_release_path)
        let os_info = readfile(os_release_path)
        for line in os_info
            if line =~ 'PRETTY_NAME'
                return substitute(line, 'PRETTY_NAME="\(.*\)"', '\1', '')
            endif
        endfor
    endif
    
    return 'Unknown Linux Distribution'
endfunction

echo GetLinuxDistro()

Answer 5

I've started using different terminal colours on different machines/servers to help me know where I am and wanted to change the vim colourschemes to match. I can't think of a better way to differentiate as they all use the same dotfiles. I could use hostnames, but this would not need updating.

Or you could:

• make sure all your shells expose an appropriate $TERM, like xterm-16color,
• and use a 16color-ready colorscheme in Vim, like default and any of the other built-in ones or this one or that one.

That way, Vim doesn't need to be aware of where it is running; it always shows the expected colors.