String comparison not working as expected!

Question

So I want to figure out the Operating System and execute a piece of code based on the operating system in my .vimrc. However, I'm not able to understand where I'm going wrong.

let operating_system = system("awk -F= '/^NAME/{print $2}' /etc/os-release")
echon operating_system
echon operating_system > "CentOS Linux"
echon operating_system < "CentOS Linux"
echon operating_system ==? "CentOS Linux"
echon operating_system ==# "CentOS Linux"

This is the output I get when I start vim:

"CentOS Linux"
0100

Shouldn't ==? and ==# evaluate to 1? If not, why?

Answer 1

It's not working, because what you have inside operating_system variable is a bit more, than just CentOS Linux. First of all, those quotes " are part of the string. Checkout contents of that file. If you use = as a separator, second field actually contains " characters (at least that's the case on my system). Also, there probably is some invisible magic character at the end of string - carrige return or new line.

This should work if you change getting the operating_system variable to this:

let operating_system = join(split(system("sed -n 's/^NAME=\"\\([^\"]\\+\\)\".*$/\\1/p' /etc/os-release")))

sed will get everything inside " " part (I don't know awk that well to do this with it), and the join/split combo will remove those invisible characters.

Answer 2

Note that you don't need to execute external processes with system() which adds trailing newlines & all.

let os = matchstr(filter(readfile('/etc/os-release'), 'v:val =~ "^NAME"')[0], '.*"\zs.*\ze".*')

with:

• readfile() to read the system file
• filter() to keep only the line with NAME=
• matchstr() with extract the content of the name field (in the first line [0])

BTW, /etc/redhat-release also has the information you're looking for.

let is_centos = readfile('/etc/redhat-release')[0] =~ 'CentOS Linux'