How can I do this extremely simple operation in vim?
let g:string_from_shell = run_in_shell('awk ...')
You can use
system function to execute system/shell commands in vim. Then, you can store its output to a vim variable.
:let variable = system("shell command")
You can check its output by printing the variable like
:let list = system("ls -ltr") :echo list
To know more about it, give
:help system() in command line.