The results from running a shell command can be inserted into the current buffer with the :read command, or lines can be replaced in a buffer with a filter command, or Vim's system() function can be used like the backquote syntax (aka backtick) that many Unix shells provide to capture command output, which you can then use in a script or expression-register ([help quote=]) to insert in the buffer or parse in some way. The following examples capture the output of the shell's date command. This is just an example: it is better to use Vim's strftime() function to get the date or time.