Vim expands percent sign '%' in URL

Question

In my script, I am trying to open an URL in my default browser using

silent exec '!rundll32 url.dll,FileProtocolHandler '.a:url

where a:url is an URL-encoded string containing percent % signs. Vim obviously expands the percent sign with the current file name, resulting in an URL like

https://slovnik.seznam.cz/preklad/cesky_nemecky/bohatmyFile.txtc3myFile.txtbd

instead of

https://slovnik.seznam.cz/preklad/cesky_nemecky/bohat%c3%bd

(Remark: The encoded string stands for "bohatý" - "rich" in Czech)

How can I prevent VIM from expanding the percent sign?

Answer 1

You can use the escape() function to escape characters that are interpreted as meta-characters, such as % (also # and ! in the case of running an external command with :!.)

In your case:

silent exec '!rundll32 url.dll,FileProtocolHandler '.escape(a:url, '%#!')

One alternative, particularly as you're using silent, so not interested in the command's output, is to use the system() function call directly, which doesn't do as much command-line mangling as :! does.

call system('rundll32 url.dll,FileProtocolHandler '.a:url)

One advantage of system() (or systemlist()) is that you can get the output of the commands as a Vimscript string (or list of lines), if you wish to inspect or manipulate them after the command has finished running.