Pass character-wise visual selection to an external command

Question

I want to VISUAL select a piece of text character-wise and pass it to an external command.

For example I want to select only the URL from the the text below

abcde www.google.com abcde

and open it in the default browser.

But after I VISUAL selected it and ran the command

:call system('xdg-open', @*)

nothing happened

But the register * was filled with the selected contents. I tested it with:

:echo @*
www.google.com

What is the right command to achieve it?

Answer 1

prototype of system is:

system({cmd} [, {input}])

according to :help system()

If {input} is a string it is written to a pipe and passed as
stdin to the command.  The string is written as-is, line
separators are not changed.

so your final command becomes something like this:

echo www.google.com | xdg-open

which doesn't make sense, as xdg-open doesn't read from stdin. you can call

echo system('xdg-open', @*)

to check error message.

At last you can call system like this:

call system('xdg-open ' . @*)
                     ^ don't miss space

Answer 2

One can also do :!xdg-open <C-r><C-w> to shell out and grab the word under the cursor.

I’m not sure how this handles a WORD like www.google.com; it may be that <C-r><C-a> is necessary