On Mon, 25 Nov 2019 10:47:47 -0500, Steven Schveighoffer wrote:

Though it appears that you aren't actually
exiting the program? Ctrl-Z backgrounds the program, that won't kill it.
Ctrl-D doesn't kill the application, but exits your shell.

I run dub again to create a new project.

$ dub init hello --type=vibe.d
$ cd hello
$ dub

It works fine for the first time. When I execute it for the second time using dub, I get the same error message that I mentioned above.

$ ps aux | grep hello
erdem 2688 0.0 0.2 306464 11464 pts/0 Tl 22:58 0:00 ./hello

I tried to kill application from the command line.

$ kill 2688
$ sudo kill 2688

When I check it still runs in the background.

The only change I made from normal installation was to change linker as suggested here.

vibe.d faster linking