:!%

“%” is a shortcut for the current filename. For this to work, the current file (%) should be in your $PATH. Or if that’s inconvenient or unwise, you can always just make the call to the file’s absolute path by substituting % with the absolute path of the file. The file should be executable, which, if it isn’t, you change by typing

:!chmod +x %

Of course, if you have just created the file, you’ll need to do a :w to actually commit the file to the filesystem, before you can make any calls to it.

Remember to use

:!!

to repeat the last command you just ran from within vi to save yourself more typing.