How to pass generic shebang line to shell

Question

As far as I know, all "good" scripts/programs start off with a shebang line as the first line:

#!/bin/bash
#!/usr/bin/env python
#!/usr/bin/perl

etc. Is it possible to pass that line to Vim in command-mode to generically determine the program to use when executing the current file.

For example, perl file needs

:! perl%

Python,

:! python%

If the shebang is already there in the file, is it possible to replace the specific program before the % character (current file) with the shebang line/argument?

Of course, if the file is executable already :! ./% works

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The idea is to map a key so that, as you write code, simply hitting a shortcut key the file is executed; mimicking an IDE.

Once again, assuming the file is not (yet) executable, since you just started writing it in Vim.

Answer 1

I'm not sure this is what you want but you could try this mapping using the <F7> key:

nnoremap <F7> :<C-U>sil! exe '!' . matchstr(getline(1), '#!\zs.*') . ' ' . shellescape(expand('%:p'), 1) <Bar> redraw!<CR>

• matchstr(getline(1), '#!\zs.*') extract the text after the shebang
• shellescape(expand('%:p'), 1) expand the full path to the current file and protect characters that may have a special meaning for the shell; the second non-nul argument is useful to escape special items such as !, %, # which could be expanded by Vim on the command-line

If you want to see the output in the shell, you could remove :sil! and :redraw!:

nnoremap <F7> :<C-U>exe '!' matchstr(getline(1), '^#!\zs.*') shellescape(expand('%:p'), 1)<CR>

Answer 2

You could use the fact that your shell understands the Shebang:

:!./%

Please be sure to make your file executable (chmod +x filename). You can easily create a mapping for this, so that you can execute your current file with one keypress.

Answer 3

If for some reason @cbaumhardt's answer doesn't work for you, you can actually just use perl. As a handy helper for systems that don't handle shebang lines correctly, perl will actually honor the shebang line itself. See this question on SO for more info about that.