Problem when assigning a keybinding to open the output of a shell command in vim

Question

I wanted to have the output of a(any) shell command to open up in a vim split. Did a bit of research and found out that the command to do so was:

:new | 0read | ! ls                       ---  (or something of this form)

But the issue I am facing is that when I try to bind it to something like this :

nmap ,s :new | 0read | !            --- (without a specific command at the end)

Also tried with a specific command at the end and same result

it is showing up this error everytime I open up vim:

line  277:
E32: No file name
Press ENTER or type command to continue

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Edit : It was not exactly an issue with binding, the command had a small issue.

Use this command:

nmap ,s :new | 0read !

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Btw the accepted answer has a function implementation which is much better than this simple mapping

Answer 1

To open the output of a command in a new window:

:new +0r!ls

Note the syntax of new:

:[N]new [++opt] [+cmd]                                  :new

And for +cmd:

                                                        +cmd [+cmd]
The [+cmd] argument can be used to position the cursor in the newly opened
file, or execute any other command:
        +               Start at the last line.
        +{num}          Start at line {num}.
        +/{pat}         Start at first line containing {pat}.
        +{command}      Execute {command} after opening the new file.
                        {command} is any Ex command.
To include a white space in the {pat} or {command}, precede it with a
backslash.  Double the number of backslashes. 
        :edit  +/The\ book           file
        :edit  +/dir\ dirname\\      file
        :edit  +set\ dir=c:\\\\temp  file
Note that in the last example the number of backslashes is halved twice: Once
for the "+cmd" argument and once for the ":set" command.

So, to run a command in a new window, you can just + with :new, the command being 0r!ls. This can quickly become a pain with complex commands, though.

In an map, leaving the command to you to enter:

nnoremap ,s :new +0r!

You could also write a function to read in the command:

function! SplitRunCommand()
    call inputsave()
    let l:cmd = input('Command: ')
    new
    call append(0, systemlist(l:cmd))
    call inputrestore()
endfunction

nnoremap ,s :call SplitRunCommand()<cr>

Now, when you type ,s you'll be prompted:

Command:

Then, say:

Command: date '+%y%m%d'

And you will have a new window with the output of date '+%y%m%d'.