Execute shell command without filtering from Vim

Select your block of text, then type these keys :w !sh

The whole thing should look like:

:'<,'>w !sh

That's it. Only took me 8 years to learn that one : )

note: typing : after selecting text produces :'<,'> a range indicating selection start and end.

Update 2016: This is really just one use of the generic:

'<,'>w !cli_command

Which basically lets you "send" arbitrary parts of your file to external commands and see the results in a temporary vi window without altering your buffer. Other useful examples would be:

'<,'>w !wc
'<,'>w !to_file my_file

I honestly find it more useful to alter the current buffer. This variety is simply:

'<,'>!wc
'<,'>!to_file my_file

Update: my answer is nonsense.

@pixelearth's answer is good, but I had a little trouble understanding what he did exactly, so I wrote the following. This sequence of commands let's you execute wc -l on your visual selection. wc -l simply counts the number of lines passed to it.

1. In Vim go into Visual Mode using v
2. Select a few lines by going down: jjjj
3. Type : which Vim will translate to :'<,'>
4. Type w !wc -l, your complete commandline should now be :'<,'>w !wc -l
5. Press Enter to get the result of your command (in this example it would be 4)
6. Press Enter to continue editing

I don't understand what exactly happens at step 3 and 4 but I do know that it works.

One possibility would be to use system() in a custom command, something like this:

command! -range -nargs=1 SendToCommand <line1>,<line2>call SendToCommand(<q-args>) 

function! SendToCommand(UserCommand) range
    " Get a list of lines containing the selected range
    let SelectedLines = getline(a:firstline,a:lastline)
    " Convert to a single string suitable for passing to the command
    let ScriptInput = join(SelectedLines, "\n") . "\n"
    " Run the command
    let result = system(a:UserCommand, ScriptInput)
    " Echo the result (could just do "echo system(....)")
    echo result
endfunction

Call this with (e.g.):

:'<,'>SendToCommand wc -w

Note that if you press V%:, the :'<,'> will be entered for you.

:help command
:help command-range
:help command-nargs
:help q-args
:help function
:help system()
:help function-range