---
title: Vim Send To Terminal
date: 2023-07-15T20:18:03-04:00
asciinema: true
tags:
    - vim
categories:
    - development
---

### Semi automatic scripts with vim `:terminal`

<!--more-->

Sometimes, fully automating a task is not worth the effort. So I end up running
a set of commands usually from a cheat sheet text file slightly modifying the
arguments each time. I used the below in vim to send line under cursor to vim's
`:terminal` open in a split 
```vim
:call term_list()[0]->term_sendkeys(getline('.') .. "\<CR>")
```
To send another line `@:` and then for every other line `@@`.  This works because, last
command run is stored in `register :` and the last macro executed using `@` is
stored in `register @`.

To do the same another day, `:call te<UP arrow>` to recall from vim's command
history. Or better, add a function and mapping.

```vim
def SendToTerminal()
    if term_list()->empty()
        echomsg "No Terminal windows found"
        return
    endif
    terms[0]->term_sendkeys(getline(.) .. "\<CR>")
enddef

nnoremap <silent><leader>s call SendToTerminal()<CR>
```

### More cool features

For most use-cases that was enough. However added a few more nice features
which is very helpful when you need it

1. Support sending a range of lines (visual selection) at a time. E.g. Send a
   function block to a python shell
2. Add a delay between lines in milliseconds. This is useful when the previous
   command reads from standard input and takes some time to complete
3. Support sending `ctrl` characters like `ctrl d`, `ctrl c` etc,

```vim
vim9script
def SendRangeToTerminal(start_line: number, end_line: number, _ = 0)
    const terms = term_list()
    if terms->empty()
        echomsg "No Terminal windows found"
        return
    endif
    var line_num = start_line
    for line in getline(start_line, end_line)
        line_num += 1
        const spl_cmd = line->matchlist('\vVIMST (sleep|ctrl) ([0-9]+|[a-z])?')
        if !spl_cmd->empty()
            const [_, cmd, arg1; _] = spl_cmd
            if cmd == "sleep"
                timer_start(arg1->str2nr(), funcref('SendRangeToTerminal', [line_num, end_line]))
                return
            elseif cmd == "ctrl"
                terms[0]->term_sendkeys(nr2char(arg1->char2nr() - 96))
                continue
            endif
        endif
        terms[0]->term_sendkeys(line .. "\<CR>")
    endfor
enddef

command -range -bar SendToTerm :call <SID>SendRangeToTerminal(<line1>, <line2>)
vnoremap <silent><leader>s :SendToTerm<CR>
nnoremap <silent><leader>s :SendToTerm<CR>
```

### More cool mapping

Wouldn't it be nice to just double-click commands with mouse? Like a simple GUI! ;)

```vim
nnoremap <silent><2-LeftMouse> :SendToTerm<CR>
```

Or just `Enter`?

```vim
nnoremap <buffer> <CR> :SendToTerm \| norm j<CR>
```

Of course, mapping `Enter` for any file is a bad idea. So lets just map in our cheat file

```vim
autocmd BufNewFile,BufRead cheat.sh {
    nnoremap <buffer> <silent><2-LeftMouse> :SendToTerm<CR>
    nnoremap <buffer> <CR> :SendToTerm \| norm j<CR>
}
```

### Demo

{{< asciinema key="vimstt" >}}

### Getting the scripts

### What about neovim/tmux/screen?

I am not the only one who thought about this. See
[vim-slime](https://github.com/jpalardy/vim-slime) since 2007. However it does
not support adding a sleep or sending arbitrary `ctrl` characters without
additional mappings