tail.nvim

A minimal Neovim plugin that allows any buffer to follow appended lines—just like tail -f. It can optionally display a timestamp before each new line using virtual text, and highlight log level keywords (ERROR, WARN, INFO, DEBUG, TRACE).

Features

• Auto-scrolls to the bottom of any buffer as new lines are added (if already at bottom)
• Respects user scrolling: won't yank you back if you've moved up
• Works on any buffer type: nofile, plugin buffers, etc. Your mileage may vary for writeable or "exotic" buffers like :terminal
• Optional per-buffer timestamps: prefix newly inserted lines with the current time. The timestamp is drawn with virtual text, so it does not modify the file’s content.
• Optional log level highlighting: colorize ERROR, WARN, INFO, DEBUG, TRACE keywords using Neovim's diagnostic highlight groups.
• Does not move the cursor position on activation by default. Use neovim's move to end of buffer, default: Shift + g.

Demo

On synthetic logfile that has new line written to it every second:

Installation

Using a plugin manager

lazy.nvim

require("lazy").setup({
  { "thgrass/tail.nvim" },
})

packer.nvim

use { "thgrass/tail.nvim" }

Manual

git clone https://github.com/thgrass/tail.nvim ~/.config/nvim/pack/plugins/start/tail.nvim

Usage

Set up the plugin in your init.lua:

require("tail").setup({
  -- enable timestamps by default
  timestamps = false,
  -- customise the format (see `:help os.date`)
  timestamp_format = "%Y-%m-%d %H:%M:%S",
  -- customise the highlight group used for the timestamp
  timestamp_hl = "Comment",
  -- enable log level highlighting by default
  log_level_hl = false,
})

Then, from any buffer enable, disable or toggle tailing behaviour:

:TailEnable
:TailDisable
:TailToggle

Similarly, timestamps and log level highlighting are controlled:

:TailTimestampEnable
:TailTimestampDisable
:TailTimestampToggle

:TailLogLevelHlEnable
:TailLogLevelHlDisable
:TailLogLevelHlToggle

The actual following behavior might not directly work, as the cursor position is not changed on plugin activation by default for compatibility reasons. You can always use neovims integrated feature "move to end of buffer", default keymap is: Shift + g

When viewing file buffers specifically, you might have to tell vim it shall reload the file often:

" automatically notice external file changes
set autoread
" actually *check* for changes regularly
autocmd CursorHold,CursorHoldI,FocusGained,BufEnter * checktime

API

This plugin exposes the following Lua functions:

-- Lua API
-- (buffer 'bufnr' is optional; defaults to current)
require("tail").enable(bufnr)
require("tail").disable(bufnr)
require("tail").toggle(bufnr)

-- Timestamps
require("tail").timestamps_enable(bufnr, { backfill = true })
require("tail").timestamps_disable(bufnr)
require("tail").timestamps_toggle(bufnr, { backfill = false })

-- Log level highlighting
require("tail").log_level_hl_enable(bufnr, { backfill = true })
require("tail").log_level_hl_disable(bufnr)
require("tail").log_level_hl_toggle(bufnr, { backfill = false })

License

MIT