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Monitoring files with vim

It turns out that monitoring a file with vim is harder than it should be. Scripts such as Tail-Bundle and WatchForChanges rely on vim’s CursorHold events which only trigger once. Unlike tail -f, they only work if you’re active in that vim session and pressing keys to cause CursorHold to re-arm.

tail -f works well, but lacks the syntax highlighting and other features from vim.

Some other options require 2 terminals, or 2 separate scripts.

The solution below is very similar to tail -f. The primary difference is that it only monitors a single file at a time.

Get the latest version from: https://gist.github.com/4a334b61e1c34b438ccd.git

#!/bin/bash

# Usage: vim-tail.sh <filename>
#
# This script turns vim into a `tail -f` equivalent, but with syntax
# highlighting and all the other goodies.
#
# A version of vim compiled with +clientserver is required.
# On Ubuntu 14.04, vim.tiny, vim.basic and vim.nox won't work.
# vim.gtk is compiled with +clientserver, so `apt-get install vim-gtk`
#
# Author: Gabriel Burca <gburca dash github at ebixio dot com>

# Pick one of: vim|view|gvim|gview, etc...
VI=vim.gtk

# A unique name for the server, in case we monitor multiple files.
NAME="TAIL$$"

doForever() {
    # Give the vim server a chance to start
    sleep 2

    # Move to the end of the file
    $VI --servername $NAME --remote-send '<C-\><C-N>:edit!<CR>G' > /dev/null 2>&1 || exit

    while true; do
        # This blocks until the file changes, or the timeout expires
        inotifywait --quiet --quiet --timeout 10 --event modify "$1"
        # 0 = the file was modified
        # 2 = the timeout expired
        if (( $? == 0 || $? == 2 )); then
            $VI --servername $NAME --remote-send '<C-\><C-N>:edit!<CR>G' > /dev/null 2>&1 || exit
        else
            exit 1
        fi

        # It's possible for the file to be modified before we loop back to
        # `inotifywait`, but we'll pick it up on the next round.
    done
}

# Kick off the vim client script in the background
coproc doForever "$1"

# Now start the server
$VI --servername $NAME --remote-silent "$1"
# Nothing below here executes until the `tail` server exits.
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