A Lua script that removes lines from a file.

rmlines.lua

#!/usr/bin/lua

--[[
    Removes lines from a file

    @param  string  filepath
    @param  num     startline (line number where deletion starts)
    @param  num     numlines  (number of lines to delete)

    ex: $ rmlines ~/myfile 45 7
--]]

local params    = {...}
local filename  = params[1]
local startline = tonumber(params[2])
local numlines  = tonumber(params[3])

local fp = io.open(filename, "r")
if fp == nil then return nil end

local content = {}
local i = 1;

for line in fp:lines() do
    if i < startline or i >= startline + numlines then
        content[#content+1] = line
    end
    i = i + 1
end

fp:close()
fp = io.open(filename, "w+")

for i = 1, #content do
    fp:write(string.format("%s\n", content[i]))
end

fp:close()