nitrogen random configuration for two screen in nim

nitrogenrnd.nim

import os,
    re,
    strformat,
    random

var bgDir = ""
if paramCount() > 0:
    bgDir = paramStr(1)
else:
    echo "usage: nitrogenrnd [directory]"
    quit(1)

var count = 0
var i: int

if existsDir(bgDir):
    randomize()
    var bgFile0 = ""
    var bgFile1 = ""
    var rndFile0: int
    var rndFile1: int
    for file in walkDirRec bgDir:
        if file.match re".*\.(jpg|png)":
            inc(count)

    rndFile0 = rand(count)
    rndFile1 = rand(count)
    i = 0
    for file in walkDirRec bgDir:
        if file.match re".*\.(jpg|png)":
            if i == rndFile0:
                bgFile0 = file
            elif i == rndFile1:
                bgFile1 = file
            inc(i)

    echo fmt"""[xin_0]
file={bgFile0}
mode=0
bgcolor=#000000

[xin_1]
file={bgFile1}
mode=0
bgcolor=#000000
"""
else:
    quit(2)