ComputerCraft: Tree Command (not final) by Espen

-- Context: http://www.computercraft.info/forums2/index.php?/topic/44-request-windows-tree-command/

local tArgs = { ... }
local currentPath = shell.resolve(".")
local lineCounter = 0
local pageFlip = false
local askingForHelp = false

--[[ Process command line arguments ]]
if #tArgs > 1 then  -- More than one argument.
    if ( tArgs[1] == string.lower( "-m" ) ) or ( tArgs[1] == string.lower( "-more" ) ) then
        pageFlip = true
        currentPath = shell.resolve( tArgs[2] )
    elseif ( tArgs[2] == string.lower( "-m" ) ) or ( tArgs[2] == string.lower( "-more" ) ) then
        pageFlip = true
        currentPath = shell.resolve( tArgs[1] )
    else
        currentPath = shell.resolve( tArgs[1] )
    end
else    -- Only one argument.
    if ( tArgs[1] == string.lower( "-h" ) ) or ( tArgs[1] == string.lower( "-help" ) ) then
        askingForHelp = true
    elseif tArgs[1] ~= nil then
        currentPath = shell.resolve( tArgs[1] )
    end
end

function printUsage()
    print( "Usage: tree [-more] [-help] [<DIRECTORY>]\n" )

    print( "-m  or  -more   Enable page flipping." )
    print( "-h  or  -help   Show this help." )
    print( "<DIRECTORY>     Name of the directory." )
    print( "                (Default is current directory)" )
end

function listDir( path, prefix )
    if path == "" then path = "\\" end  -- Path of execution.

    -- Iterate through every element (file or dir) in the path.
    for k, v in pairs( fs.list( path ) ) do
        ---[[ PAGE-FLIP
        if pageFlip then
            lineCounter = lineCounter + 1
            if lineCounter >= 17 then
                write("Press any key to continue")
                read()
                term.setCursorPos( 1, 1 )
                term.clear()
                lineCounter = 0
            end
        end
        --]]
        -- Print file/dir name.
        print( prefix.."-- "..v )
        -- Traverse next directory, if any.
        local nextDir = path.."\\"..v
        if fs.isDir( nextDir ) then listDir( nextDir, prefix.."   |" ) end
    end
end

if askingForHelp then
    printUsage()
else
    print( "Listing Directory: "..currentPath )
    listDir( currentPath, "|" )
end