I am learning how work with files in Lua, and I came across a problem.
I know that:
io.output() allows me to specify the file that I will write output to.
The io.write() function simply gets a number of string arguments and writes them to the current output file.
io.close() then closes the file I am reading or writing on.
I first set io.output() to "myNewFile.txt" then I did io.write("Hello World!").
io.output("myNewFile.txt")
io.write("Hello World!")
This part worked well and myNewFile.txt got Hello World written to it.
Then I wrote io.close() to close the myNewFile.txt.
After that, I wrote io.write("Hello World!"), but I got an error:
C:\\Program Files\\lua\\lua54.exe: ...OneDrive\\Documents\\learning lua\\steve's teacher\\main.lua:9: default output file is closed stack traceback: \[C\]: in function 'io.write' ...OneDrive\\Documents\\learning lua\\steve's teacher\\main.lua:9: in main chunk \[C\]: in ?
I wanted io.write("Hello World!") to write Hello World in the terminal. I know can use print() but print() function adds extra characters like \n and things like that.
So my question is, how do I write Hello World in the terminal using io.write("Hello World!") in this situation?
I tried to search this error up on Google, but there weren't any results. I also tried joining many Discord servers, but I didn't get a proper response. I am a new developer to Lua so this all is really confusing to me.
After io.close() do a io.output(io.stdout) to set it back.
The clean way
local oldout = io.output() -- without argument returns actual output
io.output("file") -- set to a filename
-- do file operations here
-- use io.flush() where it is necessary
io.close() -- close file also do a flush()
io.output(oldout) -- set back to oldout ( normally io.stdout )
-- changing io.output() back should also close() and flush() the "file"
-- But better doublecheck this when using userdata without experience
So i got a new keyboard wit hG-keys. (hotkeys) And i'm not familiar with lua...
So could anybody give me a very simple command that sets my pc to sleep? please?
if gkey == 7 and mkey == 1 then
if event == "G_PRESSED" then
end
end
gkeys
so gkey is the key that is pressed, and mkey is the set it uses. i can have up to 54 differint scripts/macro's.
I want to know what i have to put after the last 'then' so my pc goes to sleep.
thx ahead
edit 1:
got this:
if gkey == 1 and mkey == 3 then
if event == "G_PRESSED" then
execute("rundll32.exe powrprof.dll,SetSuspendState 0,1,0");
end
end
error is: [string "LuaVM"]:40: attempt to call global 'execute'(a nil value)
and with os.execute i get this error:
[string "LuaVM"]:40: attempt to index global 'os'(a nil value)
final answer: not possible with gseries keyboard. use a shortcut
Given the reference to G-keys and the G_PRESSED in your code snippet, I am assuming you have one of the Logitech G-Series keyboards. These keyboards can be programmed so that certain keys run Lua scripts using a custom Lua 5.1 interpreter. The documentation is included with Logitech's Gaming Software program.
According to the documentation, only some of the standard library functions are supported: the string, math and table are available. However, the io, os and debug libraries are not available.
So I doubt you'll be able to make your PC go to sleep.
EDIT in response to OP edit: the Lua library you have access to has the os library removed, so you're probably not going to be able to make your computer sleep directly.
There might be an indirect way to do this by writing something that listens for debugging messages, which you can generate with OutputDebugMessage. There's a Team Speak plugin that does this. But it's probably beyond your programming ability right now and far beyond the scope of a Stackoverflow post to explain.
You can use os.execute to run an executable from Lua.
If you google "Windows sleep command line" you'll get another Stackoverflow post which shows two ways of doing it. One requires that you turn hibernation off, the other requires that you download an additional utility (PsShutdown).
Assuming you've downloaded PsShutdown and put it somewhere in your PATH, then you can use the following to sleep the computer:
os.execute('psshutdown -d -t 0')
Ok, I'm wanting to know if there's a way of running scripts from an external source with Lua. Be it another file in .txt format or from pastebin, what have you, and run the code and wait for said code to finish, and then continue on with the rest of the function. I'm not quite sure at all about how it'd work, but this is basically the idea I'm going by and isn't actual code.
function runStuff()
print("checking for stuff")
run.script(derp.txt)
wait for script
if run.script == finished
continue program
elseif nil
print("looks like this script sucks.")
end
end
runStuff()
And for example what "derp.txt" contains is:
function lookFile()
if herp.txt exists then
rename herp.txt to herp.lua
else
nil
end
end
lookFile()
I'm still new to Lua so I'm coding like a moron here, but you get my picture hopefully. I'm working on a project that'll act like an installer package for repositories based from pastebin or anywhere else that'll supply raw format outputs of lua scripts and I'm going to use that idea for it to call on scripts to run externally. So when I supply a "First Time Run" version of the program, it'll call out to a lua script that'll call to another lua script and install that script, then close.
This is for minecraft, mind you. ComputerCraft made me take interest in Lua, but anyway, hopefully you got the gist of what I'm trying to figure out. Hopefully that's doable and if not, I'll just have to figure something else out.
To load and execute a Lua code fragment you can use something like this:
local http = require("socket.http")
local response, err = http.request("url to some Lua code")
if not response then error(err) end
local f, err = (loadstring or load)(response)
if not f then error(err) end
print("done with "..response)
-- make sure you read on (in)security implications of running remote code
-- f() -- call the function based on the remote code
You probably need to use sandboxing.
I need to reboot System through a Lua Script.
I need to write some string before the Reboot happens and need to write a string in a Lua
script once the Reboot is done.
Example :
print("Before Reboot System")
Reboot the System through Lua script
print("After Reboot System")
How would I accomplish this?
You can use os.execute to issue system commands. For Windows, it's shutdown -r, for Posix systems it's just reboot. Your Lua code will therefore look like this:
Be aware that part of the reboot command is stopping active programs, like your Lua script. That means that any data stored in RAM will be lost. You need to write any data you want to keep to disk, using, for instance, table serialization.
Unfortunately, without more knowledge of your environment, I can't tell you how to call the script again. You could be able to append a call to your script to the end of ~/.bashrc or similar.
Make sure that loading this data and starting at a point after you call your reboot function is the first thing that you do when you come back! You don't want to get stuck in an endless reboot loop where the first thing your computer does when it turns on is to turn itself off. Something like this should work:
local function is_rebooted()
-- Presence of file indicates reboot status
if io.open("Rebooted.txt", "r") then
os.remove("Rebooted.txt")
return true
else
return false
end
end
local function reboot_system()
local f = assert(io.open("Rebooted.txt", "w"))
f:write("Restarted! Call On_Reboot()")
-- Do something to make sure the script is called upon reboot here
-- First line of package.config is directory separator
-- Assume that '\' means it's Windows
local is_windows = string.find(_G.package.config:sub(1,1), "\\")
if is_windows then
os.execute("shutdown -r");
else
os.execute("reboot")
end
end
local function before_reboot()
print("Before Reboot System")
reboot_system()
end
local function after_reboot()
print("After Reboot System")
end
-- Execution begins here !
if not is_rebooted() then
before_reboot()
else
after_reboot()
end
(Warning - untested code. I didn't feel like rebooting. :)
There is no way to do what you are asking in Lua. You may be able to do this using os.execute depending on your system and set up but Lua's libraries only include what is possible in the standard c libraries which does not include operating system specific functionality like restart.
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For debugging purposes in a somewhat closed system, I have to output text to a file.
Does anyone know of a tool that runs on windows (console based or not) that detects changes to a file and outputs them in real-time?
I like tools that will perform more than one task, Notepad++ is a great notepad replacement and has a Document Monitor plugin (installs with standard msi) that works great. It also is portable so you can have it on a thumb drive for use anywhere.
For a command line option, PowerShell (which is really a new command line) has a great feature already mentioned.
Get-Content someFile.txt -wait
But you can also filter at the command line using a regular expression
Get-Content web.log -wait | where { $_ -match "ERROR" }
Tail for Win32
Apache Chainsaw - used this with log4net logs, may require file to be in a certain format
When using Windows PowerShell you can do the following:
Get-Content someFile.txt -wait
I use "tail -f" under cygwin.
I use BareTail for doing this on Windows. It's free and has some nice features, such as tabs for tailing multiple files and configurable highlighting.
Tail is the best answer so far.
If you don't use Windows, you probably already have tail.
If you do use Windows, you can get a whole slew of Unix command line tools from here. Unzip them and put them somewhere in your PATH.
Then just do this at the command prompt from the same folder your log file is in:
tail -n 50 -f whatever.log
This will show you the last 50 lines of the file and will update as the file updates.
You can combine grep with tail with great results - something like this:
tail -n 50 -f whatever.log | grep Error
gives you just lines with "Error" in it.
Good luck!
FileSystemWatcher works a treat, although you do have to be a little careful about duplicate events firing - 1st link from Google - but bearing that in mind can produce great results.
Late answer, though might be helpful for someone -- LOGEXPERT seems to be interesting tail utility for windows.
Try SMSTrace from Microsoft (now called CMTrace, and directly available in the Start Menu on some versions of Windows)
Its a brilliant GUI tool that monitors updates to any text file in real time, even if its locked for writing by another file.
Don't be fooled by the description, its capable of monitoring any file, including .txt, .log or .csv.
Its ability to monitor locked files is extremely useful, and is one of the reasons why this utility shines.
One of the nicest features is line coloring. If it sees the word "ERROR", the line becomes red. If it sees the word "WARN", the line becomes yellow. This makes the logs a lot easier to follow.
I have used FileSystemWatcher for monitoring of text files for a component I recently built. There may be better options (I never found anything in my limited research) but that seemed to do the trick nicely :)
Crap, my bad, you're actually after a tool to do it all for you..
Well if you get unlucky and want to roll your own ;)
Yor can use the FileSystemWatcher in System.Diagnostics.
From MSDN:
public class Watcher
{
public static void Main()
{
Run();
}
[PermissionSet(SecurityAction.Demand, Name="FullTrust")]
public static void Run()
{
string[] args = System.Environment.GetCommandLineArgs();
// If a directory is not specified, exit program.
if(args.Length != 2)
{
// Display the proper way to call the program.
Console.WriteLine("Usage: Watcher.exe (directory)");
return;
}
// Create a new FileSystemWatcher and set its properties.
FileSystemWatcher watcher = new FileSystemWatcher();
watcher.Path = args[1];
/* Watch for changes in LastAccess and LastWrite times, and
the renaming of files or directories. */
watcher.NotifyFilter = NotifyFilters.LastAccess | NotifyFilters.LastWrite
| NotifyFilters.FileName | NotifyFilters.DirectoryName;
// Only watch text files.
watcher.Filter = "*.txt";
// Add event handlers.
watcher.Changed += new FileSystemEventHandler(OnChanged);
watcher.Created += new FileSystemEventHandler(OnChanged);
watcher.Deleted += new FileSystemEventHandler(OnChanged);
watcher.Renamed += new RenamedEventHandler(OnRenamed);
// Begin watching.
watcher.EnableRaisingEvents = true;
// Wait for the user to quit the program.
Console.WriteLine("Press \'q\' to quit the sample.");
while(Console.Read()!='q');
}
// Define the event handlers.
private static void OnChanged(object source, FileSystemEventArgs e)
{
// Specify what is done when a file is changed, created, or deleted.
Console.WriteLine("File: " + e.FullPath + " " + e.ChangeType);
}
private static void OnRenamed(object source, RenamedEventArgs e)
{
// Specify what is done when a file is renamed.
Console.WriteLine("File: {0} renamed to {1}", e.OldFullPath, e.FullPath);
}
}
You can also follow this link Watching Folder Activity in VB.NET
Snake Tail. It is a good option.
http://snakenest.com/snaketail/
Just a shameless plug to tail onto the answer, but I have a free web based app called Hacksaw used for viewing log4net files. I've put in an auto refresh options so you can give yourself near real time updates without having to refresh the browser all the time.
Yeah I've used both Tail for Win32 and tail on Cygwin. I've found both to be excellent, although I prefer Cygwin slightly as I'm able to tail files over the internet efficiently without crashes (Tail for Win32 has crashed on me in some instances).
So basically, I would use tail on Cygwin and redirect the output to a file on my local machine. I would then have this file open in Vim and reload (:e) it when required.
+1 for BareTail. I actually use BareTailPro, which provides real-time filtering on the tail with basic search strings or search strings using regex.
To make the list complete here's a link to the GNU WIN32 ports of many useful tools (amongst them is tail).
GNUWin32 CoreUtils
Surprised no one has mentioned Trace32 (or Trace64). These are great (free) Microsoft utilities that give a nice GUI and highlight any errors, etc. It also has filtering and sounds like exactly what you need.
Here's a utility I wrote to do just that:
It uses a FileSystemWatcher to look for changes in log files within local folders or network shares (don't have to be mounted, just provide the UNC path) and appends the new content to the console.
on github: https://github.com/danbyrne84/multitail
http://www.danielbyrne.net/projects/multitail
Hope this helps
#echo off
set LoggingFile=C:\foo.txt
set lineNr=0
:while1
for /f "usebackq delims=" %%i in (`more +%lineNr% %LoggingFile%`) DO (
echo %%i
set /a lineNr+=1
REM Have an appropriate stop condition here by checking i
)
goto :while1
A command prompt way of doing it.
FileMon is a free stand alone tool that can detect all kinds of file access. You can filter out any unwanted. It does not show you the data that has actually changed though.
I second "tail -f" in cygwin. I assume that Tail for Win32 will accomplish the same thing.
Tail for Win32
I did a tiny viewer by my own:
https://github.com/enexusde/Delphi/wiki/TinyLog