What I want to do is create a file that is pretty simple. But then I wanted to put it inside the C: drive but I am not really sure how...
this is what i currently have:
file = io.open("testFile.lua", "C:")
file:write("a semi-automated message")
file:close()
It is possible to create a file in the C: drive, however, in order for the file to show up, you have to run the Lua file as an administrator via Command Prompt (or some other terminal)
file = io.open("C:\\main.txt", "a") -- appends a file named main.txt
file:write("Hello world!") -- write a bunch of stuff
io.close(file) -- close the file
Related
I decided to spring-clean and update my nvim config files/plugins, and thought I’d make proper use of the after/plug folder.
While setting up LSP (with mason, mason-lspconfig, and lspconfig), I wanted to move all the lsp language server settings out from after/plugin/lsp/init.lua to their own files (now in after/plugin/lsp/settings).
The problem is I don’t seem to be able to require them into the init.lua file.
Things I’ve tried to no avail:
require(‘after/plugin/lsp/settings/sumneko_lua.lua’)
require(vim.fn.stdpath("config") .. "/after/plugin/lsp/settings/sumneko_lua”)
require(vim.fn.expand('%:h').. ‘/settings/sumneko_lua’)
The attempt using expand works when I resource the file in nvim; but causes an error when starting nvim.
I understand that all the files in after/plugin are automagically sourced at startup. So if I had a file shared.lua:
local M = {}
function M.greet()
vim.notify("Hello!”)
end
return M
in the same folder as after/plugin/lsp/init.lua, how can I get access to the greet() function from init.lua?
Any pointers would be greatly appreciated.
It turned out to be quite a simple solution in the end: I simply updated the paths to be searched in init.lua
-- nvim/init.lua
-- Allow require to look in after/plugin folder
local home_dir = os.getenv("HOME”)
package.path = home_dir .. "/.config/nvim/after/plugin/?.lua;" .. package.path
And then I can require any file inside the after/plugin folder
e.g - require(‘lsp/settings/sumneko’) or require(‘lsp/shared’).greet()
I'm using Lua in Scite on Windows, but hopefully this is a general Lua question.
Let's say I want to write a temporary string content to a temporary file in Lua - which I want to be eventually read by another program, - and I tried using io.tmpfile():
mytmpfile = assert( io.tmpfile() )
mytmpfile:write( MYTMPTEXT )
mytmpfile:seek("set", 0) -- back to start
print("mytmpfile" .. mytmpfile .. "<<<")
mytmpfile:close()
I like io.tmpfile() because it is noted in https://www.lua.org/pil/21.3.html :
The tmpfile function returns a handle for a temporary file, open in read/write mode. That file is automatically removed (deleted) when your program ends.
However, when I try to print mytmpfile, I get:
C:\Users\ME/sciteLuaFunctions.lua:956: attempt to concatenate a FILE* value (global 'mytmpfile')
>Lua: error occurred while processing command
I got the explanation for that here Re: path for io.tmpfile() ?:
how do I get the path used to generate the temp file created by io.tmpfile()
You can't. The whole point of tmpfile is to give you a file handle without
giving you the file name to avoid race conditions.
And indeed, on some OSes, the file has no name.
So, it will not be possible for me to use the filename of the tmpfile in a command line that should be ran by the OS, as in:
f = io.popen("python myprog.py " .. mytmpfile)
So my questions are:
Would it be somehow possible to specify this tmpfile file handle as the input argument for the externally ran program/script, say in io.popen - instead of using the (non-existing) tmpfile filename?
If above is not possible, what is the next best option (in terms of not having to maintain it, i.e. not having to remember to delete the file) for opening a temporary file in Lua?
You can get a temp filename with os.tmpname.
local n = os.tmpname()
local f = io.open(n, 'w+b')
f:write(....)
f:close()
os.remove(n)
If your purpose is sending some data to a python script, you can also use 'w' mode in popen.
--lua
local f = io.popen(prog, 'w')
f:write(....)
#python
import sys
data = sys.stdin.readline()
I am learning the Lua IO library. I'm having trouble with io.write(). In Programming Design in Lua, there is a piece of code that iterates through the file line by line and precedes each line with a serial number.
This is the file I`m working on:
test file: "iotest.txt"
This is my code
io.input("iotest.txt")
-- io.output("iotest.txt")
local count = 0
for line in io.lines() do
count=count+1
io.write(string.format("%6d ",count), line, "\n")
end
This is the result of the terminal display, but this result cannot be written to the file, whether I add IO. Output (" iotest.txt ") or not.
the results in terminal
This is the result of file, we can see there is no change
The result after code running
Just add io.flush() after your write operations to save the data to the file.
io.input("iotest.txt")
io.output("iotestout.txt")
local count = 0
for line in io.lines() do
count=count+1
io.write(string.format("%6d ",count), line, "\n")
end
io.flush()
io.close()
Refer to Lua 5.4 Reference Manual : 6.8 - Input and Output Facilities
io.flush() will save any written data to the output file which you set with io.output
See koyaanisqatsi's answer for the optional use of file handles. This becomes especially useful if you're working on multiple files at a time and gives you more control on how to interact with the file.
That said you should also have different files for input and output. You'll agree that it doesn't make sense to read and write from and to the same file alternatingly.
For writing to a file you need a file handle.
This handle comes from: io.open()
See: https://www.lua.org/manual/5.4/manual.html#6.8
A file handle has methods that acts on self.
Thats the function after the : at file handle.
So io.write() puts out on stdout and file:write() in a file.
Example function that can dump a defined function to a file...
fdump=function(func,path)
assert(type(func)=="function")
assert(type(path)=="string")
-- Get the file handle (file)
local file,err = io.open(path, "wb")
assert(file, err)
local chunk = string.dump(func,true)
file:write(chunk)
file:flush()
file:close()
return 'DONE'
end
Here are the methods, taken from io.stdin
close = function: 0x566032b0
seek = function: 0x566045f0
flush = function: 0x56603d10
setvbuf = function: 0x56604240
write = function: 0x56603e70
lines = function: 0x566040c0
read = function: 0x56603c90
This makes it able to use it directly like...
( Lua console: lua -i )
> do io.stdout:write('Input: ') local result=io.stdin:read() return result end
Input: d
d
You are trying to open the same file for reading and writing at the same time. You cannot do that.
There are two possible solutions:
Read from file X, iterate through it and write the result to another file Y.
Read the complete file X into memory, close file X, then delete file X, open the same filename for writing and write to it while iterating through the original file (in memory).
Otherwise, your approach is correct although file operations in Lua are more often done using io.open() and file handles instead of io.write() and io.read().
I am using a luvit Lua environment to run my lua code through my control panel. I am looking to write to a .txt file, but with the simple code that i am running, its not working.
The reason I wish to write to a .txt file is to log notices from my Discord Bot I am working on in the Discordia library.
I have a folder called MezzaBOT. In this file i have a write.lua file and also a log.txt file. I have this simple code in my write.lua file:
io.output('log.txt')
io.write('hello\n')
io.close()
I then run in my command promt with Luvit environment:
>luvit Desktop\mezzabot\write.lua
I don't get any errors but the log.txt file continues to stay empty. Am I missing a line in my code, or do i need to access log.txt differently?
edit: my new code is the following
file = io.open('log.txt')
file:write('hello', '\n')
file:close()
and it is not making a new line for each time with \n
edit B:
Ok, i found my problem, its creating a log.txt in my C:\Users\PC.
One other problem is when writing, its not making a new line with the \n. Can someone please help me?
Lua, by default, opens files in read mode. You need to explicitly open a file in write mode if you want to write to it (see manual)
file = io.open('log.txt', 'w')
file:write('hello', '\n')
file:close()
Should work :)
In a lua-script (for Domoticz # Raspberry) I apply the following script-segment to generate an htm-file and to put it in the designated folder.
Line02text till Line30text are variables which are dynamically filled elsewhere in the lua-script.
file = io.open("/home/pi/domoticz/scripts/lua/XXXXX.htm", "w+")
-- Opens a file named XXXXX.htm (stored under the designated sub-folder of Domoticz)
-- in append mode
-- write lines to opened file
file:write("SOF<br>")
file:write(Line02text .. "<br>")
file:write(Line03text .. "<br>")
....
file:write(Line29text .. "<br>")
file:write(Line30text .. "<br>")
file:write("EOF<br>")
file:close() -- closes the open file
All seems OK, because the htm-file appears as planned.
Next steps would be to copy the file to different folder, open in browser, etc..
But Owner of the htm-file is 'root' and Permission is 0640.
For further application Owner should be different, and Permission e.g. 777.
Trying manual change or use of chmod results in report 'Permission denied' by server.
Question:
How to set (as result of the lua-script) different Owner and other Permission for the htm-file?
Lua's target is to be as portable as possible, and ownership/permissions management is very os-specific. There's no embedded functions to handle that.
You'll need to expose some native function that will do what you need with files' permissions. Or use some already existing library for that, like maybe lua-fs: (https://github.com/clementfarabet/lua-fs-0.3)