I need to load configuration variables from .conf file in lua script, and use those variables to connect to a database. I have tried using:
require "host.conf"
loadfile("host.conf") - error with unexpected token '#'
os.execute("pathToConfFile/host.lua") - and I have created a lua host file with variables in bash shell
io.popen("host.conf") etc..
None of these solutions are valid.
Is there a way to use the existing host.conf file in lua, and avoid the unexpected token error?
Thank you for your suggestions.
local original = io .open('host.conf')
local hostconf = {} -- copy contents into Lua table
for line in original :lines() do
table .insert( hostconf, line )
end ; io .close( original )
print( hostconf[1] ) -- prints line 1
You haven't specified what format your host.conf comes in, but you'll likely want to parse it better than just throwing contents in a list. Perhaps splitting each line into head / tail, based upon a delimiter ( comma, space, whatever you have between variable & value )
Thank you to everyone who helped out. My question wasn't precise and I had more to learn before I have asked and sorry about that. This is what I used to solve the problem.
local open = io.open
local function read_file(path)
local file = open(path, "r")
if not file then return nil end
local content = file:read "*a" -- *a or *all reads the whole file
local lines = {}
for line in io.lines(path) do
--print(line);
if(line:find(var)~=nil)then
local varStart=string.len(var)+2
local varEnd=string.len(line)
var=string.sub(line,varStart,varEnd)
print(var);
end
--repeat for every line
end
file:close()
return lines;
end
local fileContent = read_file("path");
Related
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 typed up my code not expecting it to work first try, and of course it didn't. I kept tweaking it for hours on end, but I kept getting the same result until I made as simple as possible.
local file = io.open("File_Name", "r")
io.output(file)
local test = io.read('*all')
io.close(file)
print(test)
After getting (no return) from this, I've decided to take a break and let someone else answer my question.
The problem with your code is that you're trying to read from whatever is defined as your input file. You only opened a file, but you didn't tell Lua to use it as the input file, so io.read won't read from the opened file, yet.
local file = io.open(filename, "r")
local test = file:read("a")
io.close(file)
print(test)
Alternatively:
local file = io.open(filename, "r")
io.input(file)
local test = io.read("a")
io.close(file)
print(test)
or
local file = io.open(filename, "r")
local test = io.input(file):read("a")
io.close(file)
print(test)
Of course you should check wether opening the file succeeded befor using the file handle.
Depending on your Lua version the read format is either *a or a. I cannot remember if both is ok in all versions. At least that's what the manual says.
I'm trying to make a Discord bot with lua and its going well so far, but I'm having a couple problems with the IO portion of lua.
I'm trying to read a large list.txt file in lua and inserting each line into a table, but so far all of my attempts didn't work.
Any advice?
Attempt #1 spits out nil:
local open = io.open
local function read_file(path)
local file = open(path, "r") -- r read mode and b binary mode
if not file then return nil end
local content = file:read "*a" -- *a or *all reads the whole file
file:close()
return content
end
local fileContent = read_file("list.txt")
local vga_files = {}
table.insert(vga_files, fileContent)
I was not able to replicate your error running your code. Your code is valid, and is likely doing what you asked it to do.
here you tell the read_file function to return nil:
if not file then return nil end
So if the file is not found you will get nil. A good step in debugging would be to add a print in the body of this if statement and see if it is getting entered.
When you call read_file:
local fileContent = read_file("list.txt")
you pass in only a file name, this means lua will look for that where ever the code is being executed, and this location maybe different from what you expect.
I validated your code works by pointing the read at itself, and printing the result.
local open = io.open
local function read_file(path)
local file = open(path, "r") -- r read mode and b binary mode
if not file then return nil end
local content = file:read "*a" -- *a or *all reads the whole file
file:close()
return content
end
print(read_file("so_io_read_test.lua"))
Additionally to get the lines you should really used io.lines which creates an iterator that you can use in a for loop.
local vga_files = {}
for line in io.lines("list.txt") do
table.insert(vga_files, line)
end
Or alternatively you can read the file and then split the lines using gmatch.
local contents = read_file("so_io_read_test.lua")
for line in contents:gmatch("([^\n]+)") do
table.insert(vga_files, line)
end
I think the tile explains it self how do I access these files and read and write them?
this is what my code looks like
local openFile = assert(io.open(wasd_ ,"r")) -- wasd_ is the .txt file I want to open
local t = openFile:read("r") -- read the file
I'm not sure if in the 1st line of code if I shut replace "wasd_" with "wasd_.txt" or the file path (i.e replace wasd_ with something like this --> C:/users/stuff/blah/thing/wasd_)
ant help is greatly appreciated
According to the documentation:
local Filename = "wasd_.txt"
local File = io.open(Filename, "r")
local FileContent = File:read("*all")
File:close()
The file will be open according to the current directory %CD%. If your current directory is C:\test\, then the open file will be C:\test\wasd_.txt. If you want to find another file, you could specify the full path C:\users\stuff\blah\thing\wasd_.txt
you can do it all-at-once if you want; Lua allows that, but you have more control over editing when you do it line-at-a-time; in case you need to use certain edits on certain lines. It's also much safer to write to a new file, so you still have your original, to compare and try again, if need be.
line by line, keeping original, writing to new text
local path = 'C:/users/stuff/blah/thing/wasd_.txt' -- wasd_ is the .txt file I want to open
local newpath = path :sub( 1, -5 ) ..'new.txt' -- C:/users/stuff/blah/thing/wasd_new.txt
local iput = assert( io.input( path ) )
local oput = assert( io.output( newpath ) )
local linenum = 0 -- used as a counter
while true do
linenum = linenum +1
local line = iput :read()
if line == nil then break end -- break out of loop if there's nothing else to read
local newline, _ = line :gsub( 'this', 'that' ) -- do your changes here
if linenum == 1 then newline = 'HEADER: ' ..newline end -- example of specific line edit
oput :write( linenum ..' ' ..newline ..'\n' ) -- read() line strips newline char, so add it back
end
iput :close()
oput :close()
You can take out all instances of linenum if it's not needed, but I would strongly recommend that you use two separate read & write files, at least until you're comfortable it's doing exactly what you want, and has no errors.
I am trying to copy only latest file from a directory using lua file.
Latest file means : depends on modified time/created time.
How can i do this?
Referring to this question: How can I get last modified timestamp in Lua
You might be able to leverage the io.popen function to execute a shell command to get the name of the file. It seems like there's no builtin function that exposes filesystem metadata or stats. Something like this might work:
local name_handle = io.popen("ls -t1 | head -n 1")
local filename = name_handle:read()
I'm not familiar with Lua, but perhaps this helps. I imagine that once you have the name of the newest file you can use the other IO functions to do the copying.
local function get_last_file_name(directory)
local command = 'dir /a-d /o-d /tw /b "'..directory..'" 2>nul:'
-- /tw for last modified file
-- /tc for last created file
local pipe = io.popen(command)
local file_name = pipe:read()
pipe:close()
return file_name
end
local directory = [[C:\path\to\your\directory\]]
local file_name = get_last_file_name(directory)
if file_name then
print(file_name)
-- read the last file
local file = io.open(directory..file_name)
local content = file:read"*a"
file:close()
-- print content of the last file
print(content)
else
print"Directory is empty"
end