I could find out here, how can I create a new file with pure Lua code. The next snippet should do it theoretically:
file = io.open("test.txt", "w")
file:write("Hello World")
file:close()
However, I can't find the created file in the folder of the source code file. Where does it save the file - if it even creates a new one?
If not, what's the way of doing it?
It will use the processes current working directory (CWD) which is going to wherever your shell/environment was when you ran the script.
Related
my program seems to "see" only the .txt files which he creates with the fopen("file.txt","w") function. I changed the working directory and put added the file to the project, but if I create the file.txt the program can't see it. the only way is to edit the one he creates with the open function
You just have a problem concerning the current directory, it is not what you expect.
When you create "file.txt" it is created in the current directory because the path is not specified, so you can open it after because it is where the program look at by default.
{edit add}
You are under MacOS probably, if you start the program by hand from a shell like /Applications/......./prog the current directory is the current directory where you are in the shell, but if you start it through its icon etc it will depends on the installation directory
I am new to lua to trying to understand and put pieces to together and looking out for some help.
I have gone through the existing articles on lua file looping but unable to get the desired output.
Question - I have a folder with files, Folder path - "D:\Test_Files\Outbound\Client\final"
Files in the folder with extension - .txt
Trying to :
Get the count of files in the folder(in this case "final" folder).
Read every file, building a loop something similar to this:
list = {}
for i=0,(#Totalfilecount) do
local fr = io.open('D:\Test_Files\Outbound\Client\final\'..filename.,'rb')
local f = fr.read('*.txt')
Customfunction(f) -- Passing file content to customfunction to apply business logic.
end
Questions :
How to get file count from a directory?
How to read the directory to check if the files with "*.txt" exist?
How to use table list to store each file name and read through the loop?
How to read each file via loop and pass the value to function "Customfunction(f)"?
Code is expected to run on windows. Please share suggestions in pure lua without using external file system functions such as 'lfs' as we do not like to import external functions.
Any Suggestions/help will be greatly appreciated!
You can't (at least shouldn't) do this without extensions to Lua. To accomplish this, you have to download LuaFileSystem library. You can do it using LuaRocks:
$ luarocks install luafilesystem
Use library as such:
require "lfs"
function dirtree(dir)
assert(dir and dir ~= "", "Please pass directory parameter")
if string.sub(dir, -1) == "/" then
dir=string.sub(dir, 1, -2)
end
local function yieldtree(dir)
for entry in lfs.dir(dir) do
if entry ~= "." and entry ~= ".." then
entry=dir.."/"..entry
local attr=lfs.attributes(entry)
coroutine.yield(entry,attr)
if attr.mode == "directory" then
yieldtree(entry)
end
end
end
end
return coroutine.wrap(function() yieldtree(dir) end)
end
An example use of code above:
for filename, attr in dirtree("D:\Test_Files\Outbound\Client\final") do
print(attr.mode, filename)
end
You have to check does extension equal to txt. To read file extension use this snippet:
function GetFileExtension(path)
return path:match("^.+(%..+)$")
end
So, to answer your question(s), you can get amount of files in directory just by counting elements in array returned in dirtree. To answer second question, just use code from the post. Table that you want is returned by dirtree(), but you may want to extract only .txt files from it. To read a file, just check other SO answers. You've got given name (in array), so use it.
EDIT: You can parse result of dir and ls command to get directory listing, but you shouldnt. Althrough this way you wouldn't need to install any libraries, your code is going to be heavily OS-depedent.
Adding libraries to your code isn't so bad. Hacking things is worse.
(Not sure file extension extracting function is going to work. I didn't make dirtree code used in this post, it belongs to David Kastrup)
Good evening,
I am currently working on a programm that takes information from a file into a Database, for testing purposes I used to open Testfiles in the classical way via IO:
function reader (file, delimeter)
local f = io.open(file)
for line in f:lines() do
lines[count] = splitty(line, delimeter)
count = count + 1;
end
end
(this part also containes the first part of a splitter)
But in the actual environment, the database programm imediatly moves the file in another directory with a name change to, for example this:
$30$15$2016$09$26$13$27$24$444Z$.Pal.INV.csv
Now I know the directory but I can't really predict the name, so I wanted to know if there might be a way to open files without knowing their name.
(and delete them after reading them)
I had ideas to use a modified link:
local inputFile = "D:\\Directory\\(*all)"
but it failed.
Other aviable information:
The system is until now only planned on Windows PCs.
The directory will always only contain the one file that is to ready, no other files.
You can use the lfs.dir iterator from LuaFileSystem to iterate through the contents of the directory. A small example:
local lfs = require("lfs")
local path = "D:\\Directory\\" -- Your directory path goes here.
for filename in lfs.dir(path) do
print(filename) -- Work with filename, i will just print it
end
If you keep a record of the files you will be able to know which one is the new one. If it is only one file, then it will be easier, you can just check the extension with a string function. From what i remember the iterator includes .. and .. lfs documentation can be found here.
-- directory name and file name should consist of ASCII-7-bit characters only
local dir = [[C:\Temp\New Folder]]
local file = io.popen('dir /b/s/a-d "'..dir..'" 2>nul:'):read"*a":match"%C+"
if not file then
error"No files in this directory"
end
-- print the file name of first file in the directory
print(file) --> C:\Temp\New Folder\New Text Document.txt
I need help writing contents of one file to another in NSIS.
I have two files config1.config and config2.config with default settings in the same folder.I just want to clear contents of config2.config file and write all contents of config1.config to config2.config.
I am getting error in below code
File /oname=c:\DataSubmissionToolFinal.war DataSubmissionToolFinal.war
Please let me know the solution.
If you just want to copy all the contents of one file into another file in the same directory, following should work for you:
Section ""
Delete "config2.config" ; deletes the previous config2.config
Copyfiles "config1.config" "config2.config"
SectionEnd
And
What are you trying to do in this?
File /oname=c:\DataSubmissionToolFinal.war DataSubmissionToolFinal.war
And what error are you getting?
I need to read file in my program so while providing path I want to give relative paths because all files to be opened will be in some folder within current folder.
I tried this:
FILE *f=fopen("./abc/p.txt","r")
abc is folder withing current folder, but fopen returns NULL. How to do this thing?
This comes from either one of those:
. or ./abc/ is not readable or traversable
./abc/p.txt is not readable
./abc/p.txt does not exist
./abc/p.txt is a broken link
Look at errno to know what's the real problem.
this will run:
FILE *f=fopen("...\\abc\\p.txt","r");