Lua - Modes for File Access

Lua provides I/O library to read and manipulate files. There are two models, a Simple Model which uses io module and Complete Model which use file handle returned by io module methods. We can open a file using following syntax−

file = io.open (filename [, mode])

Where−

• filename− name of file to be opened.

• mode− an optional mode specifying the access mode of the file.

This method opens the file as per provided mode and returns a file handle which then can be used to perform further operations on the file.

Access Modes

The various file modes are listed in the following table.

Example - Opening File in Write Mode

Let us now see how to open a file in write mode first.

main.lua

-- write a file content
function writeFile()
   -- Opens a file in write mode, 
   -- create file if not present
   -- overwrite content of file if present
   f = io.open("example.txt","w")
   -- write the contents
   f:write("Welcome to tutorialspoint.com", "\n")
   f:write("Simply Easy Learning", "\n")
   -- close the file handle
   f:close()
end

-- write the file 
writeFile()

print("Content written to the file successfully.")

Output

When the above code is built and executed, it produces the following result −

Content written to the file successfully.

Example - Opening File in Read Mode

Let us now see how to open a file in read mode.

main.lua

-- read a file content and returns the same
function readFile()
   -- Opens a file in read
   f = io.open("example.txt","r")
   -- read all the contents
   contents = f:read("*all")
   -- close the file handle
   f:close()
   -- return the contents
   return contents
end

-- read the file and get the contents
contents = readFile()

-- print the contents
print(contents)

Output

When the above code is built and executed, it produces the following result −

Welcome to tutorialspoint.com
Simply Easy Learning