Lua with Neowin: File I/O — io.open, Read Modes, Write Modes & io.lines | Episode 26

Programs need to work with files. In this episode we learn Lua's file I/O: opening files with io.open, reading with file:read and its mode options, writing and appending data, iterating lines with io.lines, and always closing file handles. We practice with a data file to read, process, and write results. Every keystroke is shown on screen with 3-second pauses so you can follow along at your own pace. Practice code: https://github.com/GoCelesteAI/learn-lua-in-neovim What You'll Learn: - io.open(path, mode) — opening files for reading, writing, or appending - "r", "w", "a" modes — read, write (overwrite), and append - file:read("*a") / file:read("*l") — read all or read line-by-line - file:write(text) — writing strings to a file - io.lines(path) — convenient line iterator - file:close() — always close your file handles Timestamps: 0:00 Intro 0:12 Preview 0:44 Creating data.txt 1:36 Opening files.lua 2:02 Reading a File (io.open, file:lines) 3:31 Running — read output 3:57 Writing a File (io.open "w", file:write) 6:16 io.lines shortcut 6:54 Running — write output 7:07 Appending to a File (io.open "a") 9:16 Running — append output 9:48 Processing data.txt (string.match) 12:30 Running — final output 12:43 Review 12:58 Recap 13:30 Endscreen Key Takeaways: 1. io.open returns a file handle and error message 2. "r" reads, "w" overwrites, "a" appends to files 3. file:read("*a") reads the entire file as one string 4. io.lines provides a clean iterator for line-by-line reading 5. Always close file handles to flush writes and free resources This is Episode 26 of the Learn Lua in Neovim series. New episodes cover error handling, metatables, OOP, and the Neovim Lua API — all coded inside Neovim. Taught by CelesteAI. Like & subscribe for more tutorials! #lua #neovim #programming #tutorial #beginners #learnlua #luaprogramming #neovimtutorial #luafileio #luaioopen #coding Tags lua, lua tutorial, learn lua, lua file io, lua io.open, lua file read, lua file write, lua io.lines, lua file handling, lua append mode, lua read file, lua write file, lua for beginners, neovim lua, neovim tutorial, learn lua in neovim, lua episode 26, programming tutorial, coding tutorial, beginner programming, lua 2026, neovim 2026, screenkey, code along, lua intermediate, lua file operations