What is INI?

INI (Initialization) is a simple configuration file format that uses plain text to store settings in a structured way. Originally popularized by Windows, INI files organize settings into sections with key-value pairs, making them easy to read and edit by humans.

INI Syntax

INI files have a simple structure: sections enclosed in square brackets, followed by key-value pairs. Comments typically start with a semicolon (;) or hash (#).

Basic INI Example

; This is a comment
# This is also a comment

[database]
host = localhost
port = 5432
name = myapp
user = admin

[server]
host = 0.0.0.0
port = 3000
debug = false

[logging]
level = info
format = json

Syntax Rules

Sections

Sections group related settings together. Section names are enclosed in square brackets and are case-insensitive in many implementations.

[SectionName]
key1 = value1
key2 = value2

[AnotherSection]
key3 = value3

Key-Value Pairs

Each setting is a key-value pair separated by an equals sign (=) or colon (:). Whitespace around the separator is usually ignored.

[settings]
; These are equivalent
name = John Doe
name=John Doe
name : John Doe

Values

Values can be strings, numbers, or booleans. Quotes around strings are optional but recommended for values with special characters.

[types]
; String values
name = John Doe
path = "C:\Program Files\App"

; Numeric values
port = 8080
timeout = 30.5

; Boolean values
enabled = true
debug = false
active = yes
disabled = no

Comments

; Semicolon comment (traditional)
# Hash comment (also common)

[database]
host = localhost  ; Inline comment (some parsers support this)

Real-World Examples

php.ini (PHP Configuration)

[PHP]
engine = On
short_open_tag = Off
precision = 14
output_buffering = 4096

[Date]
date.timezone = UTC

[mail function]
SMTP = localhost
smtp_port = 25

[Session]
session.save_handler = files
session.gc_maxlifetime = 1440

my.cnf / my.ini (MySQL Configuration)

[mysqld]
port = 3306
socket = /var/run/mysqld/mysqld.sock
datadir = /var/lib/mysql
max_connections = 150
innodb_buffer_pool_size = 256M

[client]
port = 3306
socket = /var/run/mysqld/mysqld.sock

Git Configuration (.gitconfig)

[user]
name = John Doe
email = john@example.com

[core]
editor = vim
autocrlf = input

[alias]
co = checkout
br = branch
st = status

Desktop Entry (.desktop files on Linux)

[Desktop Entry]
Name = My Application
Comment = A useful application
Exec = /usr/bin/myapp
Icon = myapp
Terminal = false
Type = Application
Categories = Utility;

INI vs Other Formats

Limitations of INI

• No official specification - Different parsers may behave differently
• No nested structures - Only one level of sections supported
• No native arrays - Lists require workarounds like repeated keys or comma-separated values
• All values are strings - Type conversion depends on the application
• No multi-line values - Long values can be hard to manage

When to Use INI

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