A file format is a particular way that information is encoded for storage in a computer file.Since a disk drive, or indeed any computer storage, can store only bits, the computer must have some way of converting information to 0s and 1s and vice-versa. There are different kinds of formats for...
In computing, configuration files, or config files configure the initial settings for some computer programs. They are used for user applications, server processes and operating system settings. The files are often written in ASCII and line-oriented, with lines terminated by a newline or carriage...
A computing platform includes some sort of hardware architecture and a software framework , where the combination allows software, particularly application software, to run...
A text file is a kind of computer file that is structured as a sequence of lines of electronic text. A text file exists within a computer file system...
s with a basic structure composed of "sections" and "properties".
Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...
operating system. The use of the "INI file" has been changed in Windows in favor of the registry
Windows registry
The Windows Registry is a hierarchical database that stores configuration settings and options on Microsoft Windows operating systems. It contains settings for low-level operating system components as well as the applications running on the platform: the kernel, device drivers, services, SAM, user...
, and deprecated in .NET in favor of XML .config files. The name "INI file" comes from the filename extension
Filename extension
A filename extension is a suffix to the name of a computer file applied to indicate the encoding of its contents or usage....
usually used, ".INI", that stands for "initialization". Sometimes a different file extension will be used instead of .ini, such as ".CFG", ".conf", or ".TXT".
Format
Properties
The basic element contained in an INI file is the property. Every property has a name and a value, delimited
Delimiter
A delimiter is a sequence of one or more characters used to specify the boundary between separate, independent regions in plain text or other data streams. An example of a delimiter is the comma character, which acts as a field delimiter in a sequence of comma-separated values.Delimiters represent...
The equality sign, equals sign, or "=" is a mathematical symbol used to indicate equality. It was invented in 1557 by Robert Recorde. The equals sign is placed between the things stated to have the same value, as in an equation...
(=). The name appears to the left of the equals sign.
name=value
Sections
Properties may be grouped into arbitrarily named sections. The section name appears on a line by itself, in square brackets
Bracket
Brackets are tall punctuation marks used in matched pairs within text, to set apart or interject other text. In the United States, "bracket" usually refers specifically to the "square" or "box" type.-List of types:...
([ and ]). All properties after the section declaration are associated with that section. There is no explicit "end of section" delimiter; sections end at the next section declaration, or the end of the file. Sections may not be nested.
[section]
The semicolon is a punctuation mark with several uses. The Italian printer Aldus Manutius the Elder established the practice of using the semicolon to separate words of opposed meaning and to indicate interdependent statements. "The first printed semicolon was the work of ... Aldus Manutius"...
s (;) at the beginning of the line indicate a comment
Comment (computer programming)
In computer programming, a comment is a programming language construct used to embed programmer-readable annotations in the source code of a computer program. Those annotations are potentially significant to programmers but typically ignorable to compilers and interpreters. Comments are usually...
. Comment lines are ignored.
comment text
Varying features
The INI file format is not well defined. Many programs
Computer program
A computer program is a sequence of instructions written to perform a specified task with a computer. A computer requires programs to function, typically executing the program's instructions in a central processor. The program has an executable form that the computer can use directly to execute...
support features beyond the basics described above. The following is a list of some common features, which may or may not be implemented
Implementation
Implementation is the realization of an application, or execution of a plan, idea, model, design, specification, standard, algorithm, or policy.-Computer Science:...
in any given program.
Blank Lines
Some rudimentary programs do not allow blank lines. Every line must therefore be a section head, a property, or a comment.
In computer science, whitespace is any single character or series of characters that represents horizontal or vertical space in typography. When rendered, a whitespace character does not correspond to a visual mark, but typically does occupy an area on a page...
varies. Most implementations ignore leading and trailing whitespace around the outside of the property name. Some even ignore whitespace within values (for example, making "host name" and "hostname" equivalent). Some implementations also ignore leading and trailing whitespace around the property value; others consider all character
Character (computing)
In computer and machine-based telecommunications terminology, a character is a unit of information that roughly corresponds to a grapheme, grapheme-like unit, or symbol, such as in an alphabet or syllabary in the written form of a natural language....
s following the equals sign (including whitespace) to be part of the value.
Quoted values
Some implementations allow values to be quoted, typically using double quotes
Quotation mark
Quotation marks or inverted commas are punctuation marks at the beginning and end of a quotation, direct speech, literal title or name. Quotation marks can also be used to indicate a different meaning of a word or phrase than the one typically associated with it and are often used to express irony...
The apostrophe is a punctuation mark, and sometimes a diacritic mark, in languages that use the Latin alphabet or certain other alphabets...
s. This allows for explicit declaration of whitespace, and/or for quoting of special characters (equals, semicolon, etc.). The standard Windows function GetPrivateProfileString supports this, and will remove quotation marks that surround the values.
Number sign is a name for the symbol #, which is used for a variety of purposes including, in some countries, the designation of a number...
(#) as an alternative to the semicolon for indicating comments.
In some implementations, a comment may begin anywhere on a line, including on the same line after properties or section declarations. In others, including MS Windows' GetPrivateProfileString function, comments must occur on lines by themselves.
Duplicate names
Most implementations only support having one property with a given name in a section. The second occurrence of a property name may cause an abort
Abort (computing)
In a computer or data transmission system, to abort means to terminate, usually in a controlled manner, a processing activity because it is impossible or undesirable for the activity to proceed. Such an action may be accompanied by diagnostic information on the aborted process.In addition to being...
; the second occurrence may be ignored (and the value discarded); the second occurrence may override the first occurrence (discard the first value). Some programs use duplicate property names to implement multi-valued properties.
Interpretation of multiple section declarations with the same name also varies. In some implementations, duplicate sections simply merge their properties together, as if they occurred contiguously. Others may abort, or ignore some aspect of the INI file.
Order of sections and properties.
In most cases the order of properties in a section and the order of sections in a file is irrelevant, but implementations may vary.
Name/value delimiter
Some implementations allow a colon (:) as the name/value delimiter (instead of the equals sign).
Hierarchy
Most commonly, INI files have no hierarchy of sections within sections. Some files appear to have a hierarchical naming convention, however. For section A, subsection B, sub-subsection C, property P and value V, they may accept entries such as [A.B.C] and P=V (Windows' xstart.ini), [A\B\C] and P=V (the IBM Windows driver file devlist.ini), or [A] and B,C,P = V (Microsoft Visual Studio file AEMANAGR.INI).
It is unclear whether these are simply naming conventions that an application happens to use in order to give the appearance of a hierarchy, or whether the file is being read by a module that actually presents this hierarchy to the application programmer.
Global properties (implicit global section)
Optional "global" properties may also be allowed, that are declared before any section is declared.
Escape characters
Some implementations also offer varying support for an escape character
Escape character
In computing and telecommunication, an escape character is a character which invokes an alternative interpretation on subsequent characters in a character sequence. An escape character is a particular case of metacharacters...
The backslash is a typographical mark used mainly in computing. It was first introduced to computers in 1960 by Bob Bemer. Sometimes called a reverse solidus or a slosh, it is the mirror image of the common slash....
(\). Some support "line continuation", where a backslash followed immediately by EOL (end-of-line) causes the line break to be ignored, and the "logical line" to be continued on the next actual line from the INI file. Implementation of various "special characters" with sequences escapes is also seen.
Common escape sequences
Sequence
Meaning
\\
\ (a single backslash, escaping the escape character)
The null character , abbreviated NUL, is a control character with the value zero.It is present in many character sets, including ISO/IEC 646 , the C0 control code, the Universal Character Set , and EBCDIC...
A bell code is a device control code originally sent to ring a small electromechanical bell on tickers and other teleprinters and teletypewriters to alert operators at the other end of the line, often of an incoming message...
Backspace is the keyboard key that originally pushed the typewriter carriage one position backwards, and in modern computer displays moves the cursor one position backwards, deletes the preceding character, and shifts back the text after it by one position....
A bell code is a device control code originally sent to ring a small electromechanical bell on tickers and other teleprinters and teletypewriters to alert operators at the other end of the line, often of an incoming message...
Tab key on a keyboard is used to advance the cursor to the next tab stop.- Origin :The word tab derives from the word tabulate, which means "to arrange data in a tabular, or table, form"...
Carriage return, often shortened to return, refers to a control character or mechanism used to start a new line of text.Originally, the term "carriage return" referred to a mechanism or lever on a typewriter...
In computing, a newline, also known as a line break or end-of-line marker, is a special character or sequence of characters signifying the end of a line of text. The name comes from the fact that the next character after the newline will appear on a new line—that is, on the next line below the...
Unicode is a computing industry standard for the consistent encoding, representation and handling of text expressed in most of the world's writing systems...
In mathematics and computer science, hexadecimal is a positional numeral system with a radix, or base, of 16. It uses sixteen distinct symbols, most often the symbols 0–9 to represent values zero to nine, and A, B, C, D, E, F to represent values ten to fifteen...
codepoint corresponding to ????
Example
Following is an example INI file for an imaginary program. It has two sections, one for the owner of the software, and one for a payroll database connection. Comments note who modified the file last, and why an IP address
IP address
An Internet Protocol address is a numerical label assigned to each device participating in a computer network that uses the Internet Protocol for communication. An IP address serves two principal functions: host or network interface identification and location addressing...
The Domain Name System is a hierarchical distributed naming system for computers, services, or any resource connected to the Internet or a private network. It associates various information with domain names assigned to each of the participating entities...
.
last modified 1 April 2001 by John Doe
[owner]
name=John Doe
organization=Acme Widgets Inc.
[database]
use IP address in case network name resolution is not working
server=192.0.2.62
port=143
file = "payroll.dat"
Accessing INI files
Under Windows, the Profile API is the programming interface used to read and write settings from classic Windows .ini files. For example, the GetPrivateProfileString function retrieves a string from the specified section in an initialization file.
C is a general-purpose computer programming language developed between 1969 and 1973 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system....
program demonstrates reading property values from the above sample INI file (Let the name of configuration file be dbsettings.ini)
Initialization File Mapping creates a mapping between an INI file and the Registry
Windows registry
The Windows Registry is a hierarchical database that stores configuration settings and options on Microsoft Windows operating systems. It contains settings for low-level operating system components as well as the applications running on the platform: the kernel, device drivers, services, SAM, user...
. It was introduced with Windows NT and Windows 95 as a way to migrate from storing settings in classic .ini files to the new Windows Registry
Windows registry
The Windows Registry is a hierarchical database that stores configuration settings and options on Microsoft Windows operating systems. It contains settings for low-level operating system components as well as the applications running on the platform: the kernel, device drivers, services, SAM, user...
. File mapping traps the Profile API calls and, using settings from the IniFileMapping Registry section, directs reads and writes to appropriate places in the Registry.
Using the Example above, a string call could be made to fetch the name key from the owner section from a settings file called, say, dbsettings.ini. The returned value should be the string "John Doe":
INI mapping takes this Profile API call, ignores any path in the given filename and checks to see if there is a Registry key matching the filename under:
If this exists, it looks for an entry name matching the requested section. If an entry is found, INI mapping uses its value as a pointer to another part of the Registry. It then looks up the requested INI setting in that part of the Registry.
If no matching entry name is found and there is an entry under the (Default) entry name, INI mapping uses that instead. Thus each section name does not need its own entry.
where the "name" Registry entry name is found to match the requested INI key. The value of "John Doe" is then returned to the Profile call. In this case, the @ prefix on the default prevents any reads from going to the dbsettings.ini file on disk. The result is that any settings not found in the Registry are not looked for in the INI file.
The "database" Registry entry does not have the @ prefix on the value; thus, for the [database] section only, settings in the Registry are taken first followed by settings in the dbsettings.ini file on disk.
Windows 95 is a consumer-oriented graphical user interface-based operating system. It was released on August 24, 1995 by Microsoft, and was a significant progression from the company's previous Windows products...
, Microsoft began strongly promoting the use of Windows registry over the INI file.
Extensible Markup Language is a set of rules for encoding documents in machine-readable form. It is defined in the XML 1.0 Specification produced by the W3C, and several other related specifications, all gratis open standards....
-based configuration files have become a popular choice for encoding configuration in text files. XML allows arbitrarily complex levels and nesting, and has standard mechanisms for encoding binary data
Binary file
A binary file is a computer file which may contain any type of data, encoded in binary form for computer storage and processing purposes; for example, computer document files containing formatted text...
. INI files are typically limited to two levels (sections and properties) and do not handle binary data well. Additionally, data serialization formats, such as JSON
JSON
JSON , or JavaScript Object Notation, is a lightweight text-based open standard designed for human-readable data interchange. It is derived from the JavaScript scripting language for representing simple data structures and associative arrays, called objects...
YAML is a human-readable data serialization format that takes concepts from programming languages such as C, Perl, and Python, and ideas from XML and the data format of electronic mail . YAML was first proposed by Clark Evans in 2001, who designed it together with Ingy döt Net and Oren Ben-Kiki...
can serve as configuration formats. These three alternative formats can nest arbitrarily, but have a more heavyweight syntax than the INI file.
