---
name: "lopsub"
section: "7"
platform: "linux"
package: "liblopsub1"
version: "1.0.3-2"
release: "Debian 12 (Bookworm)"
platforms: ["linux"]
url: "https://new.carta.tech/lopsub"
---

# lopsub(7)

Long option parser for subcommands

## NAME

lopsub - Long option parser for subcommands

## About

**Lopsub** is an open source library written in **C** which aims to ease the task of creating, documenting and parsing the options of Unix command line utilities. It is suitable for simple commands as well as complex command line utilities with many subcommands where each subcommand has its own set of options. Options and documentation are kept together in a single file which can be translated to **C** code (to be included in the application), or to a manual page. The library supports single-character short options and GNU-style long options. The public API is well documented and stable.

To make use of the library, the programmer provides a so-called *suite file* which describes the options of the application in an intuitive syntax. At build time the suite file is translated into **C** code by the `lopsubgen` utility which also ships with the **lopsub** package. The generated code defines an instance of an opaque **C** structure and exposes a reference to this structure which can be passed to the *option parser* at run time, together with the usual argument vector. The option parser is part of the **lopsub** *library*, so applications need to link with `-llopsub`-llopsub In addition to the option parser, the library offers many more features. For example, there is a function for merging two different *parse results* to generate an effective configuration. This is useful for applications which can be configured through command line options and via a config file.

The suite file can also be processed into roff format to create a manual page. Conversion into html can easily be performed with tools like `grohtml` (part of **GNU roff**) or `man2html`man2html

**Lopsub** does not rely on the system's `getopt()` or `getopt_long()` functions of the C library and is thus portable across different flavors of Unix. It is known to work on **Linux**, **NetBSD** and **FreeBSD**.

## License

The **lopsub library** is licensed under the **LGPLv3** while the `lopsubgen` utility is licensed under the **GPLv3**. The examples and all code generated by the utilities, however, is licensed under the public domain. You are free to do anything you like with the generated code, including incorporating it into or linking it with proprietary software.

## Quick Start

Compile and run the minimal example included at the end of [lopsub-suite(5)](/lopsub-suite/5.md) ⟨./lopsub-suite.5.html⟩. Examine `lopsubex.c` and `lopsubex.suite` in the source tree and run the `lopsubex` command.

## API documentation

See ⟨./lopsub-api.html⟩. Alternatively, examine `lopsub.h` or `lopsub.h.m4`lopsub.h.m4

## Resources

• git clone URL: ⟨git://git.tuebingen.mpg.de/lopsub.git⟩

• gitweb: ⟨http://git.tuebingen.mpg.de/lopsub.git⟩

• The author's homepage: ⟨http://people.tuebingen.mpg.de/maan/⟩

• Send feedback to Andre Noll ⟨maan@tuebingen.mpg.de⟩