GLib Documentation

The gio utility provides a command-line interface for GIO (Gnome Input/Output) features. Unlike traditional utilities that operate only on local files, gio commands can use GIO locations (URIs), such as smb://server/resource/file.txt.

Important Usage Notes:

• URIs vs Paths: Plain filenames containing a colon (:) are interpreted as URIs with unknown protocols. To treat such a filename as a local path, prefix it with ./ or use the file: protocol.
• Mount Visibility: gio focuses on mounts relevant to the user (like removable drives). It does not show all system mounts, so its output differs from tools like fdisk.

GLib provides a set of utilities in the GLibWin32 namespace to provide a level of Unix emulation on the Windows platform. These functions help bridge the gap between Windows-specific behaviors and expected Unix-like environments for applications.

Note: If your application requires full POSIX API compliance, it is recommended to use the Cygwin project instead of relying on GLib's emulation.

GLib provides a g_spawn_…() family of functions for spawning processes, offering a more convenient interface than standard UNIX fork() and exec().

Depending on your needs, you can use:

• Synchronous variants: g_spawn_sync (blocks until the process finishes).
• Asynchronous variants: g_spawn_async and g_spawn_async_with_pipes (non-blocking).
• Shell-like command line variants: g_spawn_command_line_sync and g_spawn_command_line_async (accepts a single string command line instead of an argument array).

For a higher-level API that includes stream interfaces for communicating with child processes, use GSubprocess in GIO.

glib-mkenums is a utility that parses C code to extract enum definitions and produces descriptions based on user-specified text templates. It is primarily used to generate enumeration types for the GType system, GObject properties, signal marshalling, or GSettings schemas.

Basic Usage:

glib-mkenums [OPTION...] [FILE...]

Key Features:

• Parses valid C code files.
• Substitutes keywords in templates to produce customized output.
• Supports both standard enum and bit-shift flags definitions.
• Can output to stdout or a specific file using --output <FILE>.
• Supports reading arguments from a file using @RSPFILE (useful for Windows systems with command-line length limits).

GLib provides a comprehensive suite of APIs for handling Unicode characters and strings. It is designed to work primarily with UTF-8, but also supports conversions to and from UTF-16 and UCS-4.

Key capabilities include:

• Character Classification: UTF-8 analogues to traditional ctype.h functions.
• Case Conversion: Functions for case conversion on UTF-8 strings.
• String Utilities: UTF-8 versions of standard string utility functions.
• Normalization and Collation: APIs to perform Unicode normalization and collation.
• Encoding Conversion: Functions to convert between UTF-8, UTF-16, and UCS-4 encodings.

glib-genmarshal is a utility that generates C code marshallers for callback functions used in the GClosure mechanism of GObject. Marshallers are responsible for calling the actual C callback function with the correct parameters on the stack and collecting the return value.

Marshaller List Format

The utility reads a list of marshaller specifications from files or standard input (-). Each line represents a marshaller and follows the format:

RTYPE:PTYPE,PTYPE,...

• RTYPE is the callback's return type.
• PTYPE instances are the parameter types.
• Note: The first and last arguments of the callback are always assumed to be pointers (typically gpointer).

The GMarkup parser is a small, efficient, and easy-to-use parser designed for a subset of XML. It is ideal for application data files and configuration files where your application is the sole writer.

Important Constraints:

• Do not use for interoperability with full-scale XML applications.
• Do not use for untrusted input.
• Encoding: Only UTF-8 is supported.
• Validation: There is no DTD or validation support.
• Error Handling: GMarkup does not guarantee an error for all invalid XML; it may accept documents that a full XML parser would reject. However, it will reject documents that are not well-formed.

The gresource command-line tool provides an interface to GResource. It allows you to inspect and extract resources that have been compiled into a dedicated resource file or embedded within an ELF file (such as a binary or a shared library).

When working with ELF files that contain multiple resource sections, use the --section option to target a specific section. You can identify available sections using the sections command.

GLib provides a set of fixed-width integer types to ensure consistent bit-widths across different platforms.

Best Practice: In new code, you should prefer standard C99 types (like int8_t, uint32_t, etc.) over GLib-specific types (like gint8, guint32), unless you need to maintain consistency with existing GLib APIs.

Available Types