Linux Man Pages
man7.org › linux › man-pages › man2 › open.2.html
open(2) - Linux manual page
open() creat() SVr4, 4.3BSD, POSIX.1-2001. openat() POSIX.1-2008. Linux 2.6.16, glibc 2.4.
GitHub
github.com › lattera › glibc › blob › master › io › open.c
glibc/io/open.c at master · lattera/glibc
February 5, 2022 - GNU Libc - Extremely old repo used for research purposes years ago. Please do not rely on this repo. - glibc/io/open.c at master · lattera/glibc
Author lattera
Factsheet
GNU C Library
Original author Roland McGrath
Developers GNU Project, most contributions by Ulrich Drepper
GNU C Library
Original author Roland McGrath
Developers GNU Project, most contributions by Ulrich Drepper
GNU
gnu.org › software › libc
The GNU C Library - GNU Project - Free Software Foundation
The GNU C Library can be found on the main GNU ftp server (download glibc via HTTPS, download glibc via HTTP or download glibc via FTP), and its mirrors; please use a mirror if possible.
Arch Linux Man Pages
man.archlinux.org › man › open.2.en
open(2) — Arch manual pages
The POSIX.1-2008 "synchronized ... the open() flags O_SYNC, O_DSYNC, and O_RSYNC for controlling the behavior. Regardless of whether an implementation supports this option, it must at least support the use of O_SYNC for regular files. Linux implements O_SYNC and O_DSYNC, but not O_RSYNC. Somewhat incorrectly, glibc defines O_RSYNC ...
Code Browser
codebrowser.dev › glibc › glibc › sysdeps › unix › sysv › linux › open.c.html
open.c source code [glibc/sysdeps/unix/sysv/linux/open.c] - Codebrowser
Source code of glibc/sysdeps/unix/sysv/linux/open.c glibc glibc-2 on KDAB Codebrowser
GNU
sourceware.org › glibc
The GNU C Library (glibc)
What is glibc? Get Started · Get Involved · Sources · Documentation · Report a bug · Security · The GNU C Library project provides the core libraries for the GNU system and GNU/Linux systems, as well as many other systems that use Linux as the kernel. These libraries provide critical APIs including ISO C11, POSIX.1-2008, BSD, OS-specific APIs and more. These APIs include such foundational facilities as open, read, write, malloc, printf, getaddrinfo, dlopen, pthread_create, crypt, login, exit and more.
GitHub
github.com › lattera › glibc › blob › master › elf › dl-open.c
glibc/elf/dl-open.c at master · lattera/glibc
GNU Libc - Extremely old repo used for research purposes years ago. Please do not rely on this repo. - glibc/elf/dl-open.c at master · lattera/glibc
Author lattera
GNU
gnu.org › software › libc › manual › html_node › Opening-and-Closing-Files.html
The GNU C Library - GNU Project - Free Software Foundation (FSF)
This glibc manual version 2.43 (latest) is available in the following formats:
Linux Man Pages
man7.org › linux › man-pages › man3 › fopen.3.html
fopen(3) - Linux manual page
The stream is positioned at the end of the file. a+ Open for reading and appending (writing at end of file). The file is created if it does not exist. Output is always appended to the end of the file. POSIX is silent on what the initial read position is when using this mode. For glibc, the initial file position for reading is at the beginning of the file, but for Android/BSD/MacOS, the initial file position for reading is at the end of the file.
12000
12000.org › my_notes › system_calls_in_linux › system_call_in_linux.htm
How system calls work in Linux - fopen()
This file is used by the glibc build system to generate the wrapper for open() and call it __libc_open.
Top answer 1 of 2
6
Under the normal circumstances that your question present (i.e. dynamic linking to a library assumed to exist on the user's system and thus not distributed with the program) the following part of the license text will save the day for any program using glibc:
A program that contains no derivative of any portion of the Library, but is designed to work with the Library by being compiled or linked with it, is called a “work that uses the Library”. Such a work, in isolation, is not a derivative work of the Library, and therefore falls outside the scope of this License.
2 of 2
2
Whatever the glibc license is, it implements, as you note, standard C lib functions. That is, it implements a standard API. Consequently, a program which uses functions from the library (without modifying the library) cannot be considered a derivative work of the library (because you could replace the library by any other implementation of the same standard API).
That being said, if you bundled the library along with your program and distributed the whole, you would still be bound by some of the terms of the license, but if you just assume the user's system has a standard C lib and dynamic link to it (as suggested by @MansGunnarsson), then you are not bound by any of these terms (whatever they may be). So the question of the license being LGPL, GPL or proprietary does not matter anymore.
LWN.net
lwn.net › Articles › 739224
openat() was available before - why they are blaming glibc? [LWN.net]
November 16, 2017 - 1. Programmer writes code, wants more protection and decides on the use of seccomp. 2. Programmer looks at what the code needs, and comes up with the 'open' syscall. However the code doesn't call the syscall directly, but the wrapper glibc provides. 3. Code is finished, programmer moves on to the next project.
Wikipedia
en.wikipedia.org › wiki › GNU_C_Library
glibc - Wikipedia
December 28, 2025 - The Yocto Project and Debian also moved back to glibc since the release of Debian Jessie. Starting in 2001 the library's development had been overseen by a committee, with Ulrich Drepper kept as the lead contributor and maintainer. The steering committee installation was surrounded by a public controversy, as it was openly ...
Open Hub
openhub.net › p › glibc
The GNU C Library Open Source Project on Open Hub
The GNU C Library, glibc, provides the standard C library interface for GNU/Linux and other Free Software operating systems.
Baeldung
baeldung.com › home › building › what is glibc?
What Is glibc? | Baeldung on Linux
March 19, 2025 - Many software applications use the library, and it’s an essential component of the GNU/Linux operating system. glibc is open-source software and is distributed under the GNU Lesser General Public License.
Linux Man Pages
linux.die.net › man › 2 › open
open(2): open/possibly create file/device - Linux man page
Currently (2.6.31), Linux only implements O_SYNC, but glibc maps O_DSYNC and O_RSYNC to the same numerical value as O_SYNC. Most Linux file systems don't actually implement the POSIX O_SYNC semantics, which require all metadata updates of a write to be on disk on returning to user space, but only the O_DSYNC semantics, which require only actual file data and metadata necessary to retrieve it to be on disk by the time the system call returns. Note that open() can open device special files, but creat() cannot create them; use mknod(2) instead.
Phoronix
phoronix.com › news › Glibc-Code-of-Conduct
Glibc Is The Latest Open-Source Project Adopting A Code of Conduct - Phoronix
December 13, 2023 - The GNU C Library "glibc" is the latest free software project to adopt a Code of Conduct (CoC) in aiming to encourage welcoming behavior and less controversy among developers and other stakeholders when engaging this key component to the Linux software ecosystem.